sensors Mode-S transponder

71C321

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

Currently assigned to HL8321 · BOEING 737-800

Hex
71C321
Octal
34341441
Decimal
7,455,521
Country
KR
Tail
HL8321
Type
B738
No current signal · last broadcast 13h ago
Flights observed
13
Distinct callsigns
10
Country
KR
Last broadcast
13h ago

Last known position

Most recent position reported by Mode-S 71C321.

Country allocation

The ICAO 24-bit address 71C321 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 10 distinct

Callsign Airline Flights Last seen
JJA226 - 2 2026-04-14
JJA1328 - 2 2026-04-13
JJA1325 Jeju Air 2 2026-04-13
JJA225 - 1 2026-04-14
JJA151 - 1 2026-04-13
JJA138 - 1 2026-04-13
JJA137 - 1 2026-04-13
JJA1327 - 1 2026-04-13
JJA1326 Jeju Air 1 2026-04-13
JJA127 - 1 2026-04-14

Recent flights last 13

DateFlightRouteTakeoffLandingDuration
2026-04-14 JJA225 - Apr 14, 10:25 UTCApr 14, 10:55 UTC30m
2026-04-14 JJA226 - Apr 14, 09:10 UTCApr 14, 09:20 UTC10m
2026-04-14 JJA226 - Apr 14, 08:50 UTCApr 14, 09:05 UTC15m
2026-04-14 JJA127 - Apr 14, 06:25 UTCApr 14, 07:00 UTC35m
2026-04-13 JJA151 - Apr 13, 21:35 UTCApr 13, 22:10 UTC35m
2026-04-13 JJA138 - Apr 13, 12:45 UTCApr 13, 13:25 UTC40m
2026-04-13 JJA137 - Apr 13, 10:35 UTCApr 13, 11:10 UTC35m
2026-04-13 JJA1328 - Apr 13, 08:20 UTCApr 13, 09:15 UTC55m
2026-04-13 JJA1328 - Apr 13, 07:55 UTCApr 13, 08:15 UTC20m
2026-04-13 JJA1327 - Apr 13, 05:05 UTCApr 13, 06:05 UTC1h 0m
2026-04-13 JJA1326 KIX → GMP Apr 13, 02:25 UTCApr 13, 03:35 UTC1h 10m
2026-04-13 JJA1325 GMP → KIX Apr 13, 00:20 UTCApr 13, 00:30 UTC10m
2026-04-12 JJA1325 GMP → KIX Apr 12, 23:55 UTCApr 13, 00:30 UTC35m

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 HL8321 page for operator, model, and routing details .

Mode-S 71C321 frequently asked

What is Mode-S code 71C321?
71C321 is an ICAO 24-bit transponder address. Allocated to Korea, South. Assigned to HL8321.
Where is Mode-S 71C321 registered?
Mode-S code 71C321 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 71C321 broadcasting right now?
No active broadcast right now. Last signal was 13h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 71C321, octal 34341441, decimal 7,455,521.
What flights does 71C321 operate?
Mode-S 71C321 has broadcast 10 distinct callsigns, including JJA226, JJA1328, JJA1325, JJA225, JJA151.