Apparatus

Try JFK, AAL1290, BAW, or N225AN.

sensors Mode-S transponder

71C521

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

Currently assigned to HL8521 · AIRBUS A-350-900

Hex
71C521
Octal
34342441
Decimal
7,456,033
Country
KR
Tail
HL8521
Type
A359
No current signal · last broadcast 8d ago
Flights observed
242
Distinct callsigns
20
Country
KR
Last broadcast
8d ago

Last known position

Most recent position reported by Mode-S 71C521.

Country allocation

The ICAO 24-bit address 71C521 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
AAR761 - 14 2026-06-27
AAR522 - 13 2026-06-27
AAR502 - 13 2026-07-06
AAR501 - 13 2026-07-05
AAR542 - 12 2026-07-01
AAR547 - 11 2026-06-17
AAR541 - 11 2026-06-30
AAR751 - 10 2026-06-29
AAR548 - 10 2026-06-18
AAR521 Asiana Airlines 10 2026-06-25
AAR511 Asiana Airlines 10 2026-06-09
AAR752 Asiana Airlines 8 2026-06-29
AAR582 - 8 2026-07-03
AAR546 Asiana Airlines 8 2026-06-12
AAR512 Asiana Airlines 8 2026-06-10
AAR211 Asiana Airlines 8 2026-05-25
AAR762 - 7 2026-06-27
AAR581 - 7 2026-07-02
AAR545 Asiana Airlines 7 2026-06-11
AAR212 Asiana Airlines 7 2026-05-24

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-06 AAR502 - Jul 6, 04:35 UTCJul 6, 05:00 UTC25m
2026-07-05 AAR502 - Jul 5, 17:40 UTCJul 6, 03:45 UTC10h 5m
2026-07-05 AAR501 - Jul 5, 02:45 UTCJul 5, 14:45 UTC12h 0m
2026-07-05 AAR501 - Jul 5, 01:35 UTCJul 5, 01:55 UTC20m
2026-07-04 AAR203 - Jul 4, 06:20 UTCJul 4, 18:40 UTC12h 20m
2026-07-03 AAR204 - Jul 3, 14:15 UTCJul 4, 00:40 UTC10h 25m
2026-07-03 AAR582 - Jul 3, 07:05 UTCJul 3, 07:25 UTC20m
2026-07-02 AAR582 - Jul 2, 20:25 UTCJul 3, 06:05 UTC9h 40m
2026-07-02 AAR581 - Jul 2, 13:45 UTCJul 2, 18:05 UTC4h 20m
2026-07-02 AAR581 - Jul 2, 05:30 UTCJul 2, 05:45 UTC15m
2026-07-02 AAR111 KIX → ICN Jul 2, 01:45 UTCJul 2, 03:15 UTC1h 30m
2026-07-01 AAR112 - Jul 1, 22:10 UTCJul 1, 23:40 UTC1h 30m
2026-07-01 AAR542 - Jul 1, 04:40 UTCJul 1, 05:05 UTC25m
2026-06-30 AAR542 - Jun 30, 17:55 UTCJul 1, 03:45 UTC9h 50m
2026-06-30 AAR541 - Jun 30, 03:40 UTCJun 30, 15:30 UTC11h 50m
2026-06-30 AAR541 - Jun 30, 02:30 UTCJun 30, 02:40 UTC10m
2026-06-29 AAR752 SIN → ICN Jun 29, 18:14 UTCJun 29, 21:14 UTC3h 0m
2026-06-29 AAR752 SIN → ICN Jun 29, 15:04 UTCJun 29, 15:14 UTC10m
2026-06-29 AAR751 - Jun 29, 13:00 UTCJun 29, 13:19 UTC20m
2026-06-29 AAR751 - Jun 29, 07:50 UTCJun 29, 10:29 UTC2h 40m
2026-06-29 AAR502 - Jun 29, 04:55 UTCJun 29, 05:20 UTC25m
2026-06-28 AAR502 - Jun 28, 18:00 UTCJun 29, 04:04 UTC10h 5m
2026-06-28 AAR501 - Jun 28, 02:39 UTCJun 28, 14:45 UTC12h 5m
2026-06-28 AAR501 - Jun 28, 01:29 UTCJun 28, 01:44 UTC15m
2026-06-27 AAR762 - Jun 27, 16:30 UTCJun 27, 21:29 UTC5h 0m
2026-06-27 AAR761 - Jun 27, 12:29 UTCJun 27, 12:45 UTC15m
2026-06-27 AAR761 - Jun 27, 06:19 UTCJun 27, 11:04 UTC4h 45m
2026-06-27 AAR522 - Jun 27, 03:15 UTCJun 27, 03:40 UTC25m
2026-06-26 AAR522 - Jun 26, 16:09 UTCJun 27, 02:25 UTC10h 15m
2026-06-25 AAR521 ICN → LHR Jun 25, 23:34 UTCJun 26, 13:24 UTC13h 50m
2026-06-25 AAR752 SIN → ICN Jun 25, 18:24 UTCJun 25, 21:29 UTC3h 5m
2026-06-25 AAR751 - Jun 25, 12:54 UTCJun 25, 13:05 UTC10m
2026-06-25 AAR751 - Jun 25, 07:45 UTCJun 25, 10:25 UTC2h 40m
2026-06-25 AAR502 - Jun 25, 05:00 UTCJun 25, 05:25 UTC25m
2026-06-24 AAR502 - Jun 24, 18:09 UTCJun 25, 04:10 UTC10h 0m
2026-06-24 AAR501 - Jun 24, 02:40 UTCJun 24, 15:05 UTC12h 25m
2026-06-24 AAR501 - Jun 24, 01:24 UTCJun 24, 01:44 UTC20m
2026-06-23 AAR734 - Jun 23, 16:54 UTCJun 23, 20:34 UTC3h 40m
2026-06-23 AAR733 - Jun 23, 11:19 UTCJun 23, 15:09 UTC3h 50m
2026-06-23 AAR542 - Jun 23, 04:39 UTCJun 23, 05:15 UTC35m
2026-06-22 AAR542 - Jun 22, 18:19 UTCJun 23, 03:54 UTC9h 35m
2026-06-22 AAR541 ICN → FRA Jun 22, 02:19 UTCJun 22, 15:29 UTC13h 10m
2026-06-21 AAR742 - Jun 21, 19:00 UTCJun 21, 23:55 UTC4h 55m
2026-06-21 AAR741 - Jun 21, 11:20 UTCJun 21, 16:19 UTC5h 0m
2026-06-21 AAR582 - Jun 21, 07:29 UTCJun 21, 07:59 UTC30m
2026-06-20 AAR582 - Jun 20, 21:10 UTCJun 21, 06:40 UTC9h 30m
2026-06-20 AAR581 - Jun 20, 07:34 UTCJun 20, 19:09 UTC11h 35m
2026-06-20 AAR581 - Jun 20, 06:19 UTCJun 20, 06:39 UTC20m
2026-06-20 AAR522 - Jun 20, 03:44 UTCJun 20, 04:14 UTC30m
2026-06-19 AAR522 - Jun 19, 16:34 UTCJun 20, 02:59 UTC10h 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 HL8521 page for operator, model, and routing details .

Mode-S 71C521 frequently asked

What is Mode-S code 71C521?
71C521 is an ICAO 24-bit transponder address. Allocated to Korea, South. Assigned to HL8521.
Where is Mode-S 71C521 registered?
Mode-S code 71C521 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 71C521 broadcasting right now?
No active broadcast right now. Last signal was 8d ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 71C521, octal 34342441, decimal 7,456,033.
What flights does 71C521 operate?
Mode-S 71C521 has broadcast 20 distinct callsigns, including AAR761, AAR522, AAR502, AAR501, AAR542.