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 Jul 25, 09:30 UTC
Flights observed
349
Distinct callsigns
20
Country
KR
Last broadcast
Jul 25, 09:30 UTC

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 Asiana Airlines 46 2026-07-23
AAR743 Asiana Airlines 43 2026-07-22
AAR722 Asiana Airlines 29 2026-07-21
AAR721 Asiana Airlines 29 2026-07-21
AAR755 - 23 2026-07-19
AAR735 Asiana Airlines 21 2026-07-24
AAR736 Asiana Airlines 17 2026-07-24
AAR371 Asiana Airlines 12 2026-07-24
AAR372 Asiana Airlines 11 2026-07-24
AAR756 Asiana Airlines 8 2026-05-30
AAR118 - 8 2026-07-01
AAR117 - 8 2026-07-01
AAR745 - 5 2026-07-15
AAR173 Asiana Airlines 5 2026-05-26
AAR746 - 4 2026-07-15
AAR322 Asiana Airlines 4 2026-07-23
AAR174 Asiana Airlines 4 2026-05-26
AAR152 - 4 2026-06-17
AAR730 - 3 2026-07-10
AAR340 - 3 2026-07-16

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-25 AAR360 HGH → ICN Jul 25, 03:55 UTCJul 25, 09:25 UTC5h 30m
2026-07-24 AAR736 SGN → ICN Jul 24, 22:55 UTCJul 24, 23:15 UTC20m
2026-07-24 AAR735 ICN → SGN Jul 24, 11:15 UTCJul 24, 22:10 UTC10h 55m
2026-07-24 AAR372 SZX → ICN Jul 24, 08:35 UTCJul 24, 09:20 UTC45m
2026-07-24 AAR372 SZX → ICN Jul 24, 06:10 UTCJul 24, 06:25 UTC15m
2026-07-24 AAR371 ICN → SZX Jul 24, 04:20 UTCJul 24, 04:40 UTC20m
2026-07-24 AAR371 ICN → SZX Jul 24, 01:40 UTCJul 24, 02:20 UTC40m
2026-07-23 AAR322 CSX → ICN Jul 23, 19:05 UTCJul 23, 19:30 UTC25m
2026-07-23 AAR321 ICN → CSX Jul 23, 12:35 UTCJul 23, 13:05 UTC30m
2026-07-23 AAR744 BKK → ICN Jul 23, 05:40 UTCJul 23, 11:05 UTC5h 25m
2026-07-22 AAR743 ICN → BKK Jul 22, 22:40 UTCJul 23, 04:00 UTC5h 20m
2026-07-22 AAR1031 - Jul 22, 04:35 UTCJul 22, 05:25 UTC50m
2026-07-22 AAR1041 ICN → NRT Jul 22, 00:50 UTCJul 22, 02:45 UTC1h 55m
2026-07-21 AAR740 PNH → ICN Jul 21, 10:05 UTCJul 21, 21:40 UTC11h 35m
2026-07-21 AAR722 HKG → ICN Jul 21, 05:15 UTCJul 21, 08:30 UTC3h 15m
2026-07-21 AAR721 ICN → HKG Jul 21, 00:45 UTCJul 21, 03:50 UTC3h 5m
2026-07-20 AAR744 BKK → ICN Jul 20, 07:35 UTCJul 20, 10:25 UTC2h 50m
2026-07-20 AAR744 BKK → ICN Jul 20, 05:15 UTCJul 20, 05:30 UTC15m
2026-07-19 AAR743 - Jul 19, 22:30 UTCJul 20, 01:20 UTC2h 50m
2026-07-19 AAR755 ICN → ICN Jul 19, 10:20 UTCJul 19, 20:45 UTC10h 25m
2026-07-19 AAR722 - Jul 19, 05:15 UTCJul 19, 08:30 UTC3h 15m
2026-07-19 AAR721 ICN → HKG Jul 19, 00:40 UTCJul 19, 03:45 UTC3h 5m
2026-07-18 AAR372 - Jul 18, 08:50 UTCJul 18, 09:25 UTC35m
2026-07-18 AAR372 - Jul 18, 06:25 UTCJul 18, 06:35 UTC10m
2026-07-18 AAR371 - Jul 18, 01:39 UTCJul 18, 02:09 UTC30m
2026-07-17 AAR735 ICN → ICN Jul 17, 11:15 UTCJul 17, 23:05 UTC11h 50m
2026-07-17 AAR372 - Jul 17, 08:45 UTCJul 17, 09:20 UTC35m
2026-07-17 AAR372 - Jul 17, 06:20 UTCJul 17, 06:29 UTC10m
2026-07-17 AAR371 - Jul 17, 04:44 UTCJul 17, 04:54 UTC10m
2026-07-17 AAR371 - Jul 17, 01:49 UTCJul 17, 02:34 UTC45m
2026-07-16 AAR736 SGN → ICN Jul 16, 10:59 UTCJul 16, 22:59 UTC12h 0m
2026-07-16 AAR340 - Jul 16, 08:25 UTCJul 16, 08:45 UTC20m
2026-07-16 AAR339 - Jul 16, 03:45 UTCJul 16, 04:10 UTC25m
2026-07-15 AAR746 HKG → ICN Jul 15, 18:20 UTCJul 15, 21:35 UTC3h 15m
2026-07-15 AAR745 ICN → HKG Jul 15, 12:20 UTCJul 15, 15:20 UTC3h 0m
2026-07-15 AAR744 - Jul 15, 05:05 UTCJul 15, 10:25 UTC5h 20m
2026-07-15 AAR743 - Jul 15, 03:20 UTCJul 15, 03:30 UTC10m
2026-07-14 AAR743 - Jul 14, 22:25 UTCJul 15, 01:10 UTC2h 44m
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

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 Jul 25, 09:30 UTC.
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.