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
Broadcasting now · 39,000 ft
Flights observed
15
Distinct callsigns
10
Country
JP
Last broadcast
17h ago

Current position

851C20 is currently broadcasting. Map zoomed to live position.

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 10 distinct

Callsign Airline Flights Last seen
JAL3118 - 3 2026-04-13
JAL520 - 2 2026-04-14
JAL3515 - 2 2026-04-14
JAL3107 Japan Airlines 2 2026-04-13
JAL465 - 1 2026-04-14
JAL3117 - 1 2026-04-13
JAL3114 - 1 2026-04-13
JAL3106 - 1 2026-04-13
JAL3101 Japan Airlines 1 2026-04-13
JAL2001 Japan Airlines 1 2026-04-12

Recent flights last 15

DateFlightRouteTakeoffLandingDuration
2026-04-14 JAL465 - Apr 14, 11:00 UTCApr 14, 11:05 UTC5m
2026-04-14 JAL520 - Apr 14, 09:15 UTCApr 14, 10:00 UTC45m
2026-04-14 JAL520 - Apr 14, 08:35 UTCApr 14, 09:05 UTC30m
2026-04-14 JAL3515 - Apr 14, 07:10 UTCApr 14, 07:25 UTC15m
2026-04-14 JAL3515 - Apr 14, 05:40 UTCApr 14, 07:10 UTC1h 30m
2026-04-13 JAL3101 NGO → CTS Apr 13, 23:25 UTCApr 13, 23:40 UTC15m
2026-04-13 JAL3118 - Apr 13, 12:20 UTCApr 13, 12:35 UTC15m
2026-04-13 JAL3118 - Apr 13, 12:05 UTCApr 13, 12:35 UTC30m
2026-04-13 JAL3118 - Apr 13, 11:20 UTCApr 13, 12:15 UTC55m
2026-04-13 JAL3117 - Apr 13, 09:05 UTCApr 13, 10:25 UTC1h 20m
2026-04-13 JAL3114 - Apr 13, 06:25 UTCApr 13, 07:45 UTC1h 20m
2026-04-13 JAL3107 NGO → CTS Apr 13, 04:20 UTCApr 13, 05:15 UTC55m
2026-04-13 JAL3107 NGO → CTS Apr 13, 03:55 UTCApr 13, 04:15 UTC20m
2026-04-13 JAL3106 - Apr 13, 01:25 UTCApr 13, 02:45 UTC1h 20m
2026-04-12 JAL2001 ITM → CTS Apr 12, 23:55 UTCApr 13, 00:25 UTC30m

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?
Yes. Mode-S 851C20 is currently airborne.
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 10 distinct callsigns, including JAL3118, JAL520, JAL3515, JAL3107, JAL465.