Apparatus

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sensors Mode-S transponder

71C581

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

Currently assigned to HL8581 · BOEING 737 MAX 8

Hex
71C581
Octal
34342601
Decimal
7,456,129
Country
KR
Tail
HL8581
Type
B38M
No current signal · last broadcast 3h ago
Flights observed
301
Distinct callsigns
20
Country
KR
Last broadcast
3h ago

Last known position

Most recent position reported by Mode-S 71C581.

Country allocation

The ICAO 24-bit address 71C581 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
TWB282 - 29 2026-07-12
TWB281 - 28 2026-07-12
TWB246 - 21 2026-07-08
TWB245 - 20 2026-07-14
TWB302 - 18 2026-07-14
TWB301 - 18 2026-07-13
TWB206 - 16 2026-07-10
TWB205 - 15 2026-07-10
TWB202 - 11 2026-06-30
TWB007 - 11 2026-07-08
TWB304 - 10 2026-07-13
TWB303 - 10 2026-07-13
TWB008 - 10 2026-07-10
TWB438 - 9 2026-07-12
TWB201 - 9 2026-06-30
TWB437 - 8 2026-07-11
TWB055 Tway Airlines 8 2026-04-28
TWB056 Tway Airlines 6 2026-04-27
TWB034 - 6 2026-07-07
TWB033 - 5 2026-06-29

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-14 TWB245 ICN → NRT Jul 14, 06:15 UTCJul 14, 08:10 UTC1h 55m
2026-07-14 TWB302 KIX → ICN Jul 14, 02:40 UTCJul 14, 04:05 UTC1h 25m
2026-07-13 TWB301 ICN → KIX Jul 13, 23:10 UTCJul 14, 00:35 UTC1h 25m
2026-07-13 TWB304 - Jul 13, 05:50 UTCJul 13, 07:10 UTC1h 20m
2026-07-13 TWB303 ICN → KIX Jul 13, 02:10 UTCJul 13, 03:40 UTC1h 30m
2026-07-12 TWB282 - Jul 12, 05:55 UTCJul 12, 07:40 UTC1h 45m
2026-07-12 TWB281 - Jul 12, 03:50 UTCJul 12, 04:10 UTC20m
2026-07-12 TWB281 - Jul 12, 02:25 UTCJul 12, 03:01 UTC35m
2026-07-12 TWB438 - Jul 12, 00:01 UTCJul 12, 00:25 UTC25m
2026-07-11 TWB438 - Jul 11, 12:00 UTCJul 11, 23:05 UTC11h 5m
2026-07-11 TWB437 - Jul 11, 10:50 UTCJul 11, 11:05 UTC15m
2026-07-10 TWB008 ICN → ICN Jul 10, 23:40 UTCJul 11, 09:10 UTC9h 30m
2026-07-10 TWB206 - Jul 10, 08:40 UTCJul 10, 09:40 UTC1h 0m
2026-07-10 TWB205 - Jul 10, 06:15 UTCJul 10, 07:10 UTC55m
2026-07-10 TWB302 KIX → ICN Jul 10, 02:55 UTCJul 10, 04:25 UTC1h 30m
2026-07-09 TWB301 ICN → KIX Jul 9, 23:15 UTCJul 10, 00:40 UTC1h 25m
2026-07-08 TWB007 ICN → ICN Jul 8, 23:25 UTCJul 9, 09:15 UTC9h 50m
2026-07-08 TWB246 NRT → ICN Jul 8, 10:30 UTCJul 8, 12:30 UTC2h 0m
2026-07-08 TWB245 ICN → NRT Jul 8, 06:20 UTCJul 8, 08:20 UTC2h 0m
2026-07-08 TWB302 KIX → ICN Jul 8, 02:50 UTCJul 8, 04:15 UTC1h 25m
2026-07-07 TWB301 ICN → KIX Jul 7, 23:20 UTCJul 8, 00:45 UTC1h 25m
2026-07-07 TWB034 ICN → ICN Jul 7, 10:05 UTCJul 7, 21:40 UTC11h 35m
2026-07-06 TWB282 - Jul 6, 06:05 UTCJul 6, 08:00 UTC1h 55m
2026-07-06 TWB281 - Jul 6, 04:10 UTCJul 6, 04:30 UTC20m
2026-07-06 TWB281 - Jul 6, 02:45 UTCJul 6, 03:20 UTC35m
2026-07-05 TWB282 - Jul 5, 06:20 UTCJul 5, 08:10 UTC1h 50m
2026-07-05 TWB281 - Jul 5, 03:55 UTCJul 5, 04:15 UTC20m
2026-07-05 TWB281 - Jul 5, 02:30 UTCJul 5, 03:05 UTC35m
2026-07-05 TWB438 - Jul 5, 00:15 UTCJul 5, 00:35 UTC20m
2026-07-04 TWB437 - Jul 4, 10:35 UTCJul 4, 23:25 UTC12h 50m
2026-07-03 TWB007 ICN → ICN Jul 3, 23:15 UTCJul 4, 09:05 UTC9h 50m
2026-07-03 TWB206 - Jul 3, 08:45 UTCJul 3, 09:40 UTC55m
2026-07-03 TWB205 - Jul 3, 06:05 UTCJul 3, 06:45 UTC40m
2026-07-03 TWB302 - Jul 3, 02:50 UTCJul 3, 04:20 UTC1h 30m
2026-07-02 TWB301 ICN → KIX Jul 2, 23:20 UTCJul 3, 00:35 UTC1h 15m
2026-07-02 TWB246 NRT → ICN Jul 2, 10:25 UTCJul 2, 12:30 UTC2h 5m
2026-07-02 TWB245 - Jul 2, 06:15 UTCJul 2, 08:05 UTC1h 50m
2026-07-02 TWB302 KIX → ICN Jul 2, 02:50 UTCJul 2, 04:25 UTC1h 35m
2026-07-01 TWB301 ICN → KIX Jul 1, 23:20 UTCJul 2, 00:45 UTC1h 25m
2026-07-01 TWB246 NRT → ICN Jul 1, 10:15 UTCJul 1, 12:15 UTC2h 0m
2026-07-01 TWB245 ICN → NRT Jul 1, 06:30 UTCJul 1, 08:25 UTC1h 55m
2026-07-01 TWB302 KIX → ICN Jul 1, 03:10 UTCJul 1, 04:35 UTC1h 25m
2026-06-30 TWB301 - Jun 30, 23:10 UTCJul 1, 00:35 UTC1h 25m
2026-06-30 TWB206 - Jun 30, 08:40 UTCJun 30, 09:40 UTC1h 0m
2026-06-30 TWB205 - Jun 30, 06:25 UTCJun 30, 07:10 UTC45m
2026-06-30 TWB202 - Jun 30, 03:45 UTCJun 30, 04:40 UTC55m
2026-06-30 TWB201 - Jun 30, 01:19 UTCJun 30, 02:05 UTC46m
2026-06-29 TWB033 ICN → ICN Jun 29, 10:10 UTCJun 29, 21:19 UTC11h 10m
2026-06-29 TWB304 KIX → ICN Jun 29, 05:54 UTCJun 29, 07:15 UTC1h 20m
2026-06-29 TWB303 ICN → KIX Jun 29, 02:14 UTCJun 29, 03:39 UTC1h 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 HL8581 page for operator, model, and routing details .

Mode-S 71C581 frequently asked

What is Mode-S code 71C581?
71C581 is an ICAO 24-bit transponder address. Allocated to Korea, South. Assigned to HL8581.
Where is Mode-S 71C581 registered?
Mode-S code 71C581 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 71C581 broadcasting right now?
No active broadcast right now. Last signal was 3h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 71C581, octal 34342601, decimal 7,456,129.
What flights does 71C581 operate?
Mode-S 71C581 has broadcast 20 distinct callsigns, including TWB282, TWB281, TWB246, TWB245, TWB302.