.' -' " Jim Pi.Qr.ce From: Bruce Ehly [BEHLY@dotstate.tx.us) Sent: Thursday. October 07. 2004 8:49 AM To: Jim Pierce Subject: Re:AWOS Yes, I can advise you as to the status of the AlvOS.
If you want the status, that is another matter; however, I will provide the info to you at no cost. We are advertising for a new contract for installation of a group of AWOSs in January
and you will be included in that group. Unfortunately, the entire process will take approximately 18 mo. from advertisement to installation. So the bottom line is that installation will
not be complete until the Fall of 􀁏􀁾􀀮􀀠 »> "Jim Pierce" <jpierce@ci.addison.tx. us> 10/5/2004 4: 50: 35 PM »> Bruce: Can you advise the status of our AWOS? The FAA guys want t know
for surer as they can use it as a secondary altimeter reference point. I f we are not going to get it they will have to buy some other equipment. Thanks, Jim Pierce, P.E. Assistant Public
Works Director P.O. Box 9010 Addison, TX 75001-9010 972-450-2879 This e-mail and any files or attachments transmitted with it contains Information that is confidential and privileged.
This document may contain Protected Health Information (PHI) or other information that is intended only for the use of the individual Is) and entity(ies) to whom it is addressed. If
you are the intended recipient, further disclosures are prohibited without proper authorization. If you are not the intended recipient, any disclosure, copying, printing, or use of this
information is strictly prohibited and possibly a violation of federal or state law and regulations. If you have received this information in error, please delete it and notify Hamid
Khaleghipour at 972-450-2868 immediately. Thank you. 1 
, , , 
i \ .. ... .. .... ·1 .... L . .l Jr I: II!·rl· l.iiiIIii. . it!. lil 
JUl-18-2001 11:36 TXDOT AVIATION DIVISION 512 416 4510 P.a2/02 DESIGNATION OF SPONSOR'S AUTHORIZED REPRESENTATIVE I, kc>Y\ W h l-t-e hu.A . c1'1 frtttOAfl er . (Name) I , ' (Title) J
p' A RJ 'l\ with the Tow", of 􀀴􀁾􀁉􀁾􀁭􀀠designateslw\I€M6i sst. j)b It.. LJks. Vlf. 􀀨􀁓􀁾􀀡􀁲Name) arne. Title) as the dl So Y\ authorized representative for the, project description,
who shall (Sponsor Name) have the authority, to make!approvals and disapprovals as required on behalf of the '"'"R:> \411\ D:p.. Ad􀁾I S dYl • (Sponsor Name) • Texas (Sponsor)ProJed-DesC-r
I 􀁆􀁾, 􀁁􀁉􀁁􀀮􀀫􀁯􀁾􀀫􀁥􀁊􀀠IJl.D..rkJl"" -;J<--LJL££O(Signature)C> bse rv'4.i-tvvI 􀁾'5 ft YI'\ (/tWOS) Date: Oe:rZ3 -(; \ DESIGNATED REPRESENTATIVE 􀁍􀁡􀁩􀁬􀁩􀁮􀁾􀁊􀁤􀁲􀁥􀁓􀀵􀀺􀀠􀁾􀀮􀁄􀀮􀀺􀁊􀀾􀁃�
�􀁽􀁃􀀠2E I 0 6 I SCM , 1'3 1-9C!:lIQ { , PhysieaVOvemight Address: ,{p fcil Wtsfj ro Ve. J4d J l SQYl I IX 75t:x:>1 I Telephone Number: q7l-tfSo -􀁾q7'1 Fax Number: 972.-􀁴􀁦􀁾􀀠-􀁾􀀿􀀳􀀷􀀠E-Mail
Address:--di2L free f> c.L. tlrJd 􀁴􀁾􀁾• TOTAl P.a2 
JUL-18-2001 11:35 TXDOT AVIRTION 􀁖􀁉􀁖􀁉􀁾􀁉􀁖􀁎􀀠,. FAX TRANSMISSION TXDOT· A...""" 125 l!. 11111 IV"" AIIIWI, T-.7t70H483 ('12)416-4$12 􀀱􀁾􀀱􀁉􀀧􀀷􀀢􀀧􀀧􀀧􀀱􀀠Fu:: (S121416-45\O.
DATI!: NUMBER OF PAGES: :2..·7/'rJVI TO: JIm fjerce.. FROM: Allison Martin Grant Manager COMMENTS: 
Actions required by fUroort sponsor for an AwOS: . __Return resolution and certification of project funds, designated representative form by Wednesday July, 18, 2001 . -.. _,--Provide
local funding of costs by September 28,2001 ($21,250 estimated) Selection options for the AWOS -immediately following receipt of bids Have electrical power line (30-amp minimum, 120voltl
and telephone line installed to the approved AWOS site (60 days following NTP on contract)-ifyou have any questions regarding this aspect ofthe..project, please contact Mr. Jim Curl
at 512-416-4532. Attend pre-construction conference in Austin -date to be determined following FAA approval of siting Ifall funds are not available by the end ofSeptember. follow this
thneline: __Provide local funding for siting by September 15, 2001 ($500.00) ..,.,-_Provide local funding for remaining of costs by November 1,2001 . ($20,750 estimated) 
SAMPLE RESOLUTION for AWOS WHEREAS, the NAME OF SPONSOR desires to install an automated weather observing system at the (name of airport); and WHEREAS, the NAME OF SPONSOR hereby offers
25% of project costs to match 75% federal funds, currently estimated to be $21,250 in local funds; and WHEREAS, local funds will be available to meet project expenditure§; and WHEREAS,
the NAME OF SPONSOR agrees to operate and maintain the installed automated weather observation system for the useful life of the asset; and WHEREAS, the NAME OF SPONSOR hereby requests
financial assistance from the Texas Qepartment of Transportation for installation of the automated weather observing system;and WHEREAS, the NAME OF SPONSOR intends to name the Texas
Department of Transportation as its agent for the purposes of applying for, receiving ap.d disbursing all funds for these improvements and for the administration of contracts necessary
for the implementation of these improvements; NOW, THEREFORE, BE IT RESOLVED, that the NAME OF .SPONSOR hereby directs NAME OR POSITION OF INDMDUAL to execute on behalf of the NAME OF
SPONSOR, at the appropriate time, and with the appropriate authorizations of this governing body, all contracts and agreements with the state of Texas, represented by the Texas Department
of Transportation, and such other parties as shall be necessary and appropriate for the implementation oithe improvements to the AIRPORT NAME. T:\D42GRANT\AI'PA\resoiution for AWOS.doc
. 
___________________________ _ 􀁾􀁾􀁾􀀢􀀠Public: Works I Engineering 16801 We,lgrove' P.O. Box 9010 Addison, Taxos 75001.9010 Telephone: 19721450·2871 • Fax: 1972] 450-2837 DATE 7-3-0/I.JOB
NO. ATTENnQN RE: A-Jd'I$(/)( !HrkltJl-'flf.t,UQ <\ , GENTLEMAN: WE ARE SENDING YOU 􀁾􀁃􀁨􀁥􀁤􀀠o Under separate cover Via ______the following Items: o Shop Drawings o Prints o Plans
0 Samples 0 Specifications 0 ___________________________ o Oopy of letter o Change order COPIES I /DATE 􀁦􀁴􀀺􀀬􀁾􀁃􀁌􀀭􀁃􀁉􀀠/:'-12-01 NO. DESCRIPTION 􀁦􀁗􀁊􀀯􀁊􀀯􀁉􀁉􀁾􀁁􀀱􀀠AI/) !flO/-CUe..
􀁪􀀡􀀮􀀧􀀩􀁾􀀵􀀮􀁦􀀮􀁨􀀬􀁬􀀶􀀮􀀬􀀮􀀬􀀠To",,? C)JN.Jii;e/f1 􀁯􀁦􀁨􀁮􀁾􀁱􀀠And, /or fi..<.. JJrbud/-anaZ /1f1 (}t In" IX boY! tJ5 OIA r A4t>n.t-' J I I FOrl"1 􀀮􀁥􀁾􀁦􀀯􀁬􀁮􀀵􀀵􀀯􀁲􀁴􀁱􀀠􀁉􀁬􀀱􀁦􀀭􀁬􀀧
􀁙􀁾􀀮􀀤􀁦􀀭􀁡􀁐􀁌􀁾􀀠(;fr-fl-f'lJn4 +U'lAd< (J, Vr' a VA ; I", 1,/'.: -, ..._--THESE ARE TRANSMITTED as checked below: o For approval 0 Approved as submitted o Resubmit ____copies for
approval 􀁾􀁆􀁯􀁲your use 0 Approved as noted o Submit copies for distribution o As requested 0 Returned for corrections o Return corrected prints o For review and comment 0 o FOR BIDS
DUE ______________ 19__ o PRINTS RETURNED AFTER LOAN TO US REMARKS ______________________________________ COPY TO _____________._______ 􀀮􀀧􀁇􀁎􀁾􀀠􀁾􀁾__ If enclosures are not as noted,
please notify us at once. 
(972) 450-700D Post Office Box: 9010 Addi$On. Texas 􀀷􀀵􀀰􀀰􀀱􀁾􀀹􀀰􀀱􀀰􀀠5300 Belt Line Rond FAX (972) 450-704.'l TO WHOM IT MAY CONCERN Please be advised that the attached document
is a true and correct copy of Resolution No. R01-036, duly passed by the Addison City Council on the 12th day of June, 2001. Duly certified by Carmen Moran, City Secretary for the Town
of Addison on the 3rd day of July, 2001. City Secretary ATTEST: SEAL 
RESOLUTION NO. R01·036 A RESOLUTION OFFERING $21,250 OF LOCAL FUNDS FOR THE PROJECT; AGREEING TO OPERATE AND MAINTAIN THE SYSTEM; REQUESTING FINANCIAL ASSISTANCE FROM TXDOT; NAMING TXDOT
AS THE AGENT FOR APPLYING FOR, RECEIVING, AND DISPERSING ALL FUNDS FOR THE AWOS SYSTEM; AND NAMING THE CITY MANAGER AS THE INDIVIDUAL TO EXECUTE ALL CONTRACTS RELATED TO THE PROJECT.
WHEREAS, the Town of Addison desires to install an automated weather observation system at the Addison Airport; and WHEREAS, the Town of Addison hereby offers 25% of project costs to
match 75% federal funds, currently estimated to be $21,250 in local funds; and WHEREAS, local funds will be available to meet project expenditures; and WHEREAS, the Town of Addison agrees
to operate and maintain the installed automated weather observation system for the useful life of the asset; and WHEREAS, the Town of Addison hereby requests financial assistance from
the Texas Department of Transportation for installation of the automated weather observation system; and WHEREAS, the Town of Addison intends to name the Texas Department of Transportation
as its agent for the purposes of applying for, receiving and disbursing all funds for these improvements and for the administration of contracts necessary for the implementation of these
improvements; NOW, THEREFORE, BE IT RESOLVED, that the Town of Addison hereby directs the City Manager to execute on behalf of the Town of Addison, at the OFFICE OF THE CITY SECRETARY
R01-036 
appropriate time, and with the appropriate authorizations of this governing body, all contracts and agreements with the State of Texas, represented by the Texas Department of Transportation,
and such other parties as shall be necessary and appropriate for the implementation of the improvements to Addison Airport. DULY PASSED BY THE CITY COUNCIL OF THE TOWN OF ADDISON, TEXAS,
this the 12th day of June 2001. Mayor ATTEST: City Sec 􀀬􀁾􀀠OFFICE OF THE CITY SECRETARY R01-Q36 
Texas Department of Transportation -Aviation Division Automated Weather Observation System Program .'"Feb ruary 2001 Date:__􀀭􀁊􀁾􀁌􀁬􀀬􀀭􀁲􀁊􀀭􀀬􀂣􀀬􀀭􀀬􀀱􀀭􀀽􀀲􀀽􀀭􀀬􀁴􀀭􀁜􀀽􀀲􀀺􀀮􀀮􀀽􀁏􀁟􀁏􀁾􀁉􀀬�
�􀀭􀁟􀀠The1Pwv1 of 4JJ ISrf/1 (Sponsor)hereby expresses their interest in acquiring an Automated Weather Observation System for the fk\.dJ5d}'\ (Airport Name). A minimum cash outlay
for the local sponsor share is currently estimated to be $21,250. The <1'bwr\ (Sponsor) estimates that these local funds will be available by: 􀁥􀁾􀁥􀁳􀁥􀁴􀁴􀁈􀀧􀁪􀀠Ava, IAh Ie. JYl
A-t rpo·r+-h-'fld (Enter date that funds are anticipated to be available.) Title , Note: This commitment for inclusion in the AWOS Program should be signed by the local authorized representative
with authority to commit to future financial obligations for the local government. Return this form by Tuesday, March 13, 2001 to: Karon Wiedemann TxDOT, Aviation Division 125 E. 1ltit
Street Austin, TX 78701 
CONSENT AGENDA #2a -Approval of the Minutes for the May 22, 2001, Council Meeting. #2b -Consideration of a Resolution authorizing the City Manager to enter into an agreement in an amount
not to exceed $111,620.30 with the FAA for installation of a remote transmitter in the Addison Airport Air Traffic Control Tower. #2c-Consideration of a Resolution authorizing the City
Manager to enter into an agreement in the estimated amount of $21,250.00 with Texas Department of Transportation for an Automated Weather Observation System (AWOS) at the Addison Airport.
fP,'O'!}P 􀁾􀀠#2d-Approval of an increase in scope in the amount of $16,212.00 for the update to the Federal Aviation Regulation Part 150 Noise Study at Addison Airport. ¥yl #2e-Approval
of a Change Order and additional funding in an amount not to exceed $20,000.00 to Freese and Nichols for an increase in 􀁾􀀱􀁾􀀠scope of work for the Sanitary Sewer Investigation. of
#2f-Approval of a Change Order in the amount of $20,105.00 and authorization of a final payment in the amount of $11,754.50 to Ed Wilson Inc. for miscellaneous pavement improvements
on Midway Road and Quorum Drive. #29 -Consideration of a Resolution authorizing the City Manager to enter into a contract in the amount of $50,000 with Atlas Enterprises for the Addison
Kaboom Town! Fireworks Show. #2h -Approval of a host site sponsorship agreement in the amount of $40,000.00 with Hand & Associates for Spikefest 2001. City Council Agenda 06-12-01 
Council Agenda Item: SUMMARY: This item is requesting that $21,250 be budgeted for the Addison Airport Automated Weather Observation System (A WOS) and that the attached resolution be
passed. FINANCIAL IMPACT: Budgeted Amount: N/A. A mid-year budget adjustment will be required. Cost: $21,250.00 Funds are available in the Airport Fund for this project. BACKGROUND:
On March 13, 2001, Council passed a resolution (ROJ-020 -attached) expressing the Town's interest in participating with TxDOT Aviation Division in the cost of an AWOS for Addison Airport.
Total project cost is estimated to be $85,000. Addison's share is estimated to be $21,250. 􀁾s10 TxDOT has advised the Town that our airport has been tentatively selected to receive
an AWOS in FY 2002. TxDOT has requested the City Council pass the attached resolution offering $21,250 of local funds for the project; agreeing to operate and maintain the system; requesting
financial assistance from TxDOT; naming TxDOT as the agent for applying for, receiving, and dispersing aU funds for the A WOS system; and naming the City Manager as the individual to
execute aU contracts related to the project. While the local share of funding is presently estimated to be $21,250 additional funds will be needed by the Town for electrical power supply,
and a telephone line to the site. These costs will not be known until the actual location of the A WOS on the Airport is known. RECOMMENDATION: Staff recommends Council pass the attached
resolution. 6/4/01 
RESOLUTION FOR AUTOMATED WEATHER OBSERVATION SYSTEM (AWOS) A resolution offering $21,250 of local funds for the project; agreeing to operate and maintain the system; requesting financial
assistance from TxDOT; naming TxDOT as the agent for applying for, receiving, and dispersing all funds for the A WOS system; and naming the City Manager as the individual to execute
all contracts related to the project. WHEREAS, the Town of Addison desires to install an automated weather observation system at the Addison Airport; and WHEREAS, the Town of Addison
hereby offers 25% ofproject costs to match 75% federal funds, currently estimated to be $21,250 in local funds; and WHEREAS, local funds will be available to meet project expenditures;
and WHEREAS, the Town ofAddison agrees to operate and maintain the installed automated weather observation system for the useful life ofthe asset; and WHEREAS, the Town ofAddison hereby
requests financial assistance from the Texas Department ofTransportation for installation of the automated weather observation system; and WHEREAS, the Town ofAddison intends to name
the Texas Department of Transportation as its agent for the purposes of applying for, receiving and disbursing all funds for these improvements and for the administration ofcontracts
necessary for the implementation ofthese improvements; NOW, THEREFORE, BE IT RESOLVED, that the Town of Addison hereby directs the City Manager to execute on behalf ofthe Town of Addison,
at the appropriate time, and with the appropriate authorizations ofthis governing body, all contracts and agreements with the State ofTexas, represented by the Texas Department of Transportation,
and such other parties as shall be necessary and appropriate for the implementation ofthe improvements to Addison Airport. 
PUBUC WORKS DEPARTMENT (972) 450-2871 MPost Office Box 9010 Addison, Texas 7S0019010 16801 Westgrove May 21,2001 Mr. David S. Fulton, Director Texas Department ofTransportation Aviation
Division 125 E. 11 th Street Austin, TX 78701-2483 Re: Addison Airport AWOS Dear Mr. Fulton: We were certainly glad to hear the good news about our tentative selection for an AWOS system
at Addison Airport. We are working on the items requested in your letter ofMay 1, 2001 to Mayor Wheeler. However, to assist us in making decisions about the options available to the
system, and budgeting, would you please send descriptive information and estimated costs regarding the precipitation sensor, thunder strike alert, uninterruptible power supply and NADIN
interface mentioned in your Jetter? Your attention to this matter will be most appreciated. Please call me at 972-450-2879 if you have any questions. Very truly yours, 􀁔􀁏􀁗􀁏􀁏􀁦􀁁􀁤􀁾􀁾􀀠ames
C. Pierce, Jr., P.E. Assistant Public Works Director cc: Chris Terry, Assistant City Manager Michael E. Murphy, P.E., Director ofPublic Works Mark Acevedo, Buildings and Fleet Manager

TOWN OF ADDIsoN To: Alii$(fY\ rnarHI1 Company: ]X bot l±vu:rHtlYl FAX#: S'IJ.-lflb-'15'10 Date: r;; :4-0 I # of pages (including cover): 3 Re: A:vJ 05 o Original in mail o Per your request
PUBLIC WORKS , . i From: Jim Pierce, P.E. Asst. Public Wks. Dir. Phone: 972/450-2879 .FAX: 972/450-2837 jpierce@ci.addison.tx.us 16801 Westgrove P.O.Box 9010 Addison, TX 75001-9010 o
FYI o Call me 
. Texas Department of Transportation -Aviation Division Automated Weather Observation System Program February 2001 Date: rY1.41"0 The Town ofAddison hereby expresses their interest in
acquiring an Automated Weather Observation System for the Addison Municipal Airport. A minimum cash outlay for the local sponsor share is currently estimated to be $21,250. The Town
ofAddison estimates that these local funds will be available by: . 􀀦􀁾􀁓􀁍􀀫􀁉􀁾􀁖􀀴􀁩􀁫􀁢􀁬􀁾􀀠(Enterdate1hat funds me .. to be available.) -+< 􀀧􀁾􀀰C:ITQ ":;:) Authorized Local Representative
Y<C5V1. LJ hI 􀀭􀁫􀁨􀁾􀀿􀁡􀀮􀁊􀀠Typed Name ofAuthorized Local Representative C Jt; rv1 4V1 o..j e r TItle Note: This commitment for inclusion in the AWOS Program should be signed by
the local authorized representative with authority to commit to future financial obligations for the local govemment. Return this form by Tuesday, March 13, 2001 to: Karon Wiedemann
TxDOT, Aviation Division 125 E. 11111. Street Austin, IX 78701 
RESOLUTION NO. R01·020 A RESOLUTION BY THE CITY COUNCIL OF THE TOWN OF ADDISON, TEXAS, AUTHORIZING THE CITY MANAGER TO EXPRESS THE TOWN'S INTEREST IN AN AUTOMATED WEATHER OBSERVATION
SYSTEM (AWOS) FOR THE ADDISON MUNICIPAL AIRPORT, WITH AN ESTI MATED LOCAL SHARE IN THE AMOUNT OF $21,250. WHEREAS, the installation of AWOS would provide any pilot exact weather information
at Addison Airport by radio; and WHEREAS, the weather information would also be available 24 hours per day through the National Weather Service; and WHEREAS, the $21,250 local share
of funding, plus the cost of providing electrical and telephone service would come from the Airport Fund; now, therefore, BE IT RESOLVED BY THE CITY COUNCIL OF THE TOWN OF ADDISON, TEXAS:
THAT, the City Council does hereby authorize the City Manager to express the Town's interest in an Automated Weather Observation System (AWOS) for the Addison Municipal Airport, OFFICE
OF THE CITY SECRETARY R01·020 
DULY PASSED BY THE CITY COUNCIL OF THE TOWN OF ADDISON, TEXAS, this the 13th day of March 2001. Mayor ATTEST: 􀁾􀁎City Secr OFFICE OF THE CITY SECRETARY R01-020 
co roy I Texas Department of Transportation AVIATION DIVISION 125 E. 11TH STREET' AUSTIN, TEXAS 78701-2483 • 5121416-4500 • FAX 5121416-4510 May 1, 2001 The Honorable R. Scott Wheeler
Mayor Town ofAddison PO Box 9010 Dallas, Texas 75001-9010 Dear Mayor Wheeler: Congratulations! The Addison Municipal Airport has been tentatively selected to receive an Automated Weather
Observing System (AWOS) for fiscal year 2002. The state fiscal year begins September 1, 2001. In order to begin our grant approval process, we must have a signed resolution passed byyour
governing body, designation ofproject representative, and a certification ofproject funds. Copies are attached and should be completed and returned by July18. 2001. Your grant will be
scheduled for Transportation Col1llllis6ion approval onAugust go, 2001. Additionally, a publicheari:ngwill be held onAugust 6, 20018t ouroffice for public comments regarding funding
for all grants to be issued at this time for thiS program. While you are . certaiulywe!comed to attend, your attendance is not necessary. These hearings typically last no more than 10
to 15 minutes. Following Commission approval ofyourgrant, an Airport Project Participation Agreement will be issued. local funds, currently estimated to be $21,250, should be available
by September 28, 200L Ifhowever, yourbudget will not suffice for this amountoffunding, we askthatyou do have available $500 for your share ofthe siting costs for the AWOS. Then the remainder
ofyour funds will be required by November 1, 200L Please call Allison Martin at 512-416-4512 ifthis funding schedule does not suffice. We anticipate bidding the AWOS contract by early
October, 2001. Therefore, it is imperative that the ahove deadiines be met. Contact Allison ifyou are unable to meet any ofthese deadiines so appropriate arrangements and changes can
be made. Following receipt ofthe bids, you will be contacted to decide which options you desire to add to your system. The basesystems will be AWOS-III with options to upgrade to precipitation
sensor, thunder strike alert, uninterruptible power supply and a NADIN interface for reporting oflocaI weather to flight service stations. Additionally, youwill be asked to attend at
least onepre-<:anstruction conference in Austin and to provide power and a telephone lineto theAWOS site. Other milestones that you will be required to meet canbefound on the attachment
to this letter. 􀁾􀀧􀁏􀀯􀀭􀁨David S. Fulton Director, Aviation Division 00: Mr. Jim Pierce,.Assistant City Engineer An Equal Opportunity Employer 
􀀢􀀮􀀠􀁮􀁾􀀰􀁙􀁬.􀀻􀀺􀀻􀀬􀀬􀀭􀁾􀀺􀀮􀀮􀀠K 􀀭􀀺􀀺􀀺􀀺􀀮􀁾.... 􀁾I Texas Department of Transportation AVIATION DIVISION 125 E. 11TH STREET' AUSTIN, TEXAS 78701-2483 • 5121416·4500 • FAX
5121416-4510 May1,2001 The Honorable R. Scott Wheeler Mayor Town ofAddison PO Box 9010 Dallas, Texas 75001-9010 Dear Mayor Wheeler: Congratulations! The Addison MunicipaIAirport has
been tentatively selected to receive an Automated Weather Observing System (AWOS) fur fisca1 year 2002. The state fiscal year begins September 1, 2001. In order to begin our grant approval
process, we must have a signed resolution pissed by your governing body, designation ofproject representative, and a certification ofproject funds. Copies are attached and should be
completed and returned by July 18, 2001. Your grant will be scheduled fur Transportation Commission approval On August 30, 2001. Additionally, II public hearing will be held on Augost
6,2001 at our office ror public comments regarding funding fur all grants to be issued at this time fur this program. While yeu are certainly welcomed to attend, your attendance is not
necessary. These hearings typiea1ly last no more than 10 to 15 minntes. Following Commission approval ofyour grant, an Airport Project Participation Agreement will be issued. l£Jca1
funds, eurrently estimated to be $21,250, should be available by September 28, 2001. Ifhowever, your budget will not suffice fur this amount offunding, we ask that you do have available
$500 fur your share of the siting costs for the AWOS. Then the remainder ofyour funds will be required by November 1, 2001. Please ea1l Allison Martin at 512-416-4512 ifthis funding
schedule does not suffice. We anticipate bidding theAWOS contract by early October, 2001. Therefure, it is imperative that the above deadlines be met. Contact Allison ifyeU are unable
to meet any ofthese deadiines so appropriate arrangements and changes can be made. Following receipt ofthe bids, you will be contacb!d to decide which options yeu desire to add to your
system. The base systems will be AWOS-III with options to upgrade to precipitation sensor, thunder strike alert, uninterruptible power supply and a NADIN interface for reporting oflocal
weather to flight service stations. Additionally, you will be asked to attend at least one pre-construction conference in Austin and to provide power and a telephone line to the AWOS
site. Other milestones that yeu will be required to meet can be round on the attachment to this letter. 􀁾􀀧􀁏􀀯􀀮􀁢David S. Fulton Director, Aviation Division ce: Mr. Jim Pierce, Assistant
City Engineer An Equal Opportunity Employer 
Actions required by §rlrport sponsor for an A WQS: . 􀁟􀁾􀁒􀁥􀁴􀁵􀁲􀁮􀀠resolution and certification of project funds, designated representative form by Wednesday July, 18, 2001 . -..
__.Provide local funding of costs by September 28, 2001 ($21,250 estimated) Selection options for the AWOS -immediately following receipt of bids Have electrical power line (30-amp minimum,
120 volt) and telephone line installed to the approved AWOS site (60 days following NTP on contract)-ifyou have any questions regarding this aspect of the. project, please contact Mr.
Jim Curl at 512-416-4532. Attend pre-construction conference in Austin -date to be determined following FAA approval of siting Ifan funds are not available by the end of September, follow
this tbnelble: . 􀁟􀁾􀁐􀁲􀁯􀁶􀁩􀁤􀁥local funding for 􀁳􀁩􀁴􀁩􀁮􀁾􀀠by September 15, 2001 ($500,00) 'I' Provide local funding for remaining of costs by November 1,2001 . ($20,750 estimated)

SAMPLE RE'SOLUI'ION for AWOS . WHEREAS, the NAME OF SPONSOR desires to install an automated weather observing system at the (name of airport); and WHEREAS, the NAME OF SPONSOR hereby
offers 25% of project costs to match 75% federal funds, currently estimated to be $21,250 in local funds; and WHEREAS, local funds will be available to meet project expenditure.!!; and
WHEREAS, the NAME OF SPONSOR agrees to operate and maintain the installed automated weather observation system for the useful life of the asset; and WHEREAS, the NAME OF SPONSOR hereby
requests financial assistance from the Texas I{epartment of Transportation for installation of the automated weather observing 􀁳􀁹􀁳􀁴􀁥􀁭􀁾and WHEREAS, the NAME OF SPONSOR intends
to name the Texas Department of Transportation as its agent for the purposes of applying for, receiving a!ld disbursing all funds for these improvements and for the administration of
contracts necessary for the implementation of these improvements; NOW, THEREFORE, BE IT RESOLVED, that the NAME OF sPoNSOR hereby directs NAME OR POSmON OF INDIVIDUAL to execute on behalf
of the NAME OF SPONSOR, at the appropriate time, and with the appropriate authorizations of this governing body, aU contracts and agreements with the State of Texas, represented by the
Texas Department of Transportation, and such other parties as shall be necessary and appropriate for the implementation of the improvements to the AIRPORT NAME. T:\D42QRAN1'\APPA\resolution
for AWOS.doc . 
CERTIFICATION OF PROJECT FUNDS 􀁾􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀁾􀀧􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀀭􀁾􀀭􀀭􀀭􀀭􀀭􀀭􀀭(Name) (Title) do certify that su£Iiclent funds to meet the
___-:-:::-__:--::-,,---,-_____ (Sponsor's Name) share of-project costs as identified in the resolution for the project and will be available in accordance with the schedule shown below:
SPONSOR FUNDS Source Amount Date Available ,Texas (Sponsor) 􀁂􀁹􀀺􀁾􀂷__________---'_ Title:____________ Date:--------------------
Texas Department ofTransportation -Aviation Division Automated Weather Observation System Program ",February2001 The (Sponsor)hereby expresses their interest in acquiring an Automated
Weather Observation System for the (Airport Name). A minimum cash outlay for the local sponsor share is currently estimated to be $21,250. The _----,____-'(Sponsor) estimates that these
local funds will be available by: (Enter date that funds are anticipated to be available.) Authorized Local Representative Typed Name ofAuthorized Local Representative Title Note: This
commitment for inclusion in the AWOS Program should be signed by, the local authorized representative with authority to coromit to future financial obligations for the local goveroment.
Return this form by Tuesday, March 13, 2001 to: Karon Wiedemann TxDOT, Aviation Division 125 E. 11th Street Austin, TX 78701 
JIM PIERCE, P.E. Assistant Public Works Director (972) 450-2879 (912) 4S()'2837 FAX jpierce@ci.addison.tx.us Town of Addison 16801 Westgrove Dr, P.O. Box 9010, Addison, Texas 75001-9010
􀁦􀀿􀁾FYI 
March 5, 2001 MEMORANDUM To: Chris Terry, Assistant City Manager Through: Mike Murphy, P.E., Director ofPublic Works From: Jim Pierce, P.E., Assistant Public Works Director Subject:
Airport Automated Weather Observation System (A WOS) We have received a letter (attached) dated February 23, 2001 from TxDOT Aviation Division regarding the installation of an A WOS
at Addison Airport. The system would provide any pilot exact weather information at Addison Airport by radio. The weather information would also be available 24 hours per day through
the National Weather Service. Staff believes an A WOS would be a good addition for Addison Airport. The estimated $21,250 local share of funding, plus the cost of providing electrical
and telephone service would come from the Airport'Fund. Staff recommends that the City Manager be authorized to express the Town's interest in the A WOS program and return the appropriate
form to TxDOTAviation Division. 
· Texas Department orTransportation -Aviation Division Automated Weather Observation System Program February 2001 . The Town ofAddison hereby expresses their interest in acquiring an
Automated Weather Observation System fur the Addison Municipal Airport. A mininmm cash outlay fur the local sponsor share is currently estimated to be $21,250. The Town ofAddison estimates
that these local funds will be available by: . 􀁦􀁲􀁥􀀮􀁓􀁍􀀺􀁈􀁾􀁬􀁤􀀡􀁴􀁡i fa bIe.-: (l!:ntetdatethattimdsare .• to beavailahl•.) 􀁾􀀭􀀽􀀠l0t:ttR ":::;2 Authorized Local Representative
f<CSY\ LJhl khl?ttd Typed Name ofAuthorized Local Representative C Ir; 􀁴􀁙􀀱􀀮􀁾􀁙􀁬􀀼􀁴􀁪􀀠e r Title Note: This commitment for inclusion in the AWOS Program should be signed by the
local authorized representative with authority to commit to future financial obligations for the local government Return this form by Tuesday, March 13, 2001 to: Karon Wiedemann TxDOT,
Aviation Divis.ion 125 E. 11til Street Austin, TX 78701 
I Texas Department of Transportation AVIATION DIVISION 125 E. 11TH STREET' AUSTIN, TEXAS 78701·2483 • 5121416·4500 • FAX 5121416-4510 Februaxy 23, 2001 Mr. Jim Pierce .Asst. City Engineer
POBox 9010 Addison, Texas 75001·9010 Re: Addison Municipal Airport Dear Mr. Pierce: Following the recent successful installation ofsixteen Automated Weather Observation Systems (AWOS)
at airports across the state, TxDOT Aviation Division is now ready to expand and continue the AWOS program. The program will utilize a statewide contract for siting, iDstalIation, and
maintenance ofgroups ofAWOS illsystems. TxDOT is now acoepting letters ofinterest from eligible airport sponsors fur inclusion in the program. The systems, corrently estimated to cost
approximately $85,000 per unit, will require a 25% local match ofapproximately $21,250. However, final costs will be based on actual bid prices. We anticipate including in the bid proposal
a three year maintenance agreement for the program, subject to availability offunds. If; due to bid prices, we are unable to include maintenance inthe bid package, the sponsor must then
assume responsibility fur oogoing maintenance costs. Currently, yearly maintenance costs can run about $3,000 per year, not including parts. Additionally, sponsors will be required to
bear the costs fur installation ofnecessary electrical power supply and telephone line installation costs. Ifyour airport would like to be included in this program, please complete and
return the enclosed form by Tuesday, March 13, 2001. Ifyou have previously applied for an AWOS, we request that you complete the enclosed form ifyou are still interested. It is anticipated
that local match would be required as early as late summer or early fall 2001, depending on necessary siting approval as requiredby FAA. For questions regarding this program, please
call Karon Wiedemann at 512-416-4520. 􀀢􀁓􀁪􀀩􀁊􀁾David S. Fulton Director cc: The Honorable R Scott Wheeler, Mayor An Eoual DDooriunitv FmnlnvAr 
HP LaserJet 3200se TOALASERJET 3200 invent 9724502837 MAR·14·2001 08:18 Fax Call Report Job Date Time Type Identification Duration Pages Result 584 3/14/2001 08:17:21 Send 915124164510
1:13 2 OK l'OWNOF ADDISON' T.: j;::q rCl'1 4J1.eJe !1Mrl Company: Tx ]JOtfhMM FAX": £l;t.-'tl("· '15"10 Dat.: 3-I <+-oj # .rpog.. (Indudlog .....):...d...... Re: Adals"" A-tJel $ PuBLIC
WORKS \" From: Jim 􀁐􀁩􀁥􀁲􀁣􀁾􀀠P.E. Asst. Public Wks. J)ir. Pb•••: 9721450·2879 FAX: 9721450·2837 jpStm@u..ddll(ld,b:.1IIt 16801 Westgro•• P.0:llo.9010 Add...., TX 75001-9010 
􀁾􀀮􀀠, Texas Department or Transportation -Aviation Division Automated Weather Observation System Program February 2001 L3, J.6v/I The Town ofAddison hereby expresses their interest
in acquiring an Automated Weather Observation System for the Addison Municipal Airport. A minimum cash outlay for the local sponsor share is currently estimated to be $21,250. The Town
ofAddison estimates that these local funds will be available by: . . 􀀦􀁾􀀤􀁍􀀫􀁬􀁾􀁖􀀴i lab Ie(Enterdate that funds are • to be avallable.) -R \v0 t1, 9q/:) Authorized Local Representative
R6Yl 􀁌􀁊􀁨􀁬􀁫􀁨􀁾􀀿􀁡􀀮􀁤􀀠Typed Name ofAuthorized Local Representative C if'] yY1 t! Y1 <tj er Title Note: This commitment for inclusion in the AWOS Program should be signed by the
local authorized representative with authority to commit to future financial obligations for the local government. Returnthis form by Tuesday, March 13, 2001 to: '. Karon Wiedemann TxDOT,
Aviation Division 12S E. 111h Street Austin, TX 78701 
Administrative Recommendation: Administration recommends approval. Item #R9-Consideration of Resolution authorizing the City Manager to express the Town's interest in an Automated Weather
Observation System (AWOS) for the Addison Municipal Airport, with an estimated local share in the amount of $21 ,250. Attachments: 1. Memo from Jim Pierce, Assistant Director of Public
Works 2. Letter from David Fulton, Director, TxDOT Aviation Division 3. Form Administrative Recommendation: Administration recommends approval. Item #R10 -Consideration of a Resolution
authorizing the City Manager to request Texas Department of Transportation Aviation to switch the FY2001 $150,000 entitlement grant from the Terminal Apron Project to an update of the
Airport Master Plan. Attachment: 1. Memo from Jim Pierce, Assistant Director of Public Works Administrative Recommendation: Administration recommends approval. Adjourn Meeting Posted
5:00 p.m. March 7, 2001 Carmen Moran City Secretary THE TOWN OF ADDISON IS ACCESSIBLE TO PERSONS WITH DISABILITIES. PLEASE CALL (972) 450·2819 AT LEAST 48 HOURS IN ADVANCE IF YOU NEED
ASSISTANCE. City Council Agenda 03·13-01 
..... 􀀭􀁾􀀮􀀺􀀺􀀺􀀺􀀺􀀮􀀠􀁾􀀠I 􀁾.. Texas Department of Transportation AVIATION DIVISION 125 E. 11TH STREET' AUSTIN, TEXAS 78701-2483 • 5121416-4500 • FAX 5121416-4510 February 23,2001
Mr. Jim Pierce Asst. City Engineer PO Box 9010 Addison, Texas 75001-9010 Re: Addison Municipal Airport Dear Mr. Pierce: Following the recent successful installation ofsixteen Antomated
Weather Observation Systems (AWOS) at airports across the state, TxDOT Aviation Division is now ready to expand and continue the AWOS program. The program will utilize a statewide contract
fur siting, iristal1ation, and maintenance ofgroups ofAWOS msystems. TxDOT is now accepting letters ofinterest from eligible airport sponsors fur inclusion in the program. The systems,
currently estimated to cost approximately $85,000 per unit, will require a 25% local match of approximately $21,250. However, final costs will be based on actnal bid prices. We anticipate
including in the bid proposal a three year maintenanc.e agreement fur the program, subject to availability offunds. If, due to bid prices, we are unable to include maintenance in the
bid package, the sponsor must then assume responsibility fur ongoing maintenance costs. Currently, yearly maintenance costs can run about $3,000 per year, not including parts. Additionally,
spensors will be required to bear the costs for installation ofnecessary electrical power supply and telephone line installation costs. Ifyour airport would like to be included in this
program, please complete and return the enclosed form by Tuesday, MarCh 13, 2001. Ifyou have previously applied for an AWOS, we request that you complete the enclosed form ifyou are
still interested. It is anticipated that local match would be required as early as late summer or early fall 2001, depending on necessary siting approval as required by FAA. For questions
regarding this program, please call Karon Wiedemann at 512-416-4520. 􀀢􀁓􀀧􀁦􀁬􀁊􀀮􀁾􀀠David S. Fulton Director co: The Honorable R Scott Wheeler, Mayor An Equal Opportunity Employer

-------------------------Texas Department of Transportation -Aviation Division Automated Weather Observation System Program February 2001 Date: The Town ofAddison hereby expresses their
interest in acquiring an Automated Weather Observation System for the Addison Municipal Airport. A minimum cash outlay for the local sponsor share is currently estimated to be $21,250.
The Town ofAddison estimates that these local funds will be available by: (Enter datethat funds are anticipated til be available.) Authorized Local Representative Typed Name ofAuthorized
Local Representative Title Note: This commitment for inclusion in the A WOS Program should be signed by the local authorized representative with authority to commit to future financial
obligations for the local government. Return this form by Tuesday, March 13, 2001 to: Karon Wiedemann TxDOT, Aviation Division 125 E. 111h Street Austin, TX 78701 I 
HP LaserJet 3200se TOALAS£RJET 3200 invent 9724502837 MAR-2-2001 16:37 Fax Call Report Job Date Time Type Identification Duration Pages Result 376 3/2/2001 16:35:51 Send 99727889334
1:22 3 OK TOWN OF ADDISoN . PuBLIC WORKS To: ',Dg.v" 􀁾􀁦􀁬􀀺􀀭􀁦􀀠From: Jim PIerce, P.E. Asst. Public Wks. Dlr. Company: \Jg $ hU1t Jm PbOM: 9721450-2879 ·FAX: 97Z1450-2837 FAX#: 'f1'J..
-7$'-1:11'1 􀁪􀁾􀁤􀁤􀁨􀁡􀁮􀀮􀁴􀀺􀁊􀀺􀀮􀁵􀁴􀀠Date: 􀀻􀀻􀁾􀀻􀀢􀀭􀁯􀁬􀀠]6801 Westgrove P.O.B..9010 # of pag.. (lAd.dlng 􀁲􀁯􀁶􀁥􀁲􀀩􀀺􀁾􀀠Addison, TX 75001.9010 Re:. ,4 [U05 f!7?Jr<! r>'I
E 
ADDIsoN PUBLIC WORKS 􀁊􀀩􀁡􀀮􀁖􀁾􀀠£ rc-{To: From: Jim Pierce, P.E. Asst. Public Wks. Dir. Company: \JQ$ h, rlf kt Phone: 972/450-2879 FAX: 972/450-2837 FAX#: ql'J-"768'-9'33''1 jpierce@ci.addisoD.tx
.us Date: :3 􀁾;2.-6/16801 Westgrove P.O.Box 9010 # of pages (including cover): 3 Addison, TX 75001-9010 Re: IttU05 &9rqrYl <.I o Original in mail o Per your .request o FYI o Call me
Comments: 􀁄􀁾􀀡􀀠9st 􀁾􀁾􀁟􀁾􀀠􀁾􀁤􀁲􀀿􀀠􀁔􀁨􀁾􀁾􀀠1/1/􀁬􀁾ftW\. ( J v 
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U.S. DEPARTMENT OF TRANSPORTATION ORDER 6560.20BFEDERAL AVIA TlON ADMINISTRATION 7/20/98 SUBJ: SITING CRITERIA FOR AUTOMATED WEATHER OBSERVING SYSTEMS (AWOS) 1. PU.RPOSE. This order
establishes· the siting criteria for AWOS's at airports and heliports. It applies to all airports and heliports. Compliance with this order is ,required to provide pilots representative
weather information. 2. DISTRIBUTION. This order is distributed to the division' level in Washington headquarters except to the branch level in the Airway Facilities Service, Air Traffic
Plans and Requirements Service, Flight Standards Service, and Office of Air Traffic Systems Development; to the section level of Airway Facilities, Air Traffic, Airports, and Flight
Standards in the regions; to the branch level in the Federal Aviation Administration (FAA) Logistics Center and the FAA Academy at the Mike Monroney Aeronautical Center; and a standard
distribution to all Airway Facilities field offices. 3. CANCELLATION. Order 6560.20A, Siting Criteria for Automated Weather Observing Systems (AWOS), dated May 14, 1990, is canceled.
4. BACKGROUND. This order is in compliance with the draft Federal Standard for Siting Meteorological Sensors at Airports. Changes to this standard approved by the Federal Coordinator
for Meteorological Services and Supporting Research will be reviewed for potential inclusion in this order. 5. DEFINITIONS. Appendix 2, Acronyms, contains acronyms used in the order.
6. APPLICATION. This order implements the siting standards contained in the draft Federal Standard for Siting 􀁍􀁾􀁴􀁥􀁯􀁲􀁯􀁬􀁯􀁧􀁩􀁣􀁡􀁬􀀠Sensors at Airports (appendix 1). Sensor siting
in accordance with this standard meets the requirements of Section 77.15(c) of the Federal Aviation Regulations (FAR) and is exempt from further Part 77 study. Any exceptions to the
standard or special situations shall require an FAA obstruction evaluation/airport Distribution: A-W (AF/RS/FS/UA) 􀀭􀁾􀁪􀁾_ ---. --Initiated By: AUA-430 )" A-X (AF/AT/ASIFS) -4; A-Y
(AY/DE) -3; A-FAF-O (S
TD) 6560.20B 1/20/98 airspace 􀁡􀁮􀁡􀁬􀁹􀁳􀀺􀁴􀀭􀀡􀁬􀀬􀀮􀀨􀀺􀀨􀀶􀁾􀀯􀁁􀁁􀁁􀀩􀀠aeronautical study in accordance with Part 77 of 􀁴􀁾􀀬􀁥􀀢􀀧􀁅􀀺􀁬􀀬􀁲􀁒􀀧􀀠t:Q"'"determine if a substantial'
adverse effect would be q:·€(i:lt'ed forJalrcraft operations.1,l,\\" ..,0, ., ./' "'\""\ .../7. EXCEPTI0,!;'{IS,,/' If systems are installed in accordance with this order, there¥ls a
high probability that, as far as location is concerned, the systems will be able to provide the usable information desired. Since desired locations are not always available due to excessive
physical or economic reasons, compromises may have to be considered and less than desired locations may have to be selected. If this occurs, it must be understood that the alternative
location must still allow the system to provide accurate information. Actual commisSioning of an installed site or sensor may be delayed until it operationally demonstrates the validity
of the information provided. If the information meets the requirements, it shall be commissioned/approved. Corrective action will be required if system/sensor information does not demonstrate
valid data. This may mean removal of the sensor, correction of whatever is adversely affecting the sensor, or relocation of the sensor or system. Since the desire is to provide accurate
,and reliable weather information, and since deviation from the standard may result in less than desired results, economic expediency should not be the sole basis for acceptance ofa
less than desired site location. H􀁯􀁾􀁾􀀠'peter H. Challan Ipirector of Air Traffic V Systems Development Par 6 Page 2 
7/20/98 6560.20B Appendix 1 APPENDIX 1. DRAFT FEDERAL STANDARD FOR SITING METEOROLOGICAL SENSORS AT AIRPORTS FOREWORD The coordina·tion of weather observing activities in the United
States is complex, involving three Federal agencies and the commercial aviation sector. The Departments of Commerce (DOC), Defense (DOD), and Transportation (DOT) all. have programs
to develop and field automated weather observing systems. The automation programs of these three agencies are closely coordinated to manage ·the changes due to automati'on. There is
a critical need to assure commonality and interchangeability of weather information among various Federal and military organizations that provide weather observations. For this reason,
the Office of the FederalCoordin.tor for Meteorological Services and Supporting Research'(OFCM) Working Group for Surface Observations' Task Group for Surface Instrumentation Standards.
has developed siting standards for automated weather observing systems used at airports and heliports. This document addresses siting characteristics for exposure and placement of sensors.
This is essential for the establishment of a standardized meteorological data network, which is necessary for aviation operations, as well· as aviation weather forecasting services.
To provide for an orderly transition to metric units, this document includes both English and metric dimensions. The metric dimensions may not be exact, and until there is an official
changeover to .the metric system, the· English dimensions will prevail. Page i 
6560.20B 7/20/98 Appendix 1 TABLE OF CONTENTS FOREWORD . . . . . i 1. INTRODUCTION. 1" 1.1 PURPOSE. 1 1.2 SCOPE. . 1 2. SENSOR EXPOSURE 3 2. 1 GENERAL. . 3 2.2 PRESSURE SENSOR. 3 2.2.1
Pressure Sensor for Altimeter-Only Systems. 4 . 2.3 CLOUD HEIGHT SENSOR. . .. 4 2.4 VISIBILITY SENSOR. . . 4 2.5 WIND· SENSOR. . . • . . 5 2.6 TEMPERATURE AND DEWPOINT SENSORS 6 2.7
LIGHTNING DETECTION (THUNDERSTORM) SENSOR. 6 2.8 PRECIPITATION TYPE DISCRIMINATION SENSOR 6 2.9 PRECIPITATION OCCURRENCE (YES/NO) SENSOR . 6 2.10 FREEZING RAIN DETECTION SENSOR . . .
. . . 6 2.11 PRECIPITATION ACCUMULATION (LIQUID OR LIQUID EQUIVALENT) SENSOR . . . . . . . . . . . . 7 2.12 SNOWFALL-SNOW DEPTH SENSOR . . . . . . . . . 7 2.13 COMBINATION VISIBILITY,
PRECIPITATION OCCURRENCE, AND PRECIPITATION ACCUMULATION SENSOR. . . 7 3. SITING CRITERIA FOR SENSOR PLACEMENT AT AIRPORTS. 8 3. 1 GENERAL. . . . . . . . . . . . . . . . . . . 8 3.2
CLOUD HEIGHT, VISIBILITY, WIND, TEMPERATURE, DEWPOINT, AND PRECIPITATION SENSORS .. 8 3.2.1 General. . . . . . . . . . . . . . . . 8 3.2.2 Airports with Only Visual and/or Nonprecision
Runways .... ',' ...... 8 3.2.3 Airports with Precision Instrument Runways and Without RVR Instrumentation . . . . . . 9 3.2.3.1 Option #1 ....... . 9 3.2.3.2 Option #2 . . . . . . .
.' . .10 3.2.4 Airports with Precision Instrument Runways and with RVR Instrumentation. . . . 11 Page ii 
7/20/98 6560.20B Appendix 1 3.3 PRESSURE, LIGHTNING DETECTION SENSORS ... 11 3.3.1 Pressure. . . . . . . . . . . . . . 11 3.3.2 Lightning Detection (Thunderstorm). 11 4. HELIPORT SITING
CRITERIA. 13 4.1 NON-AIRPORT HELIPORT SITING CRITERIA.........13 4.2 PRESSURE SENSORS .. .... ....... 13 4.3 SENSORS IN VICINITY OF TAKEOFF AND LANDING AREA. 13 4.3.1 Cloud Height Sensor
14 4.3.2 Visibility Sensor 14 4.3.3 Wind Sensor . . . . 14 4.3.3.1 Wind sensor at ground level heliports . . . 14 4.3.3.2 Wind sensor at rooftop heliports 14 4.3.4 Temperature and Dewpoint
Sensors .. 14 4.3.5 Precipitation Sensor (s) ..... . 14 4.3.6 Lightning Detection (Thunderstorm). 15 ( 4.4 AIRPORT HELIPORT SITING CRITERIA 15 4.4.1 Option ill 15 4.4.2 Option #2 15
4.4.3 Option #3 15 Appendix 2 -Acronyms .. 1 LIST OF FIGURES 1. Precision Instrument Runway Siting (Plan View) .......12 Page iii (and iv) /
( 
7/20/98 6560.20B Appendix 1 1. INTRODUCTION 1.1 PURPOSE This document establishes the Federal 􀁳􀁴􀁡􀁮􀁤􀁾􀁲􀁤􀀠for siting meteorological sensors of automated weather observing systems
at airports/heliports to collect meteorological data to support aircraft operations as well as aviation and other weather forecasting. It will be used by Federal agencies as a basis
for developing and implementing specific regulatory or technical documents. The standard applies'to all Federally-owned and Federally-funded systems, as well as non-Federal systems that
are to be approved by the Federal Aviation Administration (FAA) of the DOT or the National Weather Service (NWS)of the DOC. Multiple users of meteorological data exist, and to the greatest
practical extent they have been considered in the development of this standard. The standard provides criteria for proper and representative exposure of sensors to assure that data are
meteorologically sound (section c). It also provides criteria for selecting locations for sensors at airports (section 3) as well as at heliport installations (section 4). 1.2 SCOPE
This standard is intended to serve as the most fundamental reference for sensor siting. While this document i's not of itself regulatory in nature, it is to be implemented through appropriate
agency orders. Likewise, this standard may be modified or enhanced by agency directives. This document does not require agencies to change existing sensor installations solely to comply
with this standard. It will be applied as new stations are established. Inclusion of sensors in this document does not imply that such sensors will be used in all system applications.
In applying this document to the planning of an automated weather observing system site at an airport with a control tower, no site shall be finalized without obtaining the approval
of the control tower manager or flight service station 􀁭􀁾􀁮􀁡􀁧􀁥􀁲􀀬􀀠as appropriate. Sensor siting in accordance with this standard meets the requirements of Section 77.15(c) of
the Federal Aviation Regulations (FAR) and is exempt from further Part 77 study. Any exceptions to the standard or special situations wi require an FAA obstruction evaluation/airport
airspace analysis (OE/AAA) aeronautical study in accordance with Part 77 of the FAR to determine if a substantial adverse -effect would be created for aircraft operations. Page 1 
6560.20B 7/20/98 Appendix 1 The standard covers the following weather elements: o Surface wind speed and direction o Ambient temperature o Dewpoint temperature o Atmospheric pressure
o Visibility o Sky condition o Precipitation type discrimination (rain, snow, drizzle, etc. ) o Precipitation occurrence (Yes/No) o Freezing precipitation detection o Precipitation accumulation
o Snowfall-snow depth o Lightning detection The standard does not address: o Details of installation for individual manufacturers' sensors o Shielding and/or venting of sensors, except
in general terms o Special application systems such as those designed to detect low-level wind shear o Details of lightning protection Page 2 
7/20/98 6560.20B Appendix 1 2 . SENSOR EXPOSURE 2.1 GENERAL Sensor siting shall not violate runway free areas, runway or taxiway safety areas, or instrument flight procedures surfaces
as or taxiway object obstacle free zones defined in FAA Advisory Circular (AC) 150/5300-13, Airport Design, or FAA Handbook 8260.3, TERPS. Notwithstanding these constraints; the sensor
exposure will strive to minimize or eliminate the effects of,manmade or geographical obstructions. The tower used to mount the wind sensor is not considered an obstruction to the sensor
collection system, but will (with the exception of the temperature, dewpoint, and pressure sensors) be at least 10 feet (3 meters) away from the other sensors. Sensors should be located
as far as practicable from cultivated land to reduce contamination by dust and dirt. It may be necessary to increase the heights of some sensors based on the average maximum snow depth
for the location, which will be determined by averaging the maximum annual snow depths over the period of record. 2.2 PRESSURE SENSOR The pressure sensor will be installed on the airfield,
usually in a weatherproof facility (building, shelter, enclosure, etc.). When the pressure sensor is vented to the outside, a vent header will be used. In most cases, internal venting
of the pressure sensors may be satisfactory. However, if it is determined that internal venting will affect the altimeter setting value by + 0.02 inches of mercury or more, outside venting
will be used. A portable transfer standard will be used to resolve any questions regarding the need for external venting. Siting that will cause pressure variations due to air flow over
the venting interface should be avoided. The venting interface will be designed to avoid and dampen pressure variations and oscillations due to "pumping" or "breathing" of the pressure
sensor venting and porting equipment. Eac;::h sensor will have an independent venting interface from separate outside vents (if outside venting is required) through dedicated piRing
to the sensors. The sensors should also be loc;::ated in an area free of jarring, vibration, and rapid temperature fluc;::tuations (i.e., avoid locations exposed to direct sunlight,
drafts from open windows, air currents from heating or cooling systems, and jet blast). If the pressure sensorS,are sited outdoors, the height of the vent header shall not be less than
one foot above the average maximum snow depth, or 3 feet (1 meter) above ground level, whichever is higher. The field and sensor elevations Page 3 
6560.20B Appendix 1 above Mean Sea Level (MSL) elevation will be determined to the nearest whole foot by a qualified surveyor. The distance between the elevation of the pressure sensors
and the field elevation will not exceed 100 feet (30 meters) . 2.2.1 Pressure Sensor for Altimeter-Only Systems. The criteria in paragraph 2.2 are applicable to altimeter-only systems,
except: (1) The pressure sensor will be installed within 7 nautical miles of the instrument runway thresh'old, and (2) provided a temperature correction is used in the algorithm used
to compute altimeter setting, the elevational difference between the height of the pressure sensors and the field elevation may be increased to 500 feet (150 meters). 2.3 CLOUD HEIGHT
SENSOR This sensor will be mounted on a platform/pedestal with the sensor optics a minimum of 4 feet (1.2 meters) above ground level or above average maximum snow depth, whichever is
higher. The sensor shoUld be located as far as practicable from strobe lights and other modulated light sources. 2.4 VISIBILITY SENSOR This sensor will be mounted on a platform/pedestal
as free as possible from jarring and vibration. Unless otherwise specified by the manufacturer, the receiver will be pointed in a northerly direction. The sensor should be located as
far as practicable from strobe lights and other modulated light sources. The sensor should be located where it .will yield readings that are representative of the visibility on the runway.
It should not be located in an area that is subject to localized obstructions to vision (e.g., smoke, fog, etc.) nor in an area that is usually free of obstructions to vision when they
are present in the surrounding area. It will be mounted so the optics are 10 + 2 feet (3 + 0.6 meters) above ground or 6 feet (2 meters) above the average maximum. snow depth, whichever
is higher. Ten feet (3 meters) above the ground is the preferred height. Keep the area within 6 feet (2 meters) of the sensor free of all vegetation and well drained and any grass or
vegetation within 100 feet (30 meters) of the sensor clipped to a height of about 10 inches (25 centimeters) or less. These precautions are necessary to reduce the probability of carbonbased
aerosols (e.g., terpenes) and insects from interfering with sensor performance. In addition, backscatter-type sensors must have a clear area for 300 feet (90 meters) in the forward (north)
octant. Some sensors may require additional clear areas. The clear line of sight requirement for the sensor optics will be as specified by the sensor manufacturer. Page 4 
7/20/98 6560.20B Appendix 1 2.5 WIND SENSOR . This;,senspr,.."( wind. speed.and wind,·,direction),'wilkbe;):)riented 􀁷􀁩􀁴􀁊􀀺􀁦􀁾􀀬􀁴􀁾􀁾􀁰􀀢􀁾􀀻􀁩􀀻􀁦􀁦􀁣􀀺􀀢􀁾􀀧􀀶􀁜􀀢􀁴􀀧􀁦􀁲􀁩􀁥􀁴􀁨􀁃􀁬􀀺􀁩􀀺􀁴
􀁴􀁬􀁾􀀻􀀬􀂷􀂷􀂷􀂷􀁣􀁔􀁨􀁥􀀻􀂷􀀬􀁳􀁩􀁩􀁦􀀺􀁖􀀮􀁥􀀮􀁹􀀺􀁱􀁲􀀧􀁰􀀶􀁩􀁮􀁴􀀬􀀻􀁻􀁬􀁩􀀮􀁳􀀮􀁥􀁑􀂷􀂷..to;..establ±iili.·. thet!iAWOS;:;·:,;!±ni.l.;/d:Li:.ec.t£.oh"oiiie n t 􀁡􀁴􀁩􀀧􀀸􀁨􀁾􀀻􀀢􀀢􀀻􀁩􀀻􀀬􀁽􀀻
􀁪􀁩􀀻􀁂􀁥􀁾􀀻􀀺􀀡􀀻􀁥􀁲􀁭􀁡􀀺􀁮entry'i"lns'taIled 􀀬􀀮􀀾􀀮􀀧􀀬􀀬􀀺􀀺􀀮􀀧􀀺􀁾􀀧􀀠􀀬􀀻􀀧􀁾􀀻􀁫􀀢􀁾􀁟􀀮􀁟􀁾􀀠.,',',""','-',\ '.'.1".,-: h,';'"-:.',-L:,'_'>"_'>.\ 0:,.",,;-,. '>': -"_':""'-':":"
'''',':''''-'''', ",'" .!.•. ,: 􀁾􀀾... ." ,_., . ,; 􀀮􀁡􀁦􀀡􀁤􀂷􀂷􀀧􀁾􀁲􀁫􀁥􀁱􀀺􀀻􀁡􀀢􀀻􀁾􀀻􀁩􀀡􀀺􀀧􀀡􀀺􀁴􀀺􀀧􀁜􀀧􀁦􀁥􀁲􀀮􀀺􀀧􀁩􀀡􀁲􀁩􀁣􀁥􀀢􀁬􀀺􀀿􀁥􀁨􀀮􀁳􀁬􀀱􀁭􀁡􀀺􀁴􀁾􀁁􀁦􀁯􀁲􀀧􀀯􀁦􀀱􀀮􀀻􀁬􀁾􀁵􀁲􀁥
􀀧􀁵􀁳􀁥􀀬􀀮􀀠The 􀀮􀂷􀁳􀁙􀁓􀀮􀁾􀀵􀀡􀀡􀁬􀁬􀀺􀀱􀀠􀁾􀀠.􀁳􀁯􀁦􀁴􀀬􀁷􀁡􀁲􀁥􀀧􀀮􀀺􀁷􀁾􀁬􀁬􀀼be'lilSedto'􀁭􀁡􀁫􀁥􀁾􀀢􀁲􀁥􀁱􀁱􀁾􀁲􀁥􀁤􀀠.adJustments'·tomagnetlc·· , ,nort.h.Theslte should be'
reranvely level,but small gradual' slopes are acceptable.. The sensor should be mounted at 30 to· 33 teet· (9<tolO,.meters)· above the. average ground height within a radius, .500:fee·t;
d150·.Il)eters). It is de'Sired that all obstructions' (e.g., vegetation, buildings., etc.) be at least 15 feet lower than the height of the sensor within the 500 foot radius and be
no greater than 10 .feet above the se.nsor from 500 to 1000 feet. Where this desired location and clearance is difficult to achieve due to physical or economic reasons, the following
definitions should be followed. An object will become a sheltering obstruction if the distance between the sensor and the object is less than ten times the height of the object and the
lateral angle from the. SElnsor to the enqs. of the object exceeds 10 degrees. 􀁾􀁈􀁩􀀱􀁩􀀡􀁴􀀻􀁩􀀩􀀱􀀺􀀡􀁾􀀧􀂣􀀻􀁩􀀡􀁬􀁩􀁦􀁉􀁧􀀻􀀣􀁴􀀻􀁉􀀿􀀧􀂧􀀧􀁴􀁩􀀧􀁩􀁜􀁵􀁱􀁦􀁯􀀡􀀶􀁗􀁾􀁬􀁲􀀠should
be avoided by location choice or r'Elittb'itg1::f"frbiir;"tn'e''''J::BeatI'on if possible. Again, if difficult to achieve, a less desirable location may have to be selected; but, ''a'E,t.e:r'''4,ns,t
i<!\!4;tatc;;i,'g:n;, the sensor (s) ,.mus.t" demons.tr-a,te" that ,acQur.a.te,.Jiand'";b.eJ"i<>ble.,,,.inLo:!;'ffi.13.t.,t9D_.is being provided. If the wind information is not accurate
and reliable, resolution is required. Resolution may require that the sensors be relocated or turned off. Additional wind sensor siting location information, is covered in paragraphs
3.2.2 and 3.2.3.1 of this order: Exception: The height of a wind sensor installed on the Instrument .Landing System (ILSj glide slope antenna tower or on a separate tower in area !lA,"
figure 1, section 3, 'will be reduced, as necessary, such that the height of the complete wind sensor installation (i.e., to include any required air terminal(s) and obstruction lights)
does not exceed the height of the glide slope antenna installation. The minimum acceptable height for the wind sensor in this situation is 20 feet (6 meters). 􀁾􀁦􀀠side mounting (i.e.,
perpendicular to a tower) is necessary, a boom will be used to permit installation of the sensor at a minimum of· 3 feet (1 meter) laterally from the tower. Side mountingis to be utilized only if top mounting is not practicable and the tower is of open design to allow for free air flow. Page 5 
6560.20B 7/20/98 Appendix 1 2.6 TEMPERATURE AND DEWPOINT SENSORS ., .','􀁔􀁾􀁥􀁳􀁥􀀠senso.l;s will be. 􀁭􀁾􀀩􀁕􀁮􀁾􀁾􀁤􀀠,so 􀁴􀁲􀀮􀀺􀁾􀀺􀁴􀀮...the 􀀬􀁾􀁴􀁾􀁰􀀮􀁩􀀬􀀬􀀺􀀺􀀺􀀻􀀤􀁬􀁹􀁧􀀫􀀺􀁾􀀻􀁩􀁨􀀺􀁜�
�􀁦􀀡􀁾􀀻􀀠,i;;' 􀀬􀀨􀁩􀁦􀀻􀀧􀁾􀀻􀂷􀂷􀁾􀁾􀂷􀁾􀁾􀁾􀀻􀁊􀁜􀀻􀂣􀁩􀀻􀁾􀁾􀀻􀁩􀁉􀀮􀁋􀁾􀁾􀁲􀀦􀁸􀁾􀀺􀀧􀀺􀁾􀁾􀂧􀁾􀀧􀁡􀁾􀁾􀁾􀁾􀁾􀂷􀀧􀀺􀁾􀁾􀁗􀁾􀁾􀁾􀁾􀁾􀁨􀁾􀁴􀁾􀁾􀁦􀂧􀁾􀁾􀀬􀁾􀁾􀁩􀀮􀁾􀂷􀁦􀀤􀀠,,'r
􀁪􀁬􀀺􀀻􀁌􀁧􀁨􀀺􀁾􀀺􀁲􀀻􀀺􀀮􀀠• Five ,feet (1.5:meters)'above.grciundiscthe"·prli;'ferred 􀁨􀁾􀁔􀁧􀁦􀁩􀀧􀁦􀀮􀀠The sensors will be protected from radiati'on fr'ort\ the sun, sky, earth,
and any other surrounding objects, but at the same time, be adequately ventilated. The sensors will be installed in such a position as to ensure that measurements are representative
of the free air circulating in the locality and not influenced by artificial conditioHs such as large buildings, cooling towers, and expanses of concrete and tarmac. Keep any grass and
vegetation within 100 feet (30 meters), of the sensor clipped to height·of about 10 inches (25 centimeters) or'less. 2.7 LIGHTNING DETECTION (THUNDERSTORM) SENSOR This sensor will be
sited and mounted in accordance with the manufacturer's recommendations/specifications. For a single station sensor, metal obstructions will be no closer than two times their hei.ght
above the sensor. 2.8 PRECIPITATION TYPE DISCRIMINATION SENSOR This sensor detects precipitation and discriminates type (e.. g., rain, snow). It will be mounted so that the optics are
10 + 2 feet (3 + 0.6 meters) above ground or 6 feet (2 meters) above the average maximum snow depth, whichever is higher. Ten feet (3 meters) above ground is the preferred height. If
the system is double ended, the optical axis will be oriented generally north-south with the receiver facing north. The terrain between the receiver and transmitter should be relatively
flat. 2.9 PRECIPITATION OCCURRENCE (YES/NO) SENSOR The precipitation occurrence sensor will be mounted in accordance with the manufacturer's specifications. at a convenient height but
not less than 6 feet (2 meters) above ground level or 4 feet (1'.2. meters) above the average maximum snow depth, whichever is higher. Care must be taken to avoid shielding of the sensor
by structures, buildings, and obstacles. 2.10 FREEZING RAIN DETECTION SENSOR The siting requirements for the freezing rain sensor are the same as for the precipitation occurrence sensor.
Page 6 
7/20/98 6560.20B Appendix 1 2.11 PRECIPITATION ACCUMULATION (LIQUID OR LIQUID EQUIVALENT) SENSOR This sensor will be mounted so that the orifice is horizontal and in an area where the
terrain is relatively flat. The orifice is defined as the upper rim edge of the collector mouth. The height of the orifice will be as close to ground level as practicable. In determining
the height of the orifice, consideration will be given to keeping .the orifice above accumulated/drifting snow and minimizing the potential for splashing into the orifice. Surrounding
objects will be no closer. to the· sensor· than a distance equal to two times their height above the gage.orifice. An.object is considered an obstruction if the included lateral angle
from the sensor to the ends of the object is 10 degrees or more. In order to reduce losses due to wind, an alter-type windshield is recommended to be installed on gages in areas where
20 percent or more of the annual average precipitation falls as snow. The surrounding ground can be be covered with short grass or be of gravel, but a hard flat surface such as concrete
gives rise to splashing and should be avoided. Separate sensors may be used to measure liquid and frozen precipitation accumulation (e.g., rain and snow) in which case the above criteria
will be followed for each installation. 2.12 SNOWFALL-SNOW DEPTH SENSOR This sensor will be mounted at least 15 feet (4.5 meters) away from the wind tower over an area which would be
expected to have snow cover which is representative of the area of interest. It will be mounted in accordance with manufacturer specifications and recommendations. 2.13 COMBINATION VISIBILITY,
PRECIPITATION OCCURRENCE, AND PRECIPITATION ACCUMULATION SENSOR The siting requirements for the visibility sensor apply to this combination sensor or any other combinations of the precipitation
parameters and visibility, Page 7 
6560.20B 7/20/98 Appendix 1 ( 3. 􀁓􀁉􀁔􀁾􀁎􀁇􀀠CRITERIA FOR SENSOR PLACEMENT AT AIRPORTS 3.1 GENERAL This section provides criteria for placement of sensors at airports based upon runway
categbry (i.e., visual/nonprecision, preCision without Runway Visual Range (RVR) instrumentation, and precision with RVRinstrumentation). Special care is necessary in selecting appropriate
locations for installation of sensors to assure that the resultant observations are 'representative of the meteorological conditions affecting aviation operations. Users of these criteria
should consider future plans for the airport that could impact placement of sensors, e.g., installation of an Instrument Landing System (ILS), Microwave Landing System (MLS), runway
construction, etc. Critical power availability should also be considered along with all other factors when siting an AWOS. 3.2 CLOUD HEIGHT, VISIBILITY, WIND, TEMPERATURE, DEWPOINT,
AND PRECIPITATION SENSORS ';< '" 3.2.1' >Geb'eral. No sensor sitiiig 􀁳􀁨􀁡􀁬􀁩􀂷􀀻􀀧􀀻􀀭􀀺􀁩􀀮􀀮􀀧􀀶􀀱􀀧􀁡􀁴􀁾􀀺􀁲􀁵􀁲􀁩􀀻􀀻􀁡􀁾􀀻􀁾􀀮􀁲􀀠t!,xi.,ay ! object free areas, runway or, taxiway
safety areas, obstacle" free ;gz.?;be1",f}""'toS'􀀧􀀻􀀧􀀻􀀺􀁾􀁯􀀢􀁾􀀬􀁮􀀬􀀡􀀳􀀬􀀭􀀺􀁾􀀮􀀬􀀻􀀻􀀺􀀬􀀺􀁮􀁾􀁾􀀬􀀬􀀬􀁣􀀴􀁙􀁐􀁴􀁾􀁫􀁴􀀬􀀬􀀬􀀬􀁊􀀺􀁽􀁬􀁪􀁦􀀺􀀮􀀿ced􀁾􀁾􀁽􀁴􀀡􀁬􀁬􀁾􀁾􀀬􀀻􀀺􀀻􀁻􀁢􀁾􀀮􀁾􀀽􀀸􀁩�
�􀀬􀁾􀀻􀀬􀀢􀀽􀀬􀀡􀁩􀁉􀀧􀀻􀀺􀀻􀀡􀁦􀁩􀀢􀁬􀁦􀁩􀁩􀁬􀀢􀀧􀁾"1'\;0,,,, "'5:0"/" ,W 􀀰􀀢􀁏􀁩􀀺􀁬􀀬􀀬􀀬􀀬􀀬􀁾􀀻􀀧􀁁􀀡􀀱􀁬􀀺􀀧􀁲􀁰􀀬􀀬􀀮􀀻􀁲􀁥􀀭􀁮􀁄􀁥􀁳􀁩􀁬􀁩􀀬􀁧􀀬􀀢􀀬􀀠0 r 􀀢􀁾􀀺􀁍􀀮􀀬􀁦􀁴􀁡􀀧􀁡􀁾􀁂􀀮􀀱􀀵􀀧�
�􀀰􀀻􀁬􀁬􀀧􀁩􀀥􀁾􀀧􀀠􀀧􀀧􀀧􀁩􀀶􀀺􀀨􀁩􀀩􀁊􀀧􀀧􀀡􀀧􀀧􀀬􀀧􀀧􀁉􀀧􀀢􀀬􀁾􀀺....:E!R'b'::; • These sensors (cloud height, visibility, wind, temperature, dewpoint, and precipitation) should
be located together near available power and communications. However, the temperature, dewpoint, and precipitation sensors can be placed at any , convenient location on the airport that
meets the sensor exposure criteria outlined in", section 2. The AWOS,'Ilisibil:ity sensor shall not be located in known, areas ,Of, concentrated local', ground fog. These would include
river banks, lake shores, and other locations where at certain times of the year, a small, very localized fog pocket appears that is not an indicator of the overall weather in the area,
and does not obscure the runway. ' FAA SMO Manager approval is required for the use of any FAA ,facilities such as power, communications, shelters, towers,etc. 3.2.2 Airports with Only
Visual and/or Nonprecision Runways. The preferred siting of the cloud height, visibility, and wind sensors and associated data collection platform (DCP) is adjacent to the primary runway
1,000 feet (300 meters) to 3,000 feet (900 meters) down runway from the threshold. The priinar.y"'rtiriway is considered to be the 'runwa:y; wi th the 􀀧􀁩􀀺􀁯􀁷􀁥􀀧􀁳􀁴􀁾􀀺􀀧􀁭􀁩􀁮􀁩􀁭􀁵􀁭􀁳􀁾􀀧􀀻􀀠
The minimum distance from J:'Unwa,YCC<iehteTl-in-e" shall b.e '0'0O:c're',et" (150 meters). The maxlinum'"'di'Eitari'ce from runway centerline shall no:t'exceeQ',l;pOO,::feet (300 meters).
The minimum distance of 500 feet (150 meters) assumes flat terrain. If the elevation of Page 8 
7/20/98 6560.20B Appendix 1 the wind sensor site is above or below the runway elevation, the minimum distance is adjusted by 7 feet for every foot of elevation difference. The adjustment
is negative (i.e., the minimum distance is less than 500 feet) if the sensor site elevation is less than the runway elevation. The adjustment is positive (i.e., the minimum distance
is greater than 500 feet) if the sensor site elevation is greater than the runway elevation. This preferred siting should be appropriate for most airports with only visual and/or nonprecision
runways. Should this siting prove to be unnecessarily restrictive, the cloud height, visibility, and wind sensors and associated DCP may be sited at an alternate location on the airport
provided·the alternate location: (1) will assure that the resultant observations are representative of the touchdown zone of the primary runway, and (2) meets the sensor exposure criteria
outlined in section 2. However, in no case shall the site selected result in a violation of a runway or taxiway object free area, runway or taxiway safety area, obstacle free zone or
instrument flight procedures surface described in AC 150/5300-13, Airport Design, or FAA Handbook 8260.3, TERPS. 3.2.3.1 Option 􀁾􀀱􀀮􀀠The cloud height, visibility, and wind sensors
and associated DCP shall be located adjacent to the primary instrument runway 1,000 feet (300 meters) to 3,000 feet (900 meters) down runway from the threshold. 􀁔􀁨􀁥􀁾􀁾􀁮􀁾􀁲􀁮􀁵􀁭􀀮􀀠distance
&.r.om"''i:ti'll.wa;¥.·..􀁴􀁣􀁾􀁥􀀮􀁄􀀮􀀱􀀻􀁾􀁥􀀬􀀮􀀬􀁊􀁳􀁩􀁩􀁮􀀺􀁥􀀠shall be 􀀺􀀺􀀷􀀭􀀵􀁄􀀬􀀪􀁦􀁾􀁊􀁾􀀮􀁴􀀾􀀠(230 meters) . The 􀁲􀁮􀁡􀀧􀀮􀀡􀁴􀁩􀁲􀁮􀁵􀁭􀀻􀀼􀀴􀁾􀁳􀁊􀀻􀀱􀁴􀁮􀀲􀀮􀁾􀁾􀁦􀁲􀁯􀁭􀀠􀁡􀀺􀀺􀁡
􀀮􀀡􀀮􀀮􀁬􀁬􀁩􀁙􀀮􀁡􀁬􀁦􀀢􀀢􀀢􀁡􀀮􀁥􀁬􀀺􀀴􀀺􀀱􀀺􀁩􀀮􀁥􀀬􀀡􀁬􀀳􀀱􀀮􀁩􀁮􀁾􀁳􀁨􀁡􀁬􀁬􀀠not exceed 􀁵􀀻􀁬􀀮􀂷􀀢􀁣􀀹􀁾􀁪􀁩􀁥􀀬􀁥􀀬􀁴􀁬􀀾􀀢􀀨􀀠300 meters). The mirrimum distance of 750 feet
(230 meters) assumes flat terrain. If the elevation of the wind sensor site is above or below the :runway elevation, the minimum distance adjusted by 7 feet for every foot of elevation
difference. The adjustment is negative (i.e., the minimum distance is less than 750 feet) if the sensor site elevation is less than the runway elevation. The adjustment is positive (i.e.,
the minimum distance is greater than 750 feet) if the sensor site elevation is grea·ter than ·the runway elevation. In no case shall the site result in a violation of a runway or taxiway
object free area, runway or taxiway safety area, obstacle free zone, or instrument ,flight procedures surface as described in 􀁁􀁾􀀵􀁩􀁏􀀺􀀻􀁃􀀵􀁓􀀧􀀨􀁗􀀧􀀻􀀻􀀭􀀢􀀱􀁾􀀢􀀧􀀬􀀠Airport
Design, or FAA 􀁈􀁡􀁮􀁤􀁢􀁯􀁯􀁫􀀧􀀢􀀭􀀸􀀮􀀲􀀶􀀮􀀮􀁯􀀬􀀬􀂷􀀮􀁂􀀩􀁩􀀻􀂷􀁣􀀮􀁔􀀭􀁅􀁒􀀺􀁂􀁾􀀬􀀠Page 9 
6560.20B 7/20/98 Appendix 1 3.2.3.2 Option #2. The cloud height and visibility sensors and associated DCP shall be located behind the glide slope shelter/MLS elevation station used for
the primary precision instrument runway (area "B", figure 1). The wind sensor shall be located either on the glide slope antenna tower.or on a separate tower. The preferre.d. location
is on the glide slope antenna tower as this eliminates the potential safety concernS caused by a separate.wind sensor tdwer. This option shall be implemented at airports that have FAA
Airway Facilities technicians.available and who will not .be relocated as a result of remote maintenance monitoring. Under no conditions shall anyone have access to an FAA glide slope
antenna tower without an FAA technician being present. When mounted on the glide slope antenna tower, the wind sensor shall: (1) not extend above the top of the tower, (2) be mounted
on a boom a minimum of 3 feet (1 meter) laterally from the tower, (3) be a minimum of 3 feet vertically from any antenna, and (4) be mounted on the side of the tower opposite from the
glide slope antenna face. If· jOint use of the glide slope antenna tower is not practical, a separate·wind sensor tower shall be installed immediately behind the glide. slope antenna
tower (area j'A", figure 1). The height of the complete installation (i.e., tower plus air terminal(s) and obstruction lights) shall not exceed the height of the glide slope antenna
tower when installed in this area. Exceptions: Sensors shall not be sited in area "A" or "B", figure I, if the glide slope installation is in violation of a runway or taxiway object
free area, runway or taxiway safety area, obstacle free zone, or instrument flight procedures surface as defined in AC 150/5300-13, Airport Design,or FAA Handbook 8260.3, TERPS. An OE/AAA
study shall be performed if the glide slope installation is decommissioned or relocated subsequent to the siting of the sensors in areas "An and "B", figure 1. One of the above options
should be appropriate appropriate for most airports with precision instrument runways and without RVR instrumentation. Should both options prove to be unnecessarily restrictive, the
cloud height, visibility, and wind sensors and associated DCP may be sited at an alternate location on the airport provided the alternate location: (1) will assure that the resultant
observations are representative of the touchdown zone of the primary instrument runway, and (2) meets the sensor exposure criteria outlined in section 2. However, in no case shall the
site selected result in a violation of a runway or taxiway object free area, runway or taxiway safety area, obstacle Page 10 
7/20/98 6560.20B Appendix 1 free zone, or instrument flight procedures surface as described in AC 150/5300-13, Airport Design, or FAA Handbook 8260.3, TERPS. , , be sited at a location
that will assure the resultant observations are representative of the meteorological conditions affecting aviation operations, and that meets the sensor criteria outlined section 2.
3.3 PRESSURE, LIGHTNING DETECTION SENSORS 3.3.1 pressure. The pressure sensors are not functionally constrained to be at any specific location and may be located anyWhere that meets
the exposure requirements in paragraphs 2.2 and 2.2.1. 3.3.2 Lightning Detection (Thunderstorm). The single station detection sensor shall be installed at any location on the a·irport
that meets the requirements of paragraph 2.7. Page 11 
7/20/98: 6560.20B Appendix 1 e '" -cCo«It:--;(fl a0.,. ....>--4,);;. c:.-In ... <twEet -r-_¢ .. -c::-I 􀁾􀀠 -'if. -􀁾􀀠:..: 􀁾􀀠'" --><: .........--;: Z--c:: Page 12 
7/20/98 6560.20B Appendix 1 4. HELIPORT SITING CRITERIA 4.1 NON-AIRPORT HELIPORT SITING CRITERIA Automated weather observing system installations at nonairport heliport locations shall
place the sensors in the vicinity of the takeoff and landing area, and where helicopter operations will not influence the environment by causing transient sensor performance (e.g., rotor
downwash and blowing dust causing spurious wind and visibility observations) . However, no installation shall penetrate the approach and departure surfaces defined in FAA Handbook 8260.3,
TERPS, or the surfaces defined inAC 150/5390-2, Heliport Design. In choosing a location, consideration will be given to both Visual Flight Rules and Instrument Flight Rules approach
and departure paths and hover/taxi operations. Testing has shown no significant effect on sensors located as close as 100 feet (3·0 meters) from a medium weight helicopter. Another prime
concern is the need to locate the sensors so as to avoid, to the maximum extent possible, conditions (sheltering and other local influences) which may result in unrepresentative weather
observations. This may be a particular problem for heliports located in urban areas and on rooftops. The sensors, except the pressure sensors, should be located no more than 700 feet
(215 meters) from the edge of the takeoff and landing area. The pressure sensor is not constrained to be at any specific location on the heliport, except to be free of rotor-induced
or other pressure variations. The other sensors should be clustered for ease of installation and maintenance, but problems with unrepresentative sensor data or other factors may necessitate
a separated location of a sensor(s). Specific criteria for the siting of individual sensors follows, with siting at airports referring to section 2. 4.2 PRESSURE SENSORS Same as for
airports, except the height above or below MSL shall be determined for the heliport takeoff and landing area. 4.3 SENSORS IN VICINITY OF TAKEOFF AND LANDING 􀁁􀁾􀁅􀁁􀀠These sensors for
cloud height, visibility, wind, temperature/dewpoint, precipitation, lightning detection (thunderstorm) shall be sited as indicated in paragraphs 4.3.1 through 4.3.6. Page 13 
6560.20B 7/20/98 Appendix 1 4.3.1 Cloud Height Sensor. The sensor location is the same as for airports, except the height is with respect to takeoff and landing area. 4.3.2 Visibility
Sensor. The sensor location is the same as for airports, except the height is with respect to the takeoff and landing area. To reduce the influence of dust due to l:.6torwash on the
reported visibility, the visibility sensor should not be sited in a location which is downwind (considering the prevailing wind direction) from th,e takeoff and landing area. 4.3.3 Wind
Sensor. This sensor will be oriented with respect to true north. The system software will be used to make required adjustments to magnetic north. The sensor will be mounted 20-33 feet
(6 to 10 meters) above the heliport takeoff and landing area. If side mounting on a tower is necessary, a boom will be used to permit installation of the sensor a minimum of 3 feet (1
meter) laterally from the tower. Side mounting is to be utilized only if top mounting is not practicable and the tower is of open design to allow for free air flow. 4.3.3.1 Wind Sensor
at Ground Level Heliports. The wind sensor should be located to the side of the preferred approach and departure track. The sensor should be removed from the sheltering influence of
buildings or large trees as per paragraph 2.5 of this order. 4.3.3.2 Wind Sensor at Rooftop Heliports. The wind sensor on a building or other elevated landing structure should be located
at least 20 feet (6 meters) above the highest structure to minimize the Bernoulli effect. Rooftop size may require siting of the wind sensor elsewhere to preclude penetration of an obstacle
identification surface(s). In these situations, siting on an adjacent building may be a viable or even preferred option. It should be noted that many buildings are constructed to the
maximum height that would not constitute a hazard to air navigation. Therefore, the above described siting may not be acceptable from an obstruction evaluation 􀁳􀁴􀁡􀁮􀁤􀁰􀁯􀁾􀁰􀁴􀀮􀀠In
these cases, alternatives such as siting on an adjacent building may be necessary. 4.3.4 Temperature and Dewpoint Sensors. The sensor location is the same as for airports, except the
height is with respect to the takeoff and landing area. 4.3.5 Precipitation Sensor(s). The sensor location is the same as for airports, except the height is with respect to the takeoff
and landing area. Page 14 
7/20/98 6560.20B Appendix 1 4.3.6 Lightning Detection (Thunderstorm). The sensor location is the same as for airports. 4.4 AIRPORT HELIPORT SITING CRITERIA When an automated weather
observing system is to be sited at an airport which has, or is planned to have a heliport, a site should be chosen which will provide service to both runway and heliport users. The following
options, in priority order, will be considered under such circumstances. 4.4.1 Option il. If siting in accordance with the applicable airport siting criteria (section 3) would also comply
with the criteria of paragraph 4.1, the system will be sited in accordance with the applicable airport siting criteria. 4.4.2 Option i2. If siting complying with Option 1 is not appropriate,
consideration will be given to an alternate location if such a location would enhance the representativeness of the data at the heliport without degrading the representativeness of the
data at the primary airport runway. If such an alternate site is selected, a deviation will be processed in accordance with the directives of the responsible agency. 4.4.3 Option i3.
If siting in compliance with Option 1 or 2 is not possible, the system will be sited in accordance with section 3 or paragraph 4.1, taking into consideration such factors as volume of
fixed-wing/helicopter traffic. If siting ,according to paragraph 4.1 is more appropriate, a deviation to use the nonairport siting will be processed in accordance with the responsible
agency's directives. Page 15 (and 16) 
l 7/20/98 AC AWOS DCP DOC DOD DOT FAA FAR ILS MLS MSL NWS OE/AAA OFCM TERPS 6560.20B Appendix 2 APPENDIX 2. ACRONYMS Advisory Circular Automated Weather Observing System Data Collection
Package. Department of Commerce Department of Defense Department of Transportation Federal Aviation Administration Federal Aviation Regulations Instrument Landing System Microwave Landing
System Mean Sea Level National Weather Service Obstruction Evaluation/Airport Airspace Analysis (U.S. standard for) Office of the Federal Coordinator for Meteorological Services and
Supporting Research Terminal Instrument Approved Procedures Page 1 (and 2) 
hl //www.ofcm.gov/siting/text!a-cover.htm (:...... " .. " /«. tpwf>l.. Federal Standard for Siting Mefeorologlcal Sensors at Airports FEDERAL COORDINATOR FOR METEOROLOGICAL SERVICES
AND SUPPORTING RESEARCH 8455 COLESVILLE ROAD, SUITE 1500 SILVER SPRING, MARYLAND 20910 FEDERAL STANDARD FOR SITING METEOROLOGICAL SENSORS AT AIRPORTS FCM-S4-1994 Washington, D.C. August
1994 FOREWORD) 11113103 2: 36 PM 
h, Jlwww.ofcm.gov/siting/text!a-cover.htm The coordination of weather observing activities in the United States is complex. In addition to the Departments of Commerce (DOC), Defense
(DOD), and Transportation (DOT), this effort requires the participation of commercial aViation interests who represent a large segment of the users of meteorological information. This
diversity mandates that the meteorological information distributed among Federal agencies and commercial users comply to established standards. The Office of the Federal Coordinator
for Meteorology (OFCM) through the Working Group for Surface Observations' Task Group for Surface Instrumentation Standards (TG/SIS) has developed standards for siting automated weather
observing systems used at airports and heliports. This document addresses siting characteristics for exposure and placement of sensors. Siting characteristics are essential for the establishment
of a standardized meteorological data network and necessary for aviation and other weather forecasting purposes. While these siting standards define and establish speCifications and
guidelines, they contain sufficient flexibility for agencies to achieve the requirements through agency specific procedures. To provide for an on;lerly transition to metric units, this
document includes both English and metric dimensions. Until there is an official conversion to the metric system, English units will prevail. Julian M. Wright, Jr. Federal Coordinator
c:_ Table of Contents Return to Publications list ) 2 
h, //www.ofcm.gov/siting/texl1d-chapl.htm CHAPTER 1 INTRODUCTION 1.1 PURPOSE. This document establishes the Federal standard for siting meteorological sensors of automated weather observing
systems at airports/heliports to collect meteorological data in support of aircraft operations as well as aviation and other weather forecasting. It will be used by Federal agencies
as a baSis for developing and implementing specific regulatory or technical documents. The standard applies to all Federally-owned and Federally-funded systems, as well as non-Federal
systems that are to be approved by the Department of Transportation's (DOT) Federal AViation Administration (FAA) or the Department of Commerce's (DOC) National Weather Service (NWS).
Multiple users of meteorological data exist, and to the greatest practical extent, they have been considered in the development of this standard. In Chapter 2, the standard provides
criteria for proper and representative exposure of sensors to assure that data are meteorologically sound. Chapter 3 provides criteria for selecting locations for sensors at airports;
Chapter 4 addresses heliport installations. 1.2 SCOPE. This standard is intended to serve as the most fundamental reference for sensor siting. While this document is not of itself regulatory
in nature, it is to be implemented through appropriate agency orders. Likewise, this standard may be modified or enhanced by agency directives. This document does not require agencies
to change existing sensor installations solely to comply with this standard. It will be applied as new stations are established. The inclUSion and description of a particular sensor
in this document does not imply that such sensors will be used in all system ) applications. In applying this document to the planning of an automated weather observing system site at
an airport with a control tower, no site shall be finalized without consulting with representatives of both NWS and FAA. Sensor siting in accordance with this standard meets the requirements
of Section 77.1S(c) of the Federal Aviation Regulations (FAR) and is exempt from further Part 77 study. Any exceptions to the standard or special situations will require an FAA Obstruction
Evaluation/Airport Airspace Analysis (DEIAAA) study in accordance with Part 77 of the FAR to determine if a substantial adverse effect would be created for aircraft operations. The standard
covers the following weather elements: • Surface wind speed and direction • Ambient air temperature • Dew point temperature • Atmospheric pressure • Visibility • Sky condition • Precipitation
type discrimination (rain, snow, drizzle, etc.) • Precipitation occurrence (Yes/No) • Freezing precipitation detection • Precipitation accumulation • Snowfall-snow depth • Lightning
detection 11/13/032:37 PM 2 
hL, J/www.ofcm.gov/siting/text/d-chap1.htm The standard does not address: • Details of installation for individual manufacturers' sensors • Shielding and/or venting of sensors, except
in general terms) • Special application systems such as those designed to detect low-level wind shear • Details of lightning protection Cover Table of Contents Appendix Return to Publications
List 2 11 11 '";tU'l? 'J' '";t7 DM 
ht,. //www.ofcm.gov/siting/texl1e-chap2.htm CHAPTER 2 ) SENSOR EXPOSURE 2_1 GENERAL. Sensor siting shall not violate runway or taxiway object free areas, runway or taxiway safety areas,
obstacle free zones, or instrument flight procedures surfaces as defined in FAA Advisory Circular (AC) 150/5300-13, Airport Design, or FAA Handbook 8260.3, TERPS. Notwithstanding these
constraints, the sensor exposure will strive to minimize or eliminate the effects of manmade or geographical obstructions. The tower used to mount the wind sensor is not considered an
obstruction to the sensor collection system, but it will (with the exception of the temperature, dew point, and pressure sensors) be at least 10 feet (3 meters) away from the other sensors.
Sensors should be located as far as practicable from cultivated land to reduce contamination by dust and dirt. It may be necessary to increase the heights of some sensors based on the
average maximum snow depth for the location, which will be determined by averaging the maximum annual snow depths over the period of record. 2.2 PRESSURE SENSOR. The pressure sensor
will be installed on the airfield, usually in a weatherproof facility (building, shelter, enclosure, etc.). When the pressure sensor is vented to the outside, a vent header will be used.
In most cases, internal venting of the pressure sensors may be satisfactory. However, if it is determined that internal venting will affect the altimeter setting value by ± 0.02 inches
of mercury or more, outside venting will be used. A portable transfer standard will be used to resolve any questions regarding the need for external venting. Siting that will cause pressure
variations due to air flow over the venting interface should be avoided. The venting interface will be designed to avoid and dampen pressure variations and oscillations due to "pumping"
or "breathing" of the ) pressure sensor venting and porting equipment. Each sensor will have an independent venting interface from separate outside vents (if outSide venting is required)
required) through dedicated piping to the sensors. The sensors should also be located in an area free of jarring, Vibration, and rapid temperature fluctuations (i.e., avoid locations
exposed to direct sunlight, drafts from open windows, and air currents from heating or cooling systems). If the pressure sensors are sited outdoors, the height of the vent header shall
not be less than one foot above the average maximum snow depth, or 3 feet (1 meter) above ground level, whichever is higher. Pressure sensor derived values are of critical importance
to aviation safety and operations. Great care shall be taken to ensure that pressure sensor siting is suitable and accurate. The field and sensor elevations above Mean Sea Level (MSL)
elevation shall be determined to the nearest whole footin accordance with agency procedures. The distance between the elevation of the pressure sensors and the field elevation will not exceed 100 feet (30 meters). The above criteria are
applicable to altimeter-only systems, except: (1) 1) the pressure sensor will be installed within 6 miles (9.6 kilometers) of the instrument runway threshold, (2) a temperature correction
is used in the algorithm to compute altimeter setting, and (3) the elevation difference between the height of the pressure sensors and the field elevation may be increased to 500 feet
(150 meters). 2.3 CLOUD HEIGHT SENSOR. The cloud height sensor will be mounted on a platform/pedestal with the sensor optics a minimum of 4 feet (1.2 meters) above ground level or above
maximum snow depth, whichever is higher. The sensor should be located as far as practicable from strobe lights and other modulated light sources. 2.4 VISIBILITY SENSOR. 11/1 􀁾􀀯􀀨􀀩􀁾􀀠'*,:\7
PM 4 
hl I/www.ofcm.gov/siting/text/e-chap2.htm The visibility sensor will be mounted on a platform/pedestal as free as possible from jarring and vibration. Unless otherwise specified by the
manufacturer, the receiver will be pOinted in a northerly direction. The sensor should be located as far as practicable from strobe lights and other ) modulated light sources. It should
neither be located in an area that is subject to localized obstructions to vision (e.g., smoke, fog, etc.) nor in an area that is usually free of obstructions to vision when they are
present in the surrounding area. It will be mounted so the optics are 10 ± 2 feet (3 ± 0.6 meters) above ground or 6 feet (2 meters) above the average maximum snow depth, whichever is
higher. Ten feet (3 meters) above the ground Is the preferred height. The area within 6 feet (2 meters) of the sensor should be free of all vegetation and well-drained. Any grass or
vegetation within 100 feet (30 meters) of the sensor should be clipped to a height of about 10 inches ((25 centimeters). These precautions are necessary to reduce the probability of
carbon-based aerosols (e.g., terpenes) and insects from Interfering with sensor performance. In addition, backscatter-type sensors must have a clear area for 300 feet (90 meters) in
the forward (north) octant. Some sensors may require additional clear areas. The clear line of sight requirement for the sensor optics will be as specified by the sensor manufacturer.
2.5 WIND SENSOR. The wind sensors (wind direction and wind speed) will be oriented with respect to true north. The system software will be used to make required adjustments to magnetic
north. The site should be relatively level, but small gradual slopes are acceptable. It will be mounted 30 to 33 feet (9 to 10 meters) above the average ground height within a radius
of 500 feet (150 meters). The sensor height shall not exceed 33 feet (10 meters) except as necessary to: (a) be at least 15 feet (4.5 meters) above the height of any obstruction (e.g.,
vegetation, buildings, etc.) within a 500 foot (150 meters) radius, and (b), if practical, be at least 10 feet (3 meters) higher than the height of any obstruction outside the 500 foot
(150 meter) radiUS, but within a 1,000 foot (300 meter) radiUS of the wind sensor. An object is considered to be an obstruction if the included lateral angle from the sensor to the ends
of the object is 10 degrees or more. Exception: The height of a wind sensor installed on the Instrument Landing System (ILS) glide slope antenna tower or on a separate tower in area
"An, Figure 1 will be reduced, as necessary, such that the height of the complete wind sensor installation (i.e., to include any required air terminal(s) and obstruction lights) does
not exceed the height of the glide slope antenna installation. The minimum acceptable height for the wind sensor in this situation is 20 feet (6 meters). If side mounting (I.e., perpendicular
to a tower) is necessary, a boom will be used to permit installation of the sensor at a minimum of 3 feet (1 meter) laterally from the tower. Side mounting is to be utilized only if
top mounting is not practicable and the tower is of open design to allow for free air flow. Figure 1 Precision Instrument Runway Siting 2.6 TEMPERATURE AND DEW POINT SENSORS. The temperature
and dew point sensors will be mounted so that the aspirator intake is 5 ± 1 feet (1.5 ± 0.3 meters) above ground level or 2 feet (0.6 meters) above the average maximum snow depth, whichever
is higher, Five feet (1.5 meters) above ground is the preferred height. The sensors will be protected from radiation from the sun, sky, earth, and any other surrounding objects but at
the same time be adequately ventilated. The sensors will be installed in such a position as to ensure that measurements are representative of the free air circulating in the locality
and not influenced by artificial conditions, such as large buildings, cooling towers, and expanses of concrete and tarmac. Any grass and vegetation within 100 feet (30 meters) of the
sensor should be clipped to height of about 10 inches (25 centimeters) or less. 2.7 LIGHTNING DETECTION (THUNDERSTORM) SENSOR. The lightning detection (thunderstorm) sensor will be Sited
and mounted in accordance with the 11/13/032:37 PM 4 
) ) ht,. IIwww.ofcm.gov/sltlng/text/e-chap2.htm manufacturer's recommendations/specifications. For a single station sensor, metal obstructions will be no closer than two times their
height above the sensor. 2.8 PRECIPITATION TYPE DISCRIMINATION SENSOR. The precipitation type discrimination sensor detects precipitation and discriminates type (e.g., rain, snow). It
will be mounted so that the optics are 10 ± 2 feet (3 ± 0.6 meters) above ground or 6 feet (2 meters) above the average maximum snow depth, whichever is higher. Ten feet (3 meters) above
ground is the preferred height. If the system is double ended, the optical axis will be oriented generally north-south with the receiver facing north. The terrain between the receiver
and transmitter should be relatively flat. 2.9 PRECIPITATION OCCURRENCE (YES/NO) SENSOR. The preCipitation occurrence sensor will be mounted in accordance with the manufacturer's speCifications
at a convenient height but not less than 6 feet (2 meters) above ground level or 4 feet (1.2 meters) above the average maximum snow depth, whichever is higher. Care must be taken to
avoid shielding of the sensor by structures, buildings, and other obstacles. 2.10 FREEZING RAIN DETECTION SENSOR. The siting requirements for the freezing rain sensor are the same as
for the preCipitation occurrence sensor. 2.11PRECIPITATION ACCUMULATION {LIQUID OR LIQUID EQUIVALENT} SENSOR. The preCipitation accumulation sensor will be mounted so that the orifice
is horizontal and in an area where the terrain is relatively flat. The orifice is defined as the upper rim edge of the collector mouth. The height of the orifice will be as close to
ground level as practicable. In determining the height of the orifice, consideration will be given to keeping the orifice above accumulated/drifting snow and minimizing the potential
for splashing into the orifice. Surrounding objects will be no closer to the sensor than a distance equal to two times their height above the gage orifice. An object is considered an
obstruction if the included lateral angle from the sensor to the ends of the object is 10 degrees or more. In order to reduce losses due to wind, an alter-type windshield is recommended
to be installed on gages in areas where 20 percent or more of the annual average preCipitation falls as snow. The surrounding ground can be covered with short grass or be of gravel composition,
but a hard flat surface, such as concrete, gives rise to splashing and should be avoided. Separate sensors may be used to measure liqUid and frozen precipitation accumulation (e.g.,
rain and snow) in which case the above criteria will be followed for each installation. 2.12SNOWFALL-SNOW DEPTH SENSOR. The snowfall-snow depth sensor will be mounted at least 15 feet
(4.5 meters) away from the wind tower over an area which would be expected to have snow cover and is representative of the area of interest. It will be mounted in accordance with manufacturer's
specifications and recommendations. 2.13COMBINATION VISIBILITY, PRECIPITATION OCCURRENCE, AND PRECIPITATION ACCUMULATION SENSOR. The Siting requirements for the visibility sensor apply
to this combination sensor or any other combinations of the preCipitation parameters and visibility. Cover Table of Contents 11/13/03 2:37 PM 4 
h .//www.ofcm.gov/siting/text/f-chap3.htm CHAPTER 3 ) SITING CRITERIA FOR SENSOR PLACEMENT AT AIRPORTS 3.1 GENERAL. This Chapter provides criteria For placement of sensors at airports
based upon runway category (i.e., visual/nonprecision, precision without Runway Visual Range (RVR) instrumentation, and precision with RVR instrumentation). Special care is necessary
in selecting appropriate locations for installation of sensors to assure that the resultant observations are representative of the meteorological conditions affecting aviation operations.
Users, in applying these criteria, should consider future plans for the airport that could impact placement of sensors, e.g., installation of an Instrument Landing System (ILS), Microwave
Landing System (MLS), runway construction, etc. The site chosen for locating backup sensors shall be within 11,000 feet (3.4 kilometers) of the primary sensor array and shall have exposure
and terrain equivalent to the primary sensor array site. 3.2 CLOUD HEIGHT, VISIBILITY, WIND, TEMPERATURE, DEW POINT, AND PRECIPITATION SENSORS. 3.2.1 General. No sensor siting shall
violate runway or taxiway object free areas, runway or taxiway safety areas, obstacle free zones, or instrument flight procedures surfaces as described in AC 150/5300-13, Airport Design,
or FAA Handbook 8260.3, TERPS. These sensors (cloud height, visibility, wind, temperature, dew paint, and precipitation) should be located together near available power and communications.
However, the temperature, dew point, and precipitation sensors can be placed at any convenient location on the airport that meets the sensor exposure criteria outlined in Chapter 2.
FAA Sector Manager approval is required for the use of any FAA facilities, such as power, communications, shelters, towers, etc. 3.2.2 Airports with Only Visual and/or Nonprecision Runways.
The preferred siting of the cloud height, visibility, and wind sensors and associated data collection platform (DCP) is adjacent to the primary runway 1,000 feet (300 meters) to 3,000
3,000 feet (900 meters) down the runway from the threshold. The primary runway is considered to be the runway with the lowest minimums. The minimum distance from the runway centerline
shall be 500 feet (150 meters)i the maximum distance shall not exceed 1,000 feet (300 meters). The minimum distance of 500 feet (150 meters) assumes flat terrain. If the elevation of
the wind sensor site is above or below the runway elevation, then the minimum distance is adjusted by 7 feet (2.1 meters) for every foot (0.3 meters) of elevation difference. The adjustment
is negative (i.e., the minimum distance is less than 500 feet [150 meters]) if the sensor site elevation is less than the runway elevation. The adjustment is positive (i.e., the minimum
distance is greater than 500 feet [150 meters]) if the sensor site elevation is greater than the runway elevation. The preferred siting should be appropriate for most airports with only
visual and/or nonprecision runways. If this siting proves to be unnecessarily restrictive, the cioud height, visibility, and wind sensors and associated DCP may be sited at an alternate
location on the airport provided the alternate location: (1) will assure that the resultant observations are representative of the touchdown zone of the primary runway, and (2) meets
the sensor exposure criteria outlined in Chapter 2. In no case shall the site selected result in a violation of a runway or taxiway object free area, runway or taxiway safety area, obstacle
free zone or instrument flight procedures surfaces described in AC 150/5300-13, Airport Design, or FAA Handbook 8260.3, TERPS. 11/13/032:38 PM 3 
\ h. _ ;//www.ofcm.gov/siting/text/f-chap3.htm 3.2.3 Airports with Precision Instrument Runways and Without RVR Instrumentation. There are two preferred options for siting at these airports.
3.2.3.1 Option #1. The cloud height, visibility, and wind sensors and aSSOCiated DCP shall be located adjacent to the primary instrument runway 1,000 feet (300 meters) to 3,000 feet
(900 meters) down the runway from the threshold. The minimum distance from the runway centerline shall be 750 feet (230 meters); the maximum distance shall not exceed 1,000 feet (300
meters). The minimum distance of 750 feet (230 meters) assumes flat terrain. If the elevation of the wind sensor site is above or below the runway elevation, the minimum distance is
adjusted by 7 feet (2.1 meters) for every foot (0.3 meters) of elevation difference. The adjustment is negative (i.e., the minimum distance is less than 700 feet [213 meters]) if the
sensor site elevation is less than the runway elevation. The adjustment is positive (Le., the minimum minimum distance is greater than 750 feet [230 meters]) if the sensor site elevation
is greater than the runway elevation. In no case shall the site result in a violation of a runway or taxiway object free area, runway or taxiway safety area, obstacle free zone, or instrument
flight procedures surfaces as described in AC 150/5300-13, Airport Design, or FAA Handbook 8260.3, TERPS. 3.2.3.2 Option #2. The cloud height and viSibility sensors and associated DCP
shall be located behind the glide slope shelter/MLS elevation station used for the primary precision instrument runway (area "B", Figure 1). The wind sensor shall be located either on
the glide slop antenna tower or on a separate tower. The preferred location is on the glide slope antenna tower as this eliminates the potential safety concerns caused by a separate
wind sensor tower. This option shall be implemented at airports that have FAA Airway Facilities technicians available and who will not be relocated as a result of remote maintenance
monitoring. Under no conditions shall anyone have access to an FAA glide slope antenna tower without an FAA technician being present. When mounted on the glide slope antenna tower, the
wind sensor shall: (1) not extend above the top of the tower, (2) be mounted on a boom a minimum of 3 feet (1 meter) laterally from the tower, (3) be a minimum of 3 feet (1 meter) vertically
from any antenna, and (4) be mounted on the side of the tower opposite from the glide slope antenna face. Ifjoint use of the glide slope antenna tower is not practical, a separate wind
sensor tower shall be installed immediately behind the glide slope antenna tower (area "AU, Figure 1). The height of the complete installation (i.e., tower plus air terminal{s) and obstruction
lights) shall not exceed the height of the glide slope antenna tower when installed in this area. Exceptions: Sensors shall not be sited in area "A" or "B", Figure 1, if the glide slope
installation is in violation of a runway or taxiway object free zone, runway or taxiway safety area, obstacle free zone, or instrument flight procedures surfaces as defined in AC 150/5300-13,
Airport Design, or FAA Handbook 8260.3, TERPS. An OE/AAA study shall be performed if the glide slope installation is decommissioned or relocated subsequent to the siting of the sensors
in areas "A" and "B", Figure 1. One of the above options should be appropriate for most airports with precision instrument runways and without RVR instrumentation. If both options prove
to be unnecessarily restrictive, then the cloud height, visibility, and wind sensors and associated DCP may be sited at an alternate location on the airport provided the alternate location:
(1) will assure that the resultant observations are representative of the touchdown zone of the primary instrument runway and (2) meets the sensor exposure criteria outlined in Chapter
2. In no case shall the site selected result in a violation of a runway or taxiway object free area, runway or taxiway safety area, obstacle free zone, or instrument flight procedures
surfaces as described in AC 150/5300-13, Airport DeSign, or ) FAA Handbook 8260.3, TERPS. 11/13/032:38 PM 3 
h, . ./Iwww.ofcm.gov/siting{text/f-chap3.htm 3.2.4 Airports with Precision Instrument Runways and With RVR Instrumentation. The cloud height, visibility, and wind sensors and associated
DCP shall be sited at a location on the airport that will assure the resultant observations are representative of the meteorological conditions affecting aviation operations, and that
meets the sensor exposure criteria outlined in Chapter 2. No sensor siting shall violate runway or taxiway object free areas, runway or taxiway safety areas, obstacle free zones, or
instrument flight procedures surfaces as described in AC 150/5300-13, Airport Design, or FAA Handbook 8260.3, TERPS. 3.3 PRESSURE, LIGHTNING DETECTION SENSORS. 3.3.1 Pressure. The pressure
sensors are not functionally constrained to be at any speCific location and may be located anywhere that meets the exposure requirements in paragraphs 2.2 and 2.2.1. 3.3.2 Lightning
Detection (Thunderstorm). The single station detection sensor shall be installed at any convenient location on the airport and in accordance with requirements described in paragraph
3.3.2. Cover Table of Contents Appendix Return to Publications List 11/13/03 2:38 PM 
hI. , .flwww.ofcm.gov/sltlng/text/g-chap4.htm ) ) '3 CHAPTER 4 HELIPORT SITING CRITERIA 4.1 NON-AIRPORT HELIPORT SITING CRITERIA. Installation of automated weather observing systems
at non-airport, heliport locations shall place the sensors in the vicinity of the takeoff and landing area, and where helicopter operations will not induce transient sensor performance
(e.g., rotor downwash and blowing dust causing spurious wind and visibility observations). However, no installation shall penetrate the approach and departure surfaces defined in FAA
Handbook 8260.3, TERPS, or the surfaces defined in AC 150/5390-2, Heliport Design. In choosing a location, consideration will be given to both Visual Flight Rules and Instrument Flight
Rules approach and departure paths and hover/taxi operations. Testing has shown no significant effect on sensors located as close as 100 feet (30 meters) from a medium weight helicopter.
Another prime concern is the need to locate the sensors so as to aVOid, to the maximum extent possible, conditions (sheltering and other local influences) which may result in non-representative
weather observations. This may be a particular problem for heliports located in urban areas and on rooftops. The sensors, except the pressure sensors, should be located no more than
700 feet (213 meters) from the edge of the takeoff and landing area. The pressure sensor is not constrained to be at any specific location on the heliport, except to be free of rotor-induced
or other pressure variations. The other sensors should be clustered for ease of installation and maintenance, but problems with non-representative sensor data or other factors may necessitate
a separated location of a sensor(s). SpeCific criteria for the siting of individual sensors follows (siting at airports refers to Chapter 2): 4.2 PRESSURE SENSORS. Same as for siting
at airports, except the height above or below MSL shall be determined for the heliport takeoff and landing area. 4.3 SENSORS IN VICINITY OF TAKEOFF AND LANDING AREA. Cloud height, visibility,
wind, temperature/dew point, preCipitation, lightning detection (thunderstorm) sensors shall be sited as indicated in paragraphs 4.3.1 through 4,3.6. 4.3.1 Cloud Height Sensor. The cloud
height sensor location is the same as for siting at airports, except the height is with respect to the heliport takeoff and landing area. 4.3.2 Visibility Sensor. The visibility sensor
location is the same as for siting at airports, except the height is with respect to the takeoff and landing area. To reduce the influence of dust due to rotorwash on the reported visibility,
the visibility sensor should not be sited in a location which is downwind (considering the prevailing wind direction) from the takeoff and landing area. . 4.3.3 Wind Sensor. 11/13/032:38
PM 
hl _ ./Iwww.ofcm.gov/siting/text/g-chap4.htm The wind sensor will be oriented with respect to true north. The system software will be used to make required adjustments to magnetic north.
The sensor will be mounted 20-33 feet (6-10 meters) above the heliport takeoff and landing area. If side mounting on a tower is necessary, a boom will be used to permit installation
of the sensor a minimum of 3 feet (1 meter) laterally from the tower. Side mounting is to be utilized only if top mounting is not practicable and the tower is of open design to allow
for free air flow. 4.3.3.1 Wind Sensor at Ground Level Heliports. The wind sensor should be located to the side of the preferred approach and departure track should be away from the
sheltering influence of buildings or large trees. 4.3.3.2 Wind Sensor at Rooftop Heliports. The wind sensor on a building or other elevated structure should be located at least 20 feet
(6 meters) above the highest structure to minimize the Bernoulli effect. Rooftop size may require siting of the wind sensor elsewhere to preclude penetration of an obstacle identification
surface(s). In these situations, siting on an adjacent building may be a viable or even preferred option. It should be noted that many buildings are constructed to the maximum height
that would not constitute a hazard to air navigation. Therefore, the above described siting may not be acceptable from an obstruction evaluation standpoint. In these cases, alternatives
such as siting on an adjacent building may be necessary. 4.3.4 Temperature and Dew Point Sensors. The temperature and dew point sensor location is the same as for siting at airports,
except the height is with respect to the heliport takeoff and landing area. 4.3.5 Precipitation Sensor(s). The precipitation sensor location is the same as for siting at airports, except
the height is with respect to the heliport takeoff and landing area. 4.3.6 Lightning Detection (Thunderstorm) Sensor. The lightning detection (thunderstorm) sensor location is the same
as for siting at airports. 4.4 AIRPORT HELIPORT SITING CRITERIA. When an automated weather observing system is to be sited at an airport which has, or is planned to include a heliport,
a site should be chosen which will provide service to both runway and heliport users. The following options, in priority order, will be considered under such circumstances: 4.4.1 Option
#1. If siting in accordance with the applicable airport siting criteria (Chapter 3) would also comply with the criteria of paragraph 4.1, the system will be sited in accordance with
the applicable airport siting criteria. 4.4.2 Option #2. If siting in compliance with Option 1 is not appropriate, consideration will be given to an alternate) location if such a location
would enhance the representativeness of the data at the heliport without 11/13/032:38 PM 3 
h. J/www.ofcm.gov/siting/text/g-chap4.htm degrading the representativeness of the data at the primary airport runway. If such an alternate site is selected, a deviation will be processed
in accordance with the directives of the responsible agency. ) 4.4.3 Option #3. If siting in compliance with Option 1 or 2 is not possible, the system will be sited In accordance with
Chapter 3, or paragraph 4.1, taking into consideration such factors as volume of fixed-wing versus helicopter traffic. If siting in conformance with paragraph 4.1 is more appropriate,
a deviation to use the non-airport siting will be processed in accordance with the directives of the responsible agency. Cover Table of Contents Appendix Return to Publications List
) 11/13/03 2:38 PM 3 
---htt .... /www.ofcm.gov/siting/text/h-appena.htm APPENDIX A ACRONYMS AC AWOS DCl? DOC DOD DOT.. FAA FAR ILS MLS MSL NWS OE/AAA OFCM TERl?S Advisory Circular Automated Weather Observing
System Data Collection Package Department of Commerce Department of Defense Department of Transportation Federal Aviation Administration Federal Aviation Regulations Instrument Landing
System Microwave Landing System 14ean Sea Level National Weather Service Obstruction Evaluation/Airport Airspace Analysis Office of the Federal Coordinator for Meteorological Services
and Supporting Research Terminal Instrument Approved Procedures Cover Table of Contents Return to Publications List 11/13103 2: 38 PM