Compiled by : Ian McMaster & Dave Anderson
This list has been assembled from sources considered reliable, however as with any non-official listing there may at times be one or two corrections that need to be made. If you can contribute any new or updated information please go to the website homepage and click ''e mail the updating team''
A big thank you to the following for their input and feedback:-
Phil Cross; Lawrence Fizia; Steve Martin; Don McLoughlin; Jon; Mark Presswood; Nick; Dave Tuplin;
Rod Webb, Trevor Lloyd, Andy Court, Mick Leahcim, Bones & Paul Jarvis, Trubb (A special thanks for all of the historic data which has completed many gaps), Tom Wylie, Iwan Davies, Chris Globe, Steve Cheeseman, Skywatch, Mike Stanners, Gary Claridge-King, Graham Farish, John Lancaster
Last Update : 28 November 2015
Notes  : Typhoon code changes - There has been some changing of codes,  Visual sightings are recommended on what
seems like possible out of sequence codes being corrected?  I've tried to sumarise the changes in this column, but does prove
difficult at times. The dates are when we have noted them not official change dates. We do recommend VISUAL sightings when
trying to confirm codes, there are some data bases that are using "predicted tie ups" and as we know this IS NOT always the case.
We are pretty sure (as well as we can be, it is hard to keep track of them) that the codes listed and tied up are correct.

Mode S Current 1st noted Was Last noted Notes
43C372 not used 24/11/2011 ZJ946 05/06/2014 confirmed tie up ZJ946 re-coded 43C73E noted from 23/06/14
43C373 not used 17/02/2009 ZJ947 17/06/2014 confirmed tie up ZJ947 re-coded 43C743 noted from 11/12/14
43C378 not used 22/05/2009 ZJ949 03/08/2009 probable tie up ZJ949 re-coded 43C73C but only noted 11/15
43C37A not used             /2009 ZJ950            /2009  probable tie up ZJ950 re-coded 43C73D but only noted 09/15
43C488 ZJ808 13/11/2014 ZJ813 07/11/2014
43C492 ZJ912 21/01/2015 ZJ914 21/07/2014  
43C49D (ZJ923) waiting conf ZJ917 03/12/2014
43C6A9 not used 15/05/2013 ZK380 13/05/2014 confirmed tie up ZK380 re-coded 43C742 noted from 23/06/14
43C6CB ZK315 17/02/2015 ZK343 17/02/2015 both ZK315 & ZK343 were using the same code 12/14- ??/15
          but looks like ZK315 is the only user now 10/15, ZK343 is
using 43CAE3
43C6CF not used 17/04/2014 ZK317 20/11/2014 ZK340 had used this code for a short spell around 12/12 , we think
          still be used by ZK317 but not noted as such since 28/10/14, looks
like a jet that fies around with mode S switched off.
43C6D0 ZJ806 01/10/2015 ZK318   maybe still used by both aircraft? conf required
43C739 ZJ915 14/09/2015 ZK311 04/09/2015 possible ZK311 is op also as 43C739 - ZJ915 to Falklands 14/9/15
43CAE6 not used 22/11/2011 ZK332 04/03/2014 confirmed tie up ZK332 re-coded 43C73F noted from 28/10/14
43CAE7 not used 27/04/2012 ZK333 19/11/2012 confirmed tie up ZK333 re-coded 43C73A noted from 20/11/12
43CAE9 not used 29/05/2012 ZK335 04/03/2013 confirmed tie up ZK335 re-coded 43C746  noted from 26/09/14
43CAEA not used 18/10/2012 ZK336 28/08/2014 confirmed tie up ZK336 re-coded 43C747  noted from 08/10/14
43CAEB not used 27/03/2012 ZK337 27/03/2012 confirmed tie up ZK337 re-coded 43C748  noted from 05/11/12
43CAEC not used 25/10/2012 ZK338 26/02/2013 confirmed tie up ZK338 re-coded 43C749  noted from 02/10/14
Hex Code Regn. A/C Type Date Remarks
43C6F2     05/03/2015 Active noted for 1st time, no more detail
43C758 (ZZ511) Wildcat AH1 09/03/2015 Predicted sequence serial TBC
43C75A (ZZ513) Wildcat HMA2 28/04/2015 Predicted sequence serial TBC
43C339   Watchkeeper 07/05/2015 Reported as a Thales Watchkeeper UAV nr Aberporth range.
43C80D   Watchkeeper 03/06/2015 Noted operating from Boscombe Down
43C672 (ZF143) Tucano T1 31/07/2015 Noted 1st time as "LOP30" serial TBC
43C66D (ZF135) Tucano T1 08/10/2015 Noted 1st time as "LOP10" serial from predicted sequence
43C73F ZK332 Typhoon FGR4 08/10/2015 Noted as "Pyscho 21" and on 12/10 as "LOS33"
43C7CD ZK550 Chinook HC5 09/10/2015 Noted flying as SHF498
43C799 ZK371 Typhoon FGR4 09/10/2015 Noted on a test flight from Warton, aircraft test flew that day
43C6D0 ZJ806 Typhoon FGR4 01/10/2015 Re-code or misscode noted CGY see notes above was 43C486
43C7B9 ZK608 Typhoon EFA 12/10/2015 Noted on a test flight from Warton as "WTN29" 
43C4B2 ZJ944 Typhoon FGR4 15/10/2015 Noted flying from Coningsby
43C6F0   Watchkeeper 16/10/2015 Noted in the Boscombe Down area "Aries" in c/sign box
43C678 (ZF172) Tucano T1 19/10/2015 Noted 1st time as "LOP15" serial from predicted sequence
43C4B2 ZJ944 Typhoon FGR4 21/10/2015 Noted flying from Coningsby serial confirmed
43C7BA ZK609 Typhoon EFA 29/10/2015 Noted on a test flight from Warton 
43C763 ZZ522 Wildcat AH1 22/11/2015 Noted as WHE01 on 2/10 & WHE02 on 15/10
43C764 ZZ523 Wildcat AH1 22/11/2015 Noted as "ZZ523" on 12/10
43C765 ZZ524 Wildcat AH1 22/11/2015 Flown on 16/11 from predicted sequence
43C7BB ZK610 Typhoon EFA 24/11/2015 Noted on a test flight from Warton as "ZK610" 
43C73C ZJ949 Typhoon FGR4 25/11/15 Long awaited gap filler! noted at Coningsby

(If you are aware that any of the Conflicts have been fixed please E Mail the Updating Team)
Hex Code Regn. A/C Type Date Remarks
000001   A330 Voyager 13/04/2014 Used by a number of aircraft including USAFE F15's
000100   Tornado GR4 25/03/2013 Noted as Saxon 1 (25/03/13) & Vandal 01 (26/03/13) - Not an Indian IL76
000359 ZJ954 Puma HC1 05/01/2015 Noted as Vortex 331 13/01/15
000AD3 ZJ925 Typhoon FGR4 23/03/2015 Two using the same code see below both noted 08/04/15
000AD3 ZJ937 Typhoon FGR4 08/04/2015 see above
03C059 ZA541 Tornado GR4 04/10/2012 Should be using 43C159
03C16D ZA556 Tornado GR4 06/12/2012 Operating as WTN21 Lossiemouth-Marham (Ferry Flight)
03CB5A ZZ513 Wildcat 29/09/2015 Should be 43C75A
053977 ZK001 Merlin HC3 25/08/2012 Should be using code 43C617
249249   Various 12/01/2013 Used by a number of UK aircraft including Sea King, Merlin, Typhoon
260701   Typhoon 09/04/2014 Bae Systems trials aircraft. Used on many different airframes
42726F (ZJ186/ZJ218) Apache AH1 07/05/2015 Possible one of two aircraft
436CA9   Helicopter 24/04/2014 Noted as 'SHF010'
438613 ZJ990 Merlin HC3A 22/07/2015 Noted with serial in callsign box
43C01B ZE389 Helicopter 19/06/2014 Old Tornado F3 code, may now be used by a Chinook HC6
43C06C ZJ117 Merlin HC3 02/10/2014 Noted with ZJ120 in the callsign box - Serial T.B.C.
43C139 XW665 Nimrod (Not) 07/05/2013 Noted active again. Not a Nimrod as the rego. Would suggest
43C14B ZG707 Tornado GR4 30/10/2012 Is also a C130 C4 ZH868 which also uses this code, the GR4 however fits the expected sequence.
43C1BF ZD739 Tornado GR4 20/02/2013 Should be coded 43C1BA
43C1E4 ZJ705 / ZJ136 B412 / Merlin 20/10/2013 ZJ136 has been noted recently using the code allocated to ZJ705
43C1F9 ZJ133 Merlin HC3 14/08/2012 Was noted flying with ZJ134 in the callsign box on SBS
43C225 ZJ130 Merlin HC3 09/12/2013 Was noted flying with ZJ122 in the callsign box on SBS
43C25E ZJ166 Apache AH1 28/03/2012 Visual sighting of ZJ173 using this code, but still used by ZJ166
43C26B ZJ214 Apache AH1 02/09/2013 Visual sighting of ZJ214 using this code
43C2CE XZ726 Lynx HMA8 06/08/2012 Noted flying with XZ731 in the SBS callsign box
43C2D0 XZ729 Lynx HMA8 21/07/2013 Noted flying with XZ729 in the SBS callsign box
43C2FB ZJ990 Merlin HC3A 06/11/2012 Interin code for ex Danish AF machine - recoded 43C612
43C2FC ZJ992 Merlin HC3A 06/11/2012 Interin code for ex Danish AF machine - recoded 43C613
43C2FD ZJ994 Merlin HC3A 06/11/2012 Interin code for ex Danish AF machine - recoded 43C614
43C2FE ZJ995 Merlin HC3A 06/11/2012 Interin code for ex Danish AF machine - recoded 43C615
43C2FF ZJ998 Merlin HC3A 06/11/2012 Interin code for ex Danish AF machine - recoded 43C616
43C300 ZK001 Merlin HC3A 06/11/2012 Interin code for ex Danish AF machine - recoded 43C617, also used by AACHF XP820 & XT626 not sure which is current
43C317 ZH845 Merlin HM2 05/09/2015 Noted as ZH824 at Prestwick
43C326 ZH860 C130J Hercules 25/05/2012 Noted around the Galashiels area with ZH828 in the SBS c/s box
43C451 XX317 Hawk T1A (F) 10/10/2008 Mode-S reported as being 43C450 which is allocated to XX316
43C45A (XX326) Hawk T1A 11/10/2012 Hawk climbing out of Leeming using this Hex Code , however XX326 is stored at Shawbury (front section only)
43C4F8 XZ208 Lynx AH7 25/04/2012 Was noted as a Chinook
43C549 ZG919 Lynx AH9 15/04/2012 Was noted with XZ729 in the callsign box on SBS
43C59F ZM405 Atlas C1 18/09/2015 Miss coded for 43C5DF (also used 43C6DF!)
43C613 ZJ992 Merlin HC3 20/04/2012 Noted at Cranfield with ZJ992 in the SBS c/s box so has there been a code change ?
43C614 ZJ994 Merlin HC3 17/04/2012 Was noted at Cranfield with ZJ992 in the c/s box & quoted by pilot to ATC as ZJ992
43C62A (XZ597) Sea King HAR3 17/10/2013 Was noted flying in the Valley Area with XZ598 in the callsign box
43C62B (XZ598) Sea King HAR3 30/09/2013 Was noted flying in the Valley Area with XZ599 in the callsign box
43C62C (XZ599) Sea King HAR3 30/09/2013 See note above re 43C62B
43C633 (ZK542) Seaking HAR3 11/11/2014 Code used by Typhoon "LOS11" possibly ZK348
43C719 ZJ272 & ZJ273 Squirrel HT1 29/01/2013 Same code on both aircraft when airborne at the same time
43C72E ZJ246 Squirrel HT1 18/09/2013 Was noted flying as ZJ244
43C739 ZJZ915 Typhoon FGR4 14/09/2015 Possible ZK311 is op also as 43C739 - ZJ915 to Falklands 14/9/15
43CB58 ZZ511 Wildcat AH1 21/10/2015 Should be 43C758
43CB0B ZK382 Typhoon FGR4 09/05/2013 Noted with Winston 41 as the callsign
AAAAAA Various Typhoon   Various Factory default setting for many Mode-S Boxes on newly delivered aircraft.
C3C361 ZA299 Sea King HC4 15/02/2011 Has been flying with this code since 03/11 with Fly Navy in c/s box
E3C283 XW199 Puma HC1 22/07/2015 Misscoded noted Leeming s/be 43C283
(XV249) Registration in brackets = Forecast allocation based on a pattern to allocations but not a confirmed allocation
XV249 Registration in 'Bold Red text' is a registration or allocation that may be suspect due to mode-s box swapping etc.
XV249 Registration & Aircraft Type with 'Strike through' = Allocation not now carried by that aircraft. IE A/C wfu or w/o