UK317 flight simulator community.  In partnership with Western Air, ATCMagic, Heritage Flight

Server IP number

Home | BOT Commands | Events | Rules | Server information | FSX Notes | TS3 chat room | WAA

UK317 sends out a regular bulletin of server events, if you wish to be added to this list please send an e-mail to: Derek317 (Derek Haselden)


Real world aviation transponder codes are issued to flights from a block or set of numbers allocated to each ATC zone, area, facility, or section, with some flights using codes reserved specifically for their aviation function.  In many cases the squawk code issued to a flight will stay with that aircraft for the duration of its flight.  The same codes can also be used in FSX if desired and indeed many FSX ATC’s utilise real world aviation transponder codes.  However, while transponder (squawk) codes in FSX can be used to replicate real world aviation these numbers can be somewhat arbitrary and have little other use as such.  With 4096 possible numeric codes this simple function in FSX can be made to work a little harder if desired…


UK317 sometimes operates a simple system of transponder codes to help identify and remind ATC what an aircraft will be doing.  Thus not only is an aircraft assigned a code, that code can assist pilots and ATC remember what a particular aircraft is doing.  If you fly under ATC direction in the server you may be issued with a transponder code that may not immediately make sense but it does in fact have a true function.  If you are a pilot and have not been issued with a squawk code, and have not filed a flight plan, you may use the codes below to indicate to any ATC present your intentions if you wish.

Code          Rules         Flight         Intentions

0000           -                  -                  Squawk identification.  (Used to help ATC identify your aircraft if your transponder does NOT have ident button.)  # See Note 1.


1###           IFR             Inbound     Flying towards and into an ATC controlled airfield.  (# See Note 2.)

1200           VFR            -                  FSX default transponder code, VFR if no other code has been assigned (US & Canada).  [Real world aviation code.]

2###           IFR             Outbound Flying away from an ATC controlled airfield.  (# See Note 2.)

3###           IFR             Transit       Flying across or between ATC controlled airfields.  (# See Note 3.)

4000           IFR             -                  Flying IFR within or close to controlled airspace but NOT in a standard circuit.  (#See Note 4)

4010           IFR             Circuits     Flying IFR circuits at an ATC controlled airfield.  [Special code for use with UK317 server and UK Radar v1.3.1]  (#See Note 4)


5###           VFR            Inbound     Visual flight, no traffic service, approaching controlled airspace.  (# See Note 5.)

6###           VFR            Outbound Visual flight, no traffic service, exiting and remaining outside controlled airspace.  (# See Note 5.)

7000           VFR            -                  Special code – Conspicuity, VFR if no other code has been assigned (UK).  [Real world aviation code.]  (# See Note 5.)

7010           VFR            Circuits     Circuits / operating within an aerodrome traffic pattern (UK).  [Real world aviation code.]


7500           -                  -                  Special code: Hijack.  [Real world aviation code.]

7600           -                  -                  Special code: Radio failure.  [Real world aviation code.]

7700           -                  -                  Special code: Emergency.  [Real world aviation code.]

7777           -                  -                  Special code: Mayday.  [Real world aviation code (US).]


·         # Note 1.  Selecting code ‘0000’, or pressing the ‘Ident’ button on your transponder (if fitted), will cause your aircraft tag on FSX radar to flash red instead of the normal yellow.  This will draw the attention of ATC to your aircraft and can help ATC identify your aircraft on screen.  But note that it may unnecessarily distract the ATC and you should not leave your transponder set to ‘0000’ unless specifically requested.  (A functioning ‘Ident’ button on a transponder will self cancel after several seconds.)

·         # Note 2.  The ICAO airfield code coming first alphabetically is deemed to be the inbound airfield.  So for example, if flying from EGHI to EGNX (outbound) you would squawk 2###, if flying to EGHI from EGNX (inbound) you would squawk 1###.

·         # Note 3.  Code used when flight does not involve take-off or landing at an ATC controlled airfield but flight requires contact with ATC due to entering controlled airspace.

·         # Note 4.  A standard circuit, that is:  Upwind/Runway, crosswind, downwind, base, final.

·         # Note 5.  While the flight being conducted is VFR the pilot may of course request an ATC service where available.

UK317 supplemental / special transponder codes

The following codes may be used to indicate the nature of a flight and these additional codes closely replicate UK real world transponder codes, please feel free to use them…






0016, 0017

Medical Evacuation, Air Ambulance


Military low level conspicuity / climbout

0023, 0024

Search and Rescue


Flights within Danger Areas


NATO, Military operations


Red Arrows


NATO, Military operations




NATO, Military operations


Aircraft conducting high energy manoeuvres


NATO, Military operations

7006, 7007

Observation and monitoring flights


NATO, Military operations

7400 – 7407

Civil contingency, Airlift, Surveys


NATO, Military operations




NATO, Military operations



airsim.jpg  FSXM Logo.png  airbourne.jpg

© Derek Haselden 2018