Apparatus

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sensors Mode-S transponder

781621

ICAO 24-bit transponder address · allocated to China

Currently assigned to B-306K · AIRBUS A-321neo

Hex
781621
Octal
36013041
Decimal
7,869,985
Country
CN
Tail
B-306K
Type
A21N
No current signal · last broadcast 2d ago
Flights observed
86
Distinct callsigns
20
Country
CN
Last broadcast
2d ago

Last known position

Most recent position reported by Mode-S 781621.

Country allocation

The ICAO 24-bit address 781621 falls within the block assigned to China (CN) by ICAO Annex 10, Volume III. Every aircraft registered in China 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
CSN623 - 14 2026-07-15
CSN624 - 10 2026-06-28
CSN6610 - 7 2026-07-14
CSN6545 - 6 2026-06-23
CSN6609 - 5 2026-07-14
CSN6553 - 5 2026-07-16
CSN8460 China Southern Airlines 4 2026-06-04
CSN6180 - 4 2026-07-14
CSN6146 - 4 2026-07-05
CSN8459 China Southern Airlines 3 2026-05-26
CSN6405 China Southern Airlines 3 2026-05-06
CSN6852 China Southern Airlines 2 2026-06-10
CSN6851 China Southern Airlines 2 2026-05-19
CSN6377 China Southern Airlines 2 2026-05-18
CSN6168 - 2 2026-06-25
CSN3605 China Southern Airlines 2 2026-06-09
CSN8531 China Southern Airlines 1 2026-05-29
CSN8256 China Southern Airlines 1 2026-06-12
CSN6541 - 1 2026-06-20
CSN6475 - 1 2026-07-13

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-16 CSN6553 - Jul 16, 04:30 UTCJul 16, 14:20 UTC9h 50m
2026-07-15 CSN623 - Jul 15, 10:00 UTCJul 16, 02:20 UTC16h 20m
2026-07-15 CSN623 - Jul 15, 02:30 UTCJul 16, 02:15 UTC23h 45m
2026-07-15 CSN6553 - Jul 15, 01:45 UTCJul 15, 14:35 UTC12h 50m
2026-07-14 CSN6553 - Jul 14, 11:30 UTCJul 15, 10:15 UTC22h 44m
2026-07-14 CSN6610 - Jul 14, 09:10 UTCJul 14, 09:20 UTC10m
2026-07-14 CSN6609 - Jul 14, 04:35 UTCJul 14, 04:45 UTC10m
2026-07-14 CSN6180 - Jul 14, 00:55 UTCJul 14, 01:05 UTC10m
2026-07-13 CSN6475 - Jul 13, 14:25 UTCJul 13, 14:35 UTC10m
2026-07-12 CSN6610 - Jul 12, 11:25 UTCJul 12, 11:45 UTC20m
2026-07-12 CSN6610 - Jul 12, 09:05 UTCJul 12, 09:15 UTC10m
2026-07-12 CSN6609 - Jul 12, 07:25 UTCJul 12, 07:45 UTC20m
2026-07-12 CSN6609 - Jul 12, 04:50 UTCJul 12, 05:01 UTC10m
2026-07-11 CSN6610 - Jul 11, 09:15 UTCJul 11, 09:25 UTC10m
2026-07-11 CSN6609 - Jul 11, 04:45 UTCJul 11, 04:55 UTC10m
2026-07-11 CSN6180 - Jul 11, 00:45 UTCJul 11, 00:55 UTC10m
2026-07-08 CSN6553 - Jul 8, 01:55 UTCJul 8, 10:20 UTC8h 25m
2026-07-05 CSN6146 - Jul 5, 03:55 UTCJul 5, 08:50 UTC4h 55m
2026-07-04 CSN6146 - Jul 4, 03:50 UTCJul 4, 04:00 UTC10m
2026-07-03 CSN6146 - Jul 3, 03:45 UTCJul 3, 10:25 UTC6h 40m
2026-07-03 CSN6145 - Jul 3, 01:35 UTCJul 3, 01:45 UTC10m
2026-07-02 CSN6610 - Jul 2, 13:10 UTCJul 2, 13:25 UTC15m
2026-07-02 CSN6610 - Jul 2, 10:50 UTCJul 2, 11:00 UTC10m
2026-07-02 CSN6180 - Jul 2, 01:55 UTCJul 2, 02:05 UTC10m
2026-07-01 CSN6342 - Jul 1, 01:00 UTCJul 1, 09:35 UTC8h 35m
2026-06-29 CSN6553 - Jun 29, 09:40 UTCJun 29, 10:24 UTC45m
2026-06-28 CSN624 - Jun 28, 04:44 UTCJun 28, 10:10 UTC5h 25m
2026-06-27 CSN623 - Jun 27, 11:04 UTCJun 28, 02:25 UTC15h 20m
2026-06-27 CSN623 - Jun 27, 02:29 UTCJun 28, 02:14 UTC23h 45m
2026-06-26 - - Jun 26, 10:05 UTCJun 27, 02:39 UTC16h 35m
2026-06-25 CSN6168 - Jun 25, 12:50 UTCJun 26, 10:05 UTC21h 15m
2026-06-25 CSN624 - Jun 25, 04:40 UTCJun 25, 05:15 UTC35m
2026-06-25 CSN623 - Jun 25, 01:44 UTCJun 25, 02:25 UTC40m
2026-06-24 CSN623 - Jun 24, 02:24 UTCJun 25, 02:14 UTC23h 50m
2026-06-23 CSN6545 - Jun 23, 00:15 UTCJun 23, 09:24 UTC9h 10m
2026-06-21 CSN624 - Jun 21, 04:39 UTCJun 21, 09:55 UTC5h 15m
2026-06-20 CSN623 - Jun 20, 09:59 UTCJun 21, 02:24 UTC16h 25m
2026-06-20 CSN6541 - Jun 20, 02:04 UTCJun 20, 09:59 UTC7h 55m
2026-06-15 CSN6545 - Jun 15, 14:20 UTCJun 16, 09:10 UTC18h 50m
2026-06-15 CSN6545 - Jun 15, 00:40 UTCJun 16, 00:10 UTC23h 30m
2026-06-13 CSN6545 CGQ → HGH Jun 13, 09:35 UTCJun 14, 00:50 UTC15h 15m
2026-06-12 CSN8256 CKG → CGQ Jun 12, 13:20 UTCJun 13, 09:35 UTC20h 14m
2026-06-10 CSN6852 CAN → CGQ Jun 10, 14:40 UTCJun 11, 07:45 UTC17h 5m
2026-06-09 CSN3605 CGQ → CAN Jun 9, 03:00 UTCJun 9, 03:20 UTC20m
2026-06-07 CSN6168 PKX → CGQ Jun 7, 12:30 UTCJun 8, 01:00 UTC12h 30m
2026-06-07 CSN624 NRT → CGQ Jun 7, 04:40 UTCJun 7, 05:15 UTC35m
2026-06-06 CSN623 CGQ → NRT Jun 6, 12:20 UTCJun 7, 02:14 UTC13h 55m
2026-06-04 CSN8460 CAN → CGQ Jun 4, 10:55 UTCJun 4, 11:15 UTC20m
2026-05-30 CSN8460 CAN → CGQ May 30, 10:55 UTCMay 30, 11:10 UTC15m
2026-05-29 CSN8531 CAN → KHN May 29, 08:40 UTCMay 29, 09:00 UTC20m

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 B-306K page for operator, model, and routing details .

Mode-S 781621 frequently asked

What is Mode-S code 781621?
781621 is an ICAO 24-bit transponder address. Allocated to China. Assigned to B-306K.
Where is Mode-S 781621 registered?
Mode-S code 781621 is allocated to China (CN). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 781621 broadcasting right now?
No active broadcast right now. Last signal was 2d ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 781621, octal 36013041, decimal 7,869,985.
What flights does 781621 operate?
Mode-S 781621 has broadcast 20 distinct callsigns, including CSN623, CSN624, CSN6610, CSN6545, CSN6609.