Apparatus

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sensors Mode-S transponder

71C399

ICAO 24-bit transponder address · allocated to Korea, South

Currently assigned to HL8399 · AIRBUS A-321neo

Hex
71C399
Octal
34341631
Decimal
7,455,641
Country
KR
Tail
HL8399
Type
A21N
No current signal · last broadcast 1h ago
Flights observed
311
Distinct callsigns
20
Country
KR
Last broadcast
1h ago

Last known position

Most recent position reported by Mode-S 71C399.

Country allocation

The ICAO 24-bit address 71C399 falls within the block assigned to Korea, South (KR) by ICAO Annex 10, Volume III. Every aircraft registered in Korea, South 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
AAR744 - 42 2026-07-13
AAR743 - 39 2026-07-13
AAR722 - 27 2026-06-16
AAR721 - 27 2026-06-16
AAR755 Asiana Airlines 22 2026-05-31
AAR735 - 19 2026-07-05
AAR736 - 15 2026-07-06
AAR756 Asiana Airlines 8 2026-05-30
AAR118 - 8 2026-07-01
AAR117 - 8 2026-07-01
AAR371 - 7 2026-07-14
AAR372 - 5 2026-07-14
AAR173 Asiana Airlines 5 2026-05-26
AAR745 - 4 2026-07-13
AAR174 Asiana Airlines 4 2026-05-26
AAR152 - 4 2026-06-17
AAR746 - 3 2026-07-13
AAR730 - 3 2026-07-10
AAR322 Asiana Airlines 3 2026-05-08
AAR151 - 3 2026-06-17

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-14 AAR372 - Jul 14, 08:50 UTCJul 14, 09:30 UTC40m
2026-07-14 AAR371 - Jul 14, 01:30 UTCJul 14, 02:10 UTC40m
2026-07-13 AAR746 HKG → ICN Jul 13, 18:10 UTCJul 13, 21:25 UTC3h 15m
2026-07-13 AAR745 ICN → HKG Jul 13, 12:15 UTCJul 13, 15:20 UTC3h 5m
2026-07-13 AAR744 - Jul 13, 07:50 UTCJul 13, 10:25 UTC2h 35m
2026-07-13 AAR744 - Jul 13, 05:15 UTCJul 13, 05:31 UTC15m
2026-07-13 AAR743 - Jul 13, 03:30 UTCJul 13, 03:45 UTC15m
2026-07-12 AAR743 - Jul 12, 22:40 UTCJul 13, 01:15 UTC2h 35m
2026-07-12 AAR744 - Jul 12, 07:45 UTCJul 12, 10:20 UTC2h 35m
2026-07-12 AAR744 - Jul 12, 05:15 UTCJul 12, 05:30 UTC15m
2026-07-12 AAR743 - Jul 12, 03:20 UTCJul 12, 03:40 UTC20m
2026-07-11 AAR743 - Jul 11, 22:30 UTCJul 12, 00:55 UTC2h 25m
2026-07-11 AAR744 - Jul 11, 11:10 UTCJul 11, 11:35 UTC25m
2026-07-11 AAR744 - Jul 11, 06:10 UTCJul 11, 07:50 UTC1h 40m
2026-07-10 AAR743 - Jul 10, 23:25 UTCJul 11, 04:25 UTC5h 0m
2026-07-10 AAR354 - Jul 10, 21:20 UTCJul 10, 21:35 UTC15m
2026-07-10 AAR353 - Jul 10, 13:20 UTCJul 10, 13:45 UTC25m
2026-07-10 AAR730 - Jul 10, 10:20 UTCJul 10, 11:00 UTC40m
2026-07-10 AAR730 - Jul 10, 06:55 UTCJul 10, 07:05 UTC10m
2026-07-10 AAR729 - Jul 10, 00:50 UTCJul 10, 01:40 UTC50m
2026-07-09 AAR746 HKG → ICN Jul 9, 18:10 UTCJul 9, 21:20 UTC3h 10m
2026-07-09 AAR745 ICN → HKG Jul 9, 12:30 UTCJul 9, 15:35 UTC3h 5m
2026-07-09 AAR744 - Jul 9, 05:45 UTCJul 9, 11:00 UTC5h 15m
2026-07-09 AAR743 - Jul 9, 00:25 UTCJul 9, 04:10 UTC3h 45m
2026-07-08 AAR743 - Jul 8, 22:45 UTCJul 8, 23:25 UTC40m
2026-07-08 AAR113 KIX → ICN Jul 8, 11:10 UTCJul 8, 12:40 UTC1h 30m
2026-07-08 AAR114 ICN → KIX Jul 8, 08:25 UTCJul 8, 09:50 UTC1h 25m
2026-07-08 AAR304 - Jul 8, 05:15 UTCJul 8, 05:35 UTC20m
2026-07-08 AAR303 - Jul 8, 00:45 UTCJul 8, 01:05 UTC20m
2026-07-07 AAR334 - Jul 7, 11:40 UTCJul 7, 12:00 UTC20m
2026-07-07 AAR334 - Jul 7, 10:40 UTCJul 7, 10:50 UTC10m
2026-07-07 AAR333 - Jul 7, 04:30 UTCJul 7, 04:50 UTC20m
2026-07-06 AAR736 ICN → ICN Jul 6, 12:20 UTCJul 6, 23:40 UTC11h 20m
2026-07-06 AAR372 - Jul 6, 09:45 UTCJul 6, 10:25 UTC40m
2026-07-06 AAR371 - Jul 6, 02:10 UTCJul 6, 02:50 UTC40m
2026-07-05 AAR735 - Jul 5, 10:50 UTCJul 5, 22:50 UTC12h 0m
2026-07-05 AAR370 - Jul 5, 07:10 UTCJul 5, 07:55 UTC45m
2026-07-05 AAR369 - Jul 5, 00:20 UTCJul 5, 00:55 UTC35m
2026-07-04 AAR744 - Jul 4, 05:15 UTCJul 4, 10:15 UTC5h 0m
2026-07-03 AAR743 ICN → BKK Jul 3, 22:25 UTCJul 4, 03:50 UTC5h 25m
2026-07-03 AAR744 - Jul 3, 10:10 UTCJul 3, 10:45 UTC35m
2026-07-03 AAR744 - Jul 3, 05:30 UTCJul 3, 07:10 UTC1h 40m
2026-07-02 AAR743 ICN → BKK Jul 2, 22:30 UTCJul 3, 03:50 UTC5h 20m
2026-07-02 AAR744 - Jul 2, 05:35 UTCJul 2, 11:00 UTC5h 25m
2026-07-01 AAR743 ICN → BKK Jul 1, 22:45 UTCJul 2, 04:00 UTC5h 15m
2026-07-01 AAR117 KIX → ICN Jul 1, 15:25 UTCJul 1, 16:40 UTC1h 15m
2026-07-01 AAR118 ICN → KIX Jul 1, 12:30 UTCJul 1, 13:50 UTC1h 20m
2026-07-01 AAR730 - Jul 1, 07:05 UTCJul 1, 11:00 UTC3h 55m
2026-07-01 AAR729 - Jul 1, 01:00 UTCJul 1, 05:05 UTC4h 5m
2026-06-30 AAR746 - Jun 30, 18:00 UTCJun 30, 21:05 UTC3h 5m

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 HL8399 page for operator, model, and routing details .

Mode-S 71C399 frequently asked

What is Mode-S code 71C399?
71C399 is an ICAO 24-bit transponder address. Allocated to Korea, South. Assigned to HL8399.
Where is Mode-S 71C399 registered?
Mode-S code 71C399 is allocated to Korea, South (KR). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 71C399 broadcasting right now?
No active broadcast right now. Last signal was 1h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 71C399, octal 34341631, decimal 7,455,641.
What flights does 71C399 operate?
Mode-S 71C399 has broadcast 20 distinct callsigns, including AAR744, AAR743, AAR722, AAR721, AAR755.