Apparatus

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sensors Mode-S transponder

406B1B

ICAO 24-bit transponder address · allocated to United Kingdom

Currently assigned to G-JMCS · BOEING 737-400

Hex
406B1B
Octal
20065433
Decimal
4,221,723
Country
GB
Tail
G-JMCS
Type
B734
No current signal · last broadcast 23h ago
Flights observed
91
Distinct callsigns
17
Country
GB
Last broadcast
23h ago

Last known position

Most recent position reported by Mode-S 406B1B.

Country allocation

The ICAO 24-bit address 406B1B 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 17 distinct

Callsign Airline Flights Last seen
NPT5U - 18 2026-07-03
NPT5D - 16 2026-07-03
NPT2L - 15 2026-06-30
NPT2R - 12 2026-06-16
NPT3EA - 7 2026-07-16
NPT2EA - 7 2026-07-17
NPT3E - 4 2026-06-30
NPT1B - 2 2026-06-25
N3E - 2 2026-04-18
NPT734P - 1 2026-06-24
NPT346F - 1 2026-06-27
NPT346 - 1 2026-06-27
NPT328F - 1 2026-07-14
NPT327F - 1 2026-07-14
NPT327 - 1 2026-07-14
NPT1A - 1 2026-04-15
347F - 1 2026-06-27

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-17 NPT2EA - Jul 17, 01:55 UTCJul 17, 02:45 UTC50m
2026-07-16 NPT3EA - Jul 16, 21:55 UTCJul 16, 22:49 UTC55m
2026-07-16 NPT2EA - Jul 16, 01:50 UTCJul 16, 02:45 UTC55m
2026-07-15 NPT3EA EMA → LGG Jul 15, 22:05 UTCJul 15, 23:00 UTC55m
2026-07-15 NPT2EA - Jul 15, 01:50 UTCJul 15, 02:45 UTC55m
2026-07-14 NPT3EA EMA → LGG Jul 14, 21:50 UTCJul 14, 22:45 UTC54m
2026-07-14 NPT328F - Jul 14, 12:20 UTCJul 14, 12:50 UTC30m
2026-07-14 NPT327 - Jul 14, 10:30 UTCJul 14, 11:15 UTC45m
2026-07-14 NPT327F EMA → LGG Jul 14, 08:00 UTCJul 14, 09:05 UTC1h 5m
2026-07-14 NPT2EA - Jul 14, 01:50 UTCJul 14, 02:40 UTC50m
2026-07-13 NPT3EA - Jul 13, 21:50 UTCJul 13, 22:45 UTC55m
2026-07-09 NPT2EA - Jul 9, 01:55 UTCJul 9, 02:45 UTC50m
2026-07-08 NPT3EA EMA → LGG Jul 8, 21:35 UTCJul 8, 22:30 UTC55m
2026-07-08 NPT2EA - Jul 8, 02:10 UTCJul 8, 03:05 UTC55m
2026-07-07 NPT3EA - Jul 7, 21:40 UTCJul 7, 22:30 UTC50m
2026-07-07 NPT2EA - Jul 7, 01:50 UTCJul 7, 02:45 UTC55m
2026-07-06 NPT3EA - Jul 6, 21:45 UTCJul 6, 22:40 UTC55m
2026-07-03 NPT5D EDI → EMA Jul 3, 22:55 UTCJul 3, 23:35 UTC40m
2026-07-03 NPT5U EMA → EDI Jul 3, 01:25 UTCJul 3, 02:10 UTC45m
2026-06-30 NPT3E - Jun 30, 22:50 UTCJun 30, 23:30 UTC40m
2026-06-30 NPT2L EMA → BFS Jun 30, 00:30 UTCJun 30, 01:09 UTC40m
2026-06-27 347F - Jun 27, 12:29 UTCJun 27, 13:20 UTC50m
2026-06-27 NPT346 - Jun 27, 10:40 UTCJun 27, 11:30 UTC50m
2026-06-27 NPT346F EMA → BOH Jun 27, 08:29 UTCJun 27, 09:04 UTC35m
2026-06-25 NPT3E - Jun 25, 22:54 UTCJun 25, 23:34 UTC40m
2026-06-25 NPT1B EMA → BFS Jun 25, 01:24 UTCJun 25, 02:05 UTC40m
2026-06-24 NPT734P EDI → EMA Jun 24, 23:24 UTCJun 25, 00:09 UTC45m
2026-06-20 NPT5U EMA → EDI Jun 20, 01:14 UTCJun 20, 01:55 UTC40m
2026-06-19 NPT5D EDI → EMA Jun 19, 22:55 UTCJun 19, 23:39 UTC45m
2026-06-19 NPT5U EMA → EDI Jun 19, 01:24 UTCJun 19, 02:04 UTC40m
2026-06-18 NPT5D EDI → EMA Jun 18, 22:55 UTCJun 18, 23:35 UTC40m
2026-06-18 NPT5U EMA → EDI Jun 18, 01:15 UTCJun 18, 01:55 UTC40m
2026-06-17 NPT3E - Jun 17, 23:00 UTCJun 17, 23:40 UTC40m
2026-06-17 NPT2L EMA → BFS Jun 17, 01:35 UTCJun 17, 02:15 UTC40m
2026-06-16 NPT2R BFS → EMA Jun 16, 23:40 UTCJun 17, 00:25 UTC45m
2026-06-16 NPT2L EMA → BFS Jun 16, 01:00 UTCJun 16, 01:40 UTC40m
2026-06-12 NPT5D EDI → EMA Jun 12, 22:55 UTCJun 12, 23:30 UTC35m
2026-06-12 NPT5U EMA → EDI Jun 12, 01:10 UTCJun 12, 02:00 UTC50m
2026-06-11 NPT5D EDI → EMA Jun 11, 23:00 UTCJun 11, 23:35 UTC35m
2026-06-11 NPT5U EMA → EDI Jun 11, 01:20 UTCJun 11, 02:10 UTC50m
2026-06-10 NPT5D EDI → EMA Jun 10, 22:45 UTCJun 10, 23:25 UTC40m
2026-06-10 NPT5U EMA → EDI Jun 10, 01:20 UTCJun 10, 02:05 UTC45m
2026-06-09 NPT5D EDI → EMA Jun 9, 23:00 UTCJun 9, 23:45 UTC45m
2026-06-09 NPT5U EMA → EDI Jun 9, 01:35 UTCJun 9, 02:15 UTC40m
2026-06-05 NPT5D EDI → EMA Jun 5, 22:55 UTCJun 5, 23:40 UTC45m
2026-06-05 NPT5U EMA → EDI Jun 5, 01:30 UTCJun 5, 02:10 UTC40m
2026-06-04 NPT5D EDI → EMA Jun 4, 22:45 UTCJun 4, 23:30 UTC45m
2026-06-04 NPT5U EMA → EDI Jun 4, 01:30 UTCJun 4, 02:10 UTC40m
2026-06-03 NPT5D EDI → EMA Jun 3, 23:20 UTCJun 4, 00:05 UTC45m
2026-06-03 NPT5U EMA → EDI Jun 3, 01:40 UTCJun 3, 02:25 UTC45m

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-JMCS page for operator, model, and routing details .

Mode-S 406B1B frequently asked

What is Mode-S code 406B1B?
406B1B is an ICAO 24-bit transponder address. Allocated to United Kingdom. Assigned to G-JMCS.
Where is Mode-S 406B1B registered?
Mode-S code 406B1B 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 406B1B broadcasting right now?
No active broadcast right now. Last signal was 23h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 406B1B, octal 20065433, decimal 4,221,723.
What flights does 406B1B operate?
Mode-S 406B1B has broadcast 17 distinct callsigns, including NPT5U, NPT5D, NPT2L, NPT2R, NPT3EA.