Apparatus

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sensors Mode-S transponder

424A71

ICAO 24-bit transponder address · allocated to United Kingdom

Currently assigned to TWR

Hex
424A71
Octal
20445161
Decimal
4,344,433
Country
GB
Tail
TWR
Type
TWR
No current signal · last broadcast 23d ago
Flights observed
54
Distinct callsigns
1
Country
GB
Last broadcast
23d ago

Last known position

Most recent position reported by Mode-S 424A71.

Country allocation

The ICAO 24-bit address 424A71 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 1 distinct

Callsign Airline Flights Last seen
ID424A71 - 54 2026-06-29

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-06-29 ID424A71 - Jun 29, 12:00 UTCJun 30, 03:15 UTC15h 15m
2026-06-23 ID424A71 - Jun 23, 08:20 UTCJun 24, 02:54 UTC18h 35m
2026-06-23 ID424A71 - Jun 23, 06:19 UTCJun 24, 02:54 UTC20h 35m
2026-06-23 ID424A71 - Jun 23, 04:19 UTCJun 24, 02:54 UTC22h 35m
2026-06-23 ID424A71 - Jun 23, 02:20 UTCJun 24, 02:15 UTC23h 55m
2026-06-22 ID424A71 - Jun 22, 22:19 UTCJun 23, 22:15 UTC23h 55m
2026-06-22 ID424A71 - Jun 22, 20:19 UTCJun 23, 20:15 UTC23h 55m
2026-06-22 ID424A71 - Jun 22, 18:19 UTCJun 23, 18:14 UTC23h 55m
2026-06-22 ID424A71 - Jun 22, 16:20 UTCJun 23, 16:14 UTC23h 55m
2026-06-22 ID424A71 - Jun 22, 14:19 UTCJun 23, 14:15 UTC23h 55m
2026-06-22 ID424A71 - Jun 22, 12:19 UTCJun 23, 12:15 UTC23h 55m
2026-06-22 ID424A71 - Jun 22, 10:19 UTCJun 23, 10:15 UTC23h 55m
2026-06-22 ID424A71 - Jun 22, 06:19 UTCJun 23, 06:15 UTC23h 55m
2026-06-22 ID424A71 - Jun 22, 04:19 UTCJun 23, 04:14 UTC23h 55m
2026-06-22 ID424A71 - Jun 22, 02:19 UTCJun 23, 02:15 UTC23h 55m
2026-06-22 ID424A71 - Jun 22, 00:20 UTCJun 23, 00:15 UTC23h 55m
2026-06-21 ID424A71 - Jun 21, 22:20 UTCJun 22, 22:15 UTC23h 55m
2026-06-21 ID424A71 - Jun 21, 20:24 UTCJun 22, 20:14 UTC23h 50m
2026-06-21 ID424A71 - Jun 21, 18:20 UTCJun 22, 18:15 UTC23h 55m
2026-06-21 ID424A71 - Jun 21, 16:19 UTCJun 22, 16:14 UTC23h 55m
2026-06-21 ID424A71 - Jun 21, 14:19 UTCJun 22, 14:14 UTC23h 55m
2026-06-21 ID424A71 - Jun 21, 12:19 UTCJun 22, 12:15 UTC23h 55m
2026-06-21 ID424A71 - Jun 21, 10:19 UTCJun 22, 10:15 UTC23h 55m
2026-06-21 ID424A71 - Jun 21, 08:20 UTCJun 22, 08:15 UTC23h 55m
2026-06-21 ID424A71 - Jun 21, 06:19 UTCJun 22, 06:15 UTC23h 55m
2026-06-21 ID424A71 - Jun 21, 04:20 UTCJun 22, 04:15 UTC23h 55m
2026-06-21 ID424A71 - Jun 21, 02:20 UTCJun 22, 02:14 UTC23h 55m
2026-06-21 ID424A71 - Jun 21, 00:19 UTCJun 22, 00:14 UTC23h 55m
2026-06-20 ID424A71 - Jun 20, 22:20 UTCJun 21, 22:15 UTC23h 55m
2026-06-20 ID424A71 - Jun 20, 16:19 UTCJun 21, 16:14 UTC23h 55m
2026-06-20 ID424A71 - Jun 20, 12:19 UTCJun 21, 12:14 UTC23h 55m
2026-06-20 ID424A71 - Jun 20, 10:20 UTCJun 21, 10:14 UTC23h 55m
2026-06-20 ID424A71 - Jun 20, 08:19 UTCJun 21, 08:15 UTC23h 55m
2026-06-20 ID424A71 - Jun 20, 04:20 UTCJun 21, 04:14 UTC23h 55m
2026-06-19 ID424A71 - Jun 19, 22:19 UTCJun 20, 22:14 UTC23h 55m
2026-06-19 ID424A71 - Jun 19, 18:20 UTCJun 20, 18:14 UTC23h 55m
2026-06-19 ID424A71 - Jun 19, 14:19 UTCJun 20, 14:14 UTC23h 55m
2026-06-19 ID424A71 - Jun 19, 12:19 UTCJun 20, 12:14 UTC23h 55m
2026-06-19 ID424A71 - Jun 19, 11:54 UTCJun 20, 10:15 UTC22h 20m
2026-06-07 ID424A71 - Jun 7, 22:20 UTCJun 8, 16:25 UTC18h 5m
2026-06-07 ID424A71 - Jun 7, 20:20 UTCJun 8, 16:25 UTC20h 5m
2026-06-07 ID424A71 - Jun 7, 18:20 UTCJun 8, 16:25 UTC22h 5m
2026-06-07 ID424A71 - Jun 7, 16:20 UTCJun 8, 16:15 UTC23h 55m
2026-06-07 ID424A71 - Jun 7, 14:20 UTCJun 8, 14:15 UTC23h 55m
2026-06-07 ID424A71 - Jun 7, 12:20 UTCJun 8, 12:15 UTC23h 55m
2026-06-07 ID424A71 - Jun 7, 10:20 UTCJun 8, 10:15 UTC23h 55m
2026-06-07 ID424A71 - Jun 7, 08:20 UTCJun 8, 08:15 UTC23h 55m
2026-06-07 ID424A71 - Jun 7, 06:20 UTCJun 8, 06:15 UTC23h 55m
2026-06-07 ID424A71 - Jun 7, 02:19 UTCJun 8, 02:15 UTC23h 55m
2026-06-07 ID424A71 - Jun 7, 00:19 UTCJun 8, 00:15 UTC23h 55m

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 TWR page for operator, model, and routing details .

Mode-S 424A71 frequently asked

What is Mode-S code 424A71?
424A71 is an ICAO 24-bit transponder address. Allocated to United Kingdom. Assigned to TWR.
Where is Mode-S 424A71 registered?
Mode-S code 424A71 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 424A71 broadcasting right now?
No active broadcast right now. Last signal was 23d ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 424A71, octal 20445161, decimal 4,344,433.
What flights does 424A71 operate?
Mode-S 424A71 has broadcast 1 distinct callsign, including ID424A71.