Apparatus

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sensors Mode-S transponder

71C503

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

Currently assigned to HL8503 · BOEING 737-800

Hex
71C503
Octal
34342403
Decimal
7,456,003
Country
KR
Tail
HL8503
Type
B738
No current signal · last broadcast Jul 24, 22:15 UTC
Flights observed
114
Distinct callsigns
20
Country
KR
Last broadcast
Jul 24, 22:15 UTC

Last known position

Most recent position reported by Mode-S 71C503.

Country allocation

The ICAO 24-bit address 71C503 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
AIH374 - 19 2026-07-21
AIH373 - 17 2026-07-21
AIH371 - 12 2026-07-22
AIH372 - 10 2026-07-22
AIH925 - 7 2026-07-10
AIH973 - 6 2026-07-23
AIH926 - 5 2026-07-10
AIH918 - 5 2026-07-23
AIH917 Alpine Air Chile 5 2026-07-23
AIH974 Alpine Air Chile 4 2026-07-23
AIH182 - 4 2026-06-11
AIH181 Alpine Air Chile 4 2026-06-11
AIH927 - 2 2026-05-15
AIH986 - 1 2026-06-17
AIH985 - 1 2026-06-17
AIH978 - 1 2026-06-09
AIH977 - 1 2026-06-09
AIH972 Alpine Air Chile 1 2026-07-24
AIH971 Alpine Air Chile 1 2026-07-24
AIH947 - 1 2026-05-26

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-24 AIH972 HKG → ICN Jul 24, 19:00 UTCJul 24, 22:15 UTC3h 15m
2026-07-24 AIH971 ICN → HKG Jul 24, 14:05 UTCJul 24, 17:10 UTC3h 5m
2026-07-23 AIH974 HKG → ICN Jul 23, 18:55 UTCJul 23, 22:10 UTC3h 15m
2026-07-23 AIH973 ICN → HKG Jul 23, 14:20 UTCJul 23, 17:30 UTC3h 10m
2026-07-23 AIH918 - Jul 23, 10:35 UTCJul 23, 11:05 UTC30m
2026-07-23 AIH917 BFS → AGP Jul 23, 03:55 UTCJul 23, 04:15 UTC20m
2026-07-22 AIH372 - Jul 22, 20:50 UTCJul 23, 00:45 UTC3h 55m
2026-07-22 AIH371 - Jul 22, 14:30 UTCJul 22, 15:15 UTC45m
2026-07-21 AIH374 - Jul 21, 19:50 UTCJul 21, 23:50 UTC4h 0m
2026-07-21 AIH373 - Jul 21, 14:35 UTCJul 21, 15:15 UTC40m
2026-07-16 AIH374 - Jul 16, 23:20 UTCJul 16, 23:59 UTC40m
2026-07-16 AIH373 - Jul 16, 14:20 UTCJul 16, 15:05 UTC45m
2026-07-15 AIH920 - Jul 15, 00:05 UTCJul 15, 00:30 UTC25m
2026-07-14 AIH919 - Jul 14, 15:50 UTCJul 14, 23:15 UTC7h 24m
2026-07-10 AIH372 - Jul 10, 23:30 UTCJul 11, 00:15 UTC45m
2026-07-10 AIH372 - Jul 10, 19:55 UTCJul 10, 20:05 UTC10m
2026-07-10 AIH371 - Jul 10, 14:05 UTCJul 10, 14:45 UTC40m
2026-07-10 AIH926 - Jul 10, 05:50 UTCJul 10, 06:15 UTC25m
2026-07-10 AIH925 - Jul 10, 02:50 UTCJul 10, 03:15 UTC25m
2026-07-09 AIH374 - Jul 9, 23:35 UTCJul 10, 00:15 UTC40m
2026-07-09 AIH373 - Jul 9, 14:20 UTCJul 9, 15:05 UTC45m
2026-07-09 AIH918 - Jul 9, 10:55 UTCJul 9, 11:30 UTC35m
2026-07-09 AIH917 - Jul 9, 04:05 UTCJul 9, 04:35 UTC30m
2026-07-07 AIH374 - Jul 7, 23:00 UTCJul 7, 23:45 UTC45m
2026-07-07 AIH374 - Jul 7, 19:50 UTCJul 7, 20:05 UTC15m
2026-07-07 AIH373 - Jul 7, 14:05 UTCJul 7, 14:50 UTC45m
2026-07-03 AIH372 - Jul 3, 19:55 UTCJul 3, 23:50 UTC3h 55m
2026-07-03 AIH371 - Jul 3, 17:50 UTCJul 3, 18:10 UTC20m
2026-07-03 AIH371 - Jul 3, 14:25 UTCJul 3, 15:05 UTC40m
2026-07-02 AIH374 - Jul 2, 19:45 UTCJul 2, 23:40 UTC3h 55m
2026-07-02 AIH373 - Jul 2, 14:15 UTCJul 2, 18:10 UTC3h 55m
2026-06-30 AIH374 - Jun 30, 19:50 UTCJun 30, 23:35 UTC3h 45m
2026-06-30 AIH373 - Jun 30, 14:10 UTCJun 30, 18:05 UTC3h 55m
2026-06-29 AIH918 - Jun 29, 10:55 UTCJun 29, 11:25 UTC30m
2026-06-29 AIH917 - Jun 29, 04:00 UTCJun 29, 04:25 UTC25m
2026-06-26 AIH372 - Jun 26, 19:55 UTCJun 26, 23:34 UTC3h 40m
2026-06-26 AIH371 - Jun 26, 14:19 UTCJun 26, 18:29 UTC4h 10m
2026-06-25 AIH374 - Jun 25, 19:49 UTCJun 25, 23:44 UTC3h 55m
2026-06-25 AIH373 - Jun 25, 14:14 UTCJun 25, 18:19 UTC4h 5m
2026-06-23 AIH374 - Jun 23, 20:04 UTCJun 23, 23:59 UTC3h 55m
2026-06-23 AIH373 - Jun 23, 14:35 UTCJun 23, 18:25 UTC3h 50m
2026-06-18 AIH374 - Jun 18, 19:55 UTCJun 19, 00:00 UTC4h 5m
2026-06-18 AIH373 - Jun 18, 14:30 UTCJun 18, 18:20 UTC3h 50m
2026-06-17 AIH986 - Jun 17, 07:25 UTCJun 17, 07:50 UTC25m
2026-06-17 AIH985 - Jun 17, 04:25 UTCJun 17, 04:40 UTC15m
2026-06-16 AIH374 - Jun 16, 20:10 UTCJun 17, 00:00 UTC3h 50m
2026-06-16 AIH373 - Jun 16, 14:25 UTCJun 16, 18:20 UTC3h 55m
2026-06-12 AIH372 HAN → ICN Jun 12, 19:55 UTCJun 12, 23:50 UTC3h 55m
2026-06-12 AIH371 - Jun 12, 17:55 UTCJun 12, 18:05 UTC10m
2026-06-12 AIH371 - Jun 12, 14:10 UTCJun 12, 14:50 UTC40m

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 HL8503 page for operator, model, and routing details .

Mode-S 71C503 frequently asked

What is Mode-S code 71C503?
71C503 is an ICAO 24-bit transponder address. Allocated to Korea, South. Assigned to HL8503.
Where is Mode-S 71C503 registered?
Mode-S code 71C503 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 71C503 broadcasting right now?
No active broadcast right now. Last signal was Jul 24, 22:15 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 71C503, octal 34342403, decimal 7,456,003.
What flights does 71C503 operate?
Mode-S 71C503 has broadcast 20 distinct callsigns, including AIH374, AIH373, AIH371, AIH372, AIH925.