Editing Aviation light signals (section)

{{Short description|Use of visible electromagnetic radiation to conduct air traffic control}}
[[File:Air Traffic Control Journeyman, SENIOR AIRMAN Bryan Greenwood of the 86th Operation Support Squadron does a maintenance check on a light gun which allows planes to land safely if th - DPLA - 8ade36e34b217823f71235bfe18c36c2.jpeg|thumb|right|A [[United States Air Force]] [[airman]] with a signal light gun that can be used to control aircraft with radio failure.]][[File:Signal Light Gun Hulbert Field.jpg|thumb|right|Air traffic control signal light gun in use at base flight tower]]
In the case of a [[NORDO|radio failure]] or [[aircraft]] not equipped with a radio, or in the case of a deaf pilot, [[air traffic control]] may use a [[signal lamp]] (called a "signal light gun" or "light gun" by the [[FAA]]<ref name="FAA2214" /><ref name="FAATbl431">{{cite web |title=TBL 4-3-1, Airport Traffic Control Tower Light Gun Signals |url=https://www.faa.gov/air_traffic/publications/atpubs/aim_html/chap4_section_3.html#TBL_4_3_1 |website=Section 3. Airport Operations |publisher=Federal Aviation Administration |accessdate=12 May 2019}}</ref>) to direct the aircraft. [[ICAO]] regulations require air traffic control towers to possess such signal lamps.<ref name="ICAOannex14V1513">{{cite book |title=Aerodromes: Volume I Aerodrome Design and Operations |date=July 2013 |publisher=International Civil Aviation Organization |page=8-2 |edition=6th}}</ref><ref name="Bahrain">{{cite book |title=Civil Aviation Regulations (CAR 001 – Aerodrome Standards & Certification Regulations) 2018 |date=April 19, 2018 |publisher=Kingdom of Bahrain Ministry of Transportation and Telecommunications |page=68 |url=http://www.transportation.gov.bh/sites/default/files/car001_2018_0.pdf |access-date=May 12, 2019 |archive-date=September 25, 2020 |archive-url=https://web.archive.org/web/20200925233159/http://transportation.gov.bh/sites/default/files/car001_2018_0.pdf |url-status=dead }}</ref> The signal lamp has a focused bright beam and is capable of emitting three different colors: red, white and green.<ref name="ICAO2" /><ref name="FAA4313">{{cite web |title=4-3-13. Traffic Control Light Signals |url=https://www.faa.gov/air_traffic/publications/atpubs/aim_html/chap4_section_3.html |website=Section 3. Airport Operations |publisher=Federal Aviation Administration |accessdate=12 May 2019}}</ref> These colors may be flashed or steady, and have different meanings to aircraft in flight or on the ground.<ref name="ICAO2" /><ref name="FAATbl431" /><ref name="EURlex">{{cite web |title=3. SIGNALS FOR AERODROME TRAFFIC |url=https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=celex:32012R0923 |website=EUR-Lex |publisher=European Union |accessdate=12 May 2019}}</ref> Planes can acknowledge the instruction by rocking their wings, moving the [[aileron]]s if on the ground, or by flashing their landing or navigation lights during hours of darkness.<ref name="FAA4313" /><ref name="EURlex" /> Air traffic control signal light guns are typically specified with a (white) center beam brightness of > 180,000 - 200,000 candela,<ref name="FAA2214">{{cite book |last1=Federal Aviation Administration |title=Gun, Signal Light, Portable, FAA-E-2214a Amendment-2 |date=July 5, 1973 |publisher=Department of Transportation |page=5 |url=https://faaco.faa.gov/index.cfm/attachment/download/22930 |accessdate=30 Apr 2017 |archive-url=https://web.archive.org/web/20170430215936/https://faaco.faa.gov/index.cfm/attachment/download/22930 |archive-date=30 April 2017 |url-status=live}}</ref><ref name="MIL25971D">{{cite book |title=Light, Airport Traffic Control, SDU-4/U, MIL-DTL-25971D |date=February 18, 2015 |publisher=Department of Defense |page=7 |url=http://quicksearch.dla.mil/qsDocDetails.aspx?ident_number=18207 |accessdate=12 May 2019 |archive-date=12 May 2019 |archive-url=https://web.archive.org/web/20190512011611/https://quicksearch.dla.mil/qsDocDetails.aspx?ident_number=18207 |url-status=dead }}</ref><ref name="RuckerRFP">{{cite web |last1=MICC Fort Rucker |title=58--Tower Signal Light Guns |url=https://www.usaopps.com/government_bids/detail/ADP14422440980000347.htm |website=USAOPPS |accessdate=12 May 2019}}</ref> and are visible for roughly 4 miles in clear daylight conditions.<ref name="RuckerRFP" /><ref name="ATI">{{cite web |title=Signal Light Gun |url=http://atiavionics.com/ |publisher=ATI Avionics, Inc. |accessdate=12 May 2019}}</ref><ref name="PPSTech">{{cite web |title=LED Signal Light Gun |url=http://www.signallightgun.com/ |publisher=PPS Technical |accessdate=12 May 2019}}</ref> The table below describes the meaning of the signals.<ref name="ICAO2">{{cite book |title=Rules of the Air: Annex 2 to the Convention on International Civil Aviation|date=July 2005 |publisher=International Civil Aviation Organization |page=APP 1–3 |edition=10th |url=http://www.icao.int/Meetings/anconf12/Document%20Archive/an02_cons%5B1%5D.pdf |accessdate=12 May 2019}}</ref><ref name="FAATbl431" /><ref name="EURlex" /> The use of handheld combination red/green/white signal lamps for air traffic control dates back to at least the 1930s.<ref name="US2085020">{{cite book |last1=Harding |first1=W |title=US Patent 2,085,020 Combination Sight and Indicator for Traffic Control Projectors |date=June 29, 1937 |publisher=USPTO |url=https://patents.google.com/patent/US2085020A/en |accessdate=13 May 2019}}</ref>
{| class="wikitable"
|-
! Signal !! Aircraft in flight !! Aircraft on the ground !! Ground vehicles or personnel
|-
! Flashing white
| [[ICAO]] – Land at this airport and proceed to apron (this is not a clearance to either land or taxi. Clearances to land and taxi will follow.)<br />
[[FAA]] – Not applicable
| Return to starting point on airport
| Return to starting point on airport 
|-
! Steady green
| Cleared to land || Cleared for takeoff || Cleared to cross, proceed or go
|-
! Flashing green
| Return for landing || Cleared to taxi || Not applicable
|-
! Steady red
| Give way to other aircraft and continue circling ||STOP||STOP
|-
! Flashing red
| Airport unsafe, do not land || Taxi clear of the runway in use || Clear the taxiway/runway
|-
! Alternating red and green
|Exercise extreme caution ||Exercise extreme caution ||Exercise extreme caution
|-
|}

{{Telecommunications}}