sensors Mode-S transponder

4081BB

ICAO 24-bit transponder address · allocated to United Kingdom

Currently assigned to G-TNEF · AIRBUS A-321neo

Hex
4081BB
Octal
20100673
Decimal
4,227,515
Country
GB
Tail
G-TNEF
Type
A21N
No current signal · last broadcast 13h ago
Flights observed
13
Distinct callsigns
9
Country
GB
Last broadcast
13h ago

Last known position

Most recent position reported by Mode-S 4081BB.

Country allocation

The ICAO 24-bit address 4081BB falls within the block assigned to United Kingdom (GB) by ICAO Annex 10, Volume III. Every aircraft registered in United Kingdom receives a permanent address from this block at the time of registration; the address stays with the airframe even if the aircraft is re-registered to a different operator within the country.

Callsign history 9 distinct

Callsign Airline Flights Last seen
BAW509 - 3 2026-04-13
BAW990G British Airways 2 2026-04-13
BAW568J - 2 2026-04-14
BAW938 - 1 2026-04-13
BAW91J - 1 2026-04-13
BAW63VP - 1 2026-04-12
BAW569J British Airways 1 2026-04-14
BAW508 - 1 2026-04-12
BAW3XA British Airways 1 2026-04-13

Recent flights last 13

DateFlightRouteTakeoffLandingDuration
2026-04-14 BAW569J LIN → LHR Apr 14, 09:25 UTCApr 14, 11:00 UTC1h 35m
2026-04-14 BAW568J - Apr 14, 07:10 UTCApr 14, 08:20 UTC1h 10m
2026-04-14 BAW568J - Apr 14, 06:45 UTCApr 14, 07:10 UTC25m
2026-04-13 BAW3XA DUS → LHR Apr 13, 20:30 UTCApr 13, 21:50 UTC1h 20m
2026-04-13 BAW938 - Apr 13, 17:35 UTCApr 13, 18:55 UTC1h 20m
2026-04-13 BAW91J BER → LHR Apr 13, 13:45 UTCApr 13, 15:10 UTC1h 25m
2026-04-13 BAW990G LHR → BER Apr 13, 11:55 UTCApr 13, 12:20 UTC25m
2026-04-13 BAW990G LHR → BER Apr 13, 10:50 UTCApr 13, 12:15 UTC1h 25m
2026-04-13 BAW509 - Apr 13, 08:20 UTCApr 13, 09:05 UTC45m
2026-04-13 BAW509 - Apr 13, 07:55 UTCApr 13, 09:05 UTC1h 10m
2026-04-13 BAW509 - Apr 13, 06:40 UTCApr 13, 08:15 UTC1h 35m
2026-04-12 BAW508 - Apr 12, 19:40 UTCApr 12, 20:15 UTC35m
2026-04-12 BAW63VP - Apr 12, 17:15 UTCApr 12, 17:30 UTC15m

About Mode-S

A Mode-S transponder code (also called an "ICAO 24-bit address" or "hex code") is a 6-character hexadecimal identifier permanently assigned to an aircraft when it's first registered. Unlike callsigns (which change with each flight) or registrations (which can change if an aircraft is sold internationally), the Mode-S address stays with the airframe for the life of the aircraft in that country.

Every ADS-B transmission from an aircraft includes its Mode-S address, making it the most reliable way to identify a specific airframe. Flight-tracking services like Apparatus use the Mode-S address as the primary key for tying position broadcasts, callsigns, and ownership records together.

Prefer a tail-number view? See the G-TNEF page for operator, model, and routing details .

Mode-S 4081BB frequently asked

What is Mode-S code 4081BB?
4081BB is an ICAO 24-bit transponder address. Allocated to United Kingdom. Assigned to G-TNEF.
Where is Mode-S 4081BB registered?
Mode-S code 4081BB is allocated to United Kingdom (GB). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 4081BB broadcasting right now?
No active broadcast right now. Last signal was 13h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 4081BB, octal 20100673, decimal 4,227,515.
What flights does 4081BB operate?
Mode-S 4081BB has broadcast 9 distinct callsigns, including BAW509, BAW990G, BAW568J, BAW938, BAW91J.