Apparatus

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sensors Mode-S transponder

851C20

ICAO 24-bit transponder address · allocated to Japan

Currently assigned to JA343J · BOEING 737-800

Hex
851C20
Octal
41216040
Decimal
8,723,488
Country
JP
Tail
JA343J
Type
B738
No current signal · last broadcast 9h ago
Flights observed
544
Distinct callsigns
20
Country
JP
Last broadcast
9h ago

Last known position

Most recent position reported by Mode-S 851C20.

Country allocation

The ICAO 24-bit address 851C20 falls within the block assigned to Japan (JP) by ICAO Annex 10, Volume III. Every aircraft registered in Japan 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 20 distinct

Callsign Airline Flights Last seen
JAL214 - 11 2026-06-23
JAL509 - 8 2026-06-20
JAL461 Japan Airlines 8 2026-06-07
JAL2004 - 8 2026-06-20
JAL151 - 8 2026-06-19
JAL140 - 8 2026-06-19
JAL462 Japan Airlines 7 2026-06-07
JAL432 Japan Airlines 7 2026-05-26
JAL2506 - 7 2026-06-17
JAL228 - 7 2026-06-17
JAL215 - 7 2026-06-23
JAL2009 - 7 2026-06-17
JAL641 - 6 2026-07-01
JAL431 Japan Airlines 6 2026-05-25
JAL671 - 5 2026-06-23
JAL662 - 5 2026-06-23
JAL624 Japan Airlines 5 2026-06-07
JAL623 Japan Airlines 5 2026-06-06
JAL609 - 5 2026-07-13
JAL562 - 5 2026-07-14

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-14 JAL498 HND → HND Jul 14, 08:15 UTCJul 14, 11:30 UTC3h 15m
2026-07-14 JAL670 - Jul 14, 05:45 UTCJul 14, 07:00 UTC1h 15m
2026-07-14 JAL665 - Jul 14, 03:30 UTCJul 14, 04:30 UTC1h 0m
2026-07-14 JAL562 - Jul 14, 00:45 UTCJul 14, 02:20 UTC1h 35m
2026-07-13 JAL565 - Jul 13, 22:25 UTCJul 13, 23:55 UTC1h 30m
2026-07-13 JL616 - Jul 13, 12:20 UTCJul 13, 13:50 UTC1h 30m
2026-07-13 JAL613 - Jul 13, 09:25 UTCJul 13, 10:45 UTC1h 20m
2026-07-13 JAL612 - Jul 13, 06:15 UTCJul 13, 08:05 UTC1h 50m
2026-07-13 JAL609 - Jul 13, 03:50 UTCJul 13, 05:10 UTC1h 20m
2026-07-13 JAL552 AKJ → HND Jul 13, 01:20 UTCJul 13, 02:35 UTC1h 15m
2026-07-12 JAL551 - Jul 12, 23:05 UTCJul 13, 00:20 UTC1h 15m
2026-07-12 JAL486 - Jul 12, 11:55 UTCJul 12, 13:10 UTC1h 15m
2026-07-12 JAL485 - Jul 12, 10:10 UTCJul 12, 11:01 UTC50m
2026-07-12 JAL262 - Jul 12, 07:40 UTCJul 12, 09:00 UTC1h 20m
2026-07-12 JAL263 HND → HIJ Jul 12, 05:40 UTCJul 12, 06:40 UTC1h 0m
2026-07-12 JAL668 - Jul 12, 03:15 UTCJul 12, 04:20 UTC1h 5m
2026-07-12 JAL663 - Jul 12, 01:05 UTCJul 12, 02:05 UTC1h 0m
2026-07-11 JAL202 - Jul 11, 23:00 UTCJul 11, 23:45 UTC45m
2026-07-11 JAL3118 - Jul 11, 11:55 UTCJul 11, 13:10 UTC1h 15m
2026-07-11 JAL3117 - Jul 11, 09:25 UTCJul 11, 10:50 UTC1h 25m
2026-07-11 JAL3114 - Jul 11, 06:45 UTCJul 11, 08:01 UTC1h 15m
2026-07-11 JAL3107 - Jul 11, 04:05 UTCJul 11, 05:35 UTC1h 30m
2026-07-11 JAL3106 - Jul 11, 01:35 UTCJul 11, 02:50 UTC1h 15m
2026-07-10 JAL2001 - Jul 10, 22:55 UTCJul 11, 00:30 UTC1h 35m
2026-07-10 JAL3009 - Jul 10, 09:55 UTCJul 10, 10:50 UTC55m
2026-07-10 JAL3006 - Jul 10, 05:45 UTCJul 10, 07:00 UTC1h 15m
2026-07-10 JAL2465 - Jul 10, 00:55 UTCJul 10, 04:40 UTC3h 45m
2026-07-09 JAL2016 - Jul 9, 09:20 UTCJul 9, 10:55 UTC1h 35m
2026-07-09 JAL2505 - Jul 9, 06:35 UTCJul 9, 08:10 UTC1h 35m
2026-07-09 JAL2504 - Jul 9, 03:05 UTCJul 9, 05:00 UTC1h 55m
2026-07-09 JAL2501 - Jul 9, 00:30 UTCJul 9, 02:00 UTC1h 30m
2026-07-08 JAL221 HND → KIX Jul 8, 22:35 UTCJul 8, 23:30 UTC55m
2026-07-08 JAL674 - Jul 8, 10:15 UTCJul 8, 11:30 UTC1h 15m
2026-07-08 JAL669 - Jul 8, 08:05 UTCJul 8, 09:05 UTC1h 0m
2026-07-08 JAL436 - Jul 8, 05:30 UTCJul 8, 06:45 UTC1h 15m
2026-07-08 JAL435 - Jul 8, 03:30 UTCJul 8, 04:25 UTC55m
2026-07-08 JAL476 - Jul 8, 00:50 UTCJul 8, 01:50 UTC1h 0m
2026-07-07 JAL475 - Jul 7, 23:05 UTCJul 7, 23:55 UTC50m
2026-07-07 JAL486 - Jul 7, 11:45 UTCJul 7, 12:40 UTC55m
2026-07-07 JAL485 - Jul 7, 10:00 UTCJul 7, 10:50 UTC50m
2026-07-07 JAL262 - Jul 7, 07:35 UTCJul 7, 08:35 UTC1h 0m
2026-07-07 JAL263 - Jul 7, 05:40 UTCJul 7, 06:45 UTC1h 5m
2026-07-05 JAL558 - Jul 5, 11:30 UTCJul 5, 12:50 UTC1h 20m
2026-07-05 JAL557 - Jul 5, 09:10 UTCJul 5, 10:25 UTC1h 15m
2026-07-05 JAL146 - Jul 5, 06:30 UTCJul 5, 07:25 UTC55m
2026-07-05 JAL145 - Jul 5, 04:30 UTCJul 5, 05:20 UTC50m
2026-07-05 JAL374 - Jul 5, 01:55 UTCJul 5, 03:10 UTC1h 15m
2026-07-04 JAL373C - Jul 4, 23:30 UTCJul 5, 00:40 UTC1h 10m
2026-07-03 JAL616 NGS → HND Jul 3, 11:30 UTCJul 3, 12:55 UTC1h 25m
2026-07-03 JAL613 - Jul 3, 09:00 UTCJul 3, 10:30 UTC1h 30m

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 JA343J page for operator, model, and routing details .

Mode-S 851C20 frequently asked

What is Mode-S code 851C20?
851C20 is an ICAO 24-bit transponder address. Allocated to Japan. Assigned to JA343J.
Where is Mode-S 851C20 registered?
Mode-S code 851C20 is allocated to Japan (JP). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 851C20 broadcasting right now?
No active broadcast right now. Last signal was 9h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 851C20, octal 41216040, decimal 8,723,488.
What flights does 851C20 operate?
Mode-S 851C20 has broadcast 20 distinct callsigns, including JAL214, JAL509, JAL461, JAL2004, JAL151.