Apparatus

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sensors Mode-S transponder

8681B3

ICAO 24-bit transponder address · allocated to Japan

Currently assigned to JA73NM · BOEING 737-800

Hex
8681B3
Octal
41500663
Decimal
8,815,027
Country
JP
Tail
JA73NM
Type
B738
No current signal · last broadcast Jul 26, 12:05 UTC
Flights observed
541
Distinct callsigns
20
Country
JP
Last broadcast
Jul 26, 12:05 UTC

Last known position

Most recent position reported by Mode-S 8681B3.

Country allocation

The ICAO 24-bit address 8681B3 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
SKY718 - 8 2026-07-03
SKY727 - 7 2026-07-12
SKY593 - 7 2026-07-19
SKY522 Skymark Airlines 7 2026-07-13
SKY836 - 6 2026-07-16
SKY831 - 6 2026-07-16
SKY768 - 6 2026-07-12
SKY713 - 6 2026-07-02
SKY599 Skymark Airlines 6 2026-07-23
SKY521 - 6 2026-07-13
SKY519 Skymark Airlines 6 2026-07-23
SKY511 - 6 2026-07-02
SKY501 Skymark Airlines 6 2026-07-20
SKY183 - 6 2026-07-22
SKY182 - 6 2026-07-15
SKY177 - 6 2026-07-03
SKY157 - 6 2026-06-29
SKY156 - 6 2026-06-29
SKY142 Skymark Airlines 6 2026-07-23
SKY141 Skymark Airlines 6 2026-07-23

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 SKY116 UKB → HND Jul 26, 11:10 UTCJul 26, 12:05 UTC55m
2026-07-26 SKY594 OKA → UKB Jul 26, 07:50 UTCJul 26, 09:35 UTC1h 45m
2026-07-26 SKY517 HND → OKA Jul 26, 04:40 UTCJul 26, 06:35 UTC1h 56m
2026-07-26 SKY106 UKB → HND Jul 26, 02:05 UTCJul 26, 03:05 UTC1h 0m
2026-07-26 SKY103 HND → UKB Jul 26, 00:15 UTCJul 26, 01:05 UTC50m
2026-07-25 SKY100 UKB → HND Jul 25, 22:25 UTCJul 25, 23:25 UTC1h 0m
2026-07-25 SKY178 - Jul 25, 12:00 UTCJul 25, 13:35 UTC1h 35m
2026-07-25 SKY795 IBR → CTS Jul 25, 09:45 UTCJul 25, 11:05 UTC1h 20m
2026-07-25 SKY532 OKA → IBR Jul 25, 06:45 UTCJul 25, 08:55 UTC2h 10m
2026-07-25 SKY163 UKB → SHI Jul 25, 02:05 UTCJul 25, 03:40 UTC1h 35m
2026-07-25 SKY132 KOJ → UKB Jul 25, 00:25 UTCJul 25, 01:05 UTC40m
2026-07-24 SKY301 HND → KOJ Jul 24, 21:55 UTCJul 24, 23:00 UTC1h 5m
2026-07-24 SKY024 FUK → HND Jul 24, 11:45 UTCJul 24, 13:15 UTC1h 30m
2026-07-24 SKY023 HND → FUK Jul 24, 09:25 UTCJul 24, 10:30 UTC1h 5m
2026-07-24 SKY510 OKA → HND Jul 24, 00:00 UTCJul 24, 00:40 UTC40m
2026-07-23 SKY510 OKA → HND Jul 23, 22:30 UTCJul 23, 22:40 UTC10m
2026-07-23 SKY599 UKB → OKA Jul 23, 13:50 UTCJul 23, 14:05 UTC15m
2026-07-23 SKY599 UKB → OKA Jul 23, 12:30 UTCJul 23, 13:05 UTC35m
2026-07-23 SKY596 OKA → UKB Jul 23, 10:10 UTCJul 23, 11:40 UTC1h 30m
2026-07-23 SKY519 HND → OKA Jul 23, 08:55 UTCJul 23, 09:10 UTC15m
2026-07-23 SKY519 HND → OKA Jul 23, 07:05 UTCJul 23, 07:45 UTC40m
2026-07-23 SKY108 UKB → HND Jul 23, 04:15 UTCJul 23, 05:15 UTC1h 0m
2026-07-23 SKY142 NGS → UKB Jul 23, 02:30 UTCJul 23, 03:25 UTC55m
2026-07-23 SKY141 UKB → NGS Jul 23, 00:45 UTCJul 23, 01:35 UTC50m
2026-07-22 SKY183 - Jul 22, 22:45 UTCJul 22, 23:45 UTC1h 0m
2026-07-22 SKY186 - Jul 22, 11:10 UTCJul 22, 11:40 UTC30m
2026-07-22 SKY514 OKA → HND Jul 22, 02:10 UTCJul 22, 04:25 UTC2h 15m
2026-07-21 SKY553 NGO → OKA Jul 21, 23:10 UTCJul 22, 00:50 UTC1h 40m
2026-07-21 SKY309 HND → KOJ Jul 21, 10:25 UTCJul 21, 13:35 UTC3h 10m
2026-07-21 SKY018 - Jul 21, 08:00 UTCJul 21, 09:25 UTC1h 25m
2026-07-21 SKY015 HND → FUK Jul 21, 05:00 UTCJul 21, 06:05 UTC1h 5m
2026-07-21 SKY304 KOJ → HND Jul 21, 02:40 UTCJul 21, 03:50 UTC1h 10m
2026-07-21 SKY303 HND → KOJ Jul 21, 00:00 UTCJul 21, 01:05 UTC1h 5m
2026-07-20 SKY726 - Jul 20, 10:45 UTCJul 20, 12:00 UTC1h 15m
2026-07-20 SKY723 - Jul 20, 08:30 UTCJul 20, 09:40 UTC1h 10m
2026-07-20 SKY518 OKA → HND Jul 20, 04:45 UTCJul 20, 07:00 UTC2h 15m
2026-07-20 SKY501 FUK → OKA Jul 20, 00:25 UTCJul 20, 00:40 UTC15m
2026-07-19 SKY501 FUK → OKA Jul 19, 23:25 UTCJul 19, 23:40 UTC15m
2026-07-19 SKY508 OKA → FUK Jul 19, 11:40 UTCJul 19, 11:55 UTC15m
2026-07-19 SKY508 OKA → FUK Jul 19, 10:50 UTCJul 19, 11:00 UTC10m
2026-07-19 SKY509 - Jul 19, 09:35 UTCJul 19, 09:45 UTC10m
2026-07-19 SKY509 - Jul 19, 08:35 UTCJul 19, 08:50 UTC15m
2026-07-19 SKY506 - Jul 19, 06:15 UTCJul 19, 07:20 UTC1h 5m
2026-07-19 SKY593 - Jul 19, 04:25 UTCJul 19, 04:35 UTC10m
2026-07-19 SKY593 - Jul 19, 03:05 UTCJul 19, 03:40 UTC35m
2026-07-19 SKY153 - Jul 19, 01:05 UTCJul 19, 02:05 UTC1h 0m
2026-07-18 SKY152 - Jul 18, 22:55 UTCJul 18, 23:45 UTC50m
2026-07-18 SKY117 HND → UKB Jul 18, 11:25 UTCJul 18, 12:15 UTC50m
2026-07-18 SKY020 - Jul 18, 08:50 UTCJul 18, 10:15 UTC1h 25m
2026-07-18 SKY019 HND → FUK Jul 18, 06:25 UTCJul 18, 07:35 UTC1h 10m

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 JA73NM page for operator, model, and routing details .

Mode-S 8681B3 frequently asked

What is Mode-S code 8681B3?
8681B3 is an ICAO 24-bit transponder address. Allocated to Japan. Assigned to JA73NM.
Where is Mode-S 8681B3 registered?
Mode-S code 8681B3 is allocated to Japan (JP). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 8681B3 broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 12:05 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 8681B3, octal 41500663, decimal 8,815,027.
What flights does 8681B3 operate?
Mode-S 8681B3 has broadcast 20 distinct callsigns, including SKY718, SKY727, SKY593, SKY522, SKY836.