sensors Mode-S transponder

71C545

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

Currently assigned to HL8545 · BOEING 737-800

Hex
71C545
Octal
34342505
Decimal
7,456,069
Country
KR
Tail
HL8545
Type
B738
Broadcasting now · callsign ESR711 · 21,725 ft
Flights observed
12
Distinct callsigns
11
Country
KR
Last broadcast
12h ago

Current position

71C545 is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address 71C545 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 11 distinct

Callsign Airline Flights Last seen
ESR274 - 2 2026-04-14
ESR278 - 1 2026-04-13
ESR277 - 1 2026-04-13
ESR276 - 1 2026-04-13
ESR275 - 1 2026-04-13
ESR273 - 1 2026-04-13
ESR271 Eastar Jet 1 2026-04-13
ESR233 - 1 2026-04-14
ESR224 - 1 2026-04-14
ESR223 - 1 2026-04-14
ESR204 Eastar Jet 1 2026-04-13

Recent flights last 12

DateFlightRouteTakeoffLandingDuration
2026-04-14 ESR233 - Apr 14, 10:50 UTCApr 14, 11:05 UTC15m
2026-04-14 ESR224 - Apr 14, 09:15 UTCApr 14, 09:50 UTC35m
2026-04-14 ESR223 - Apr 14, 07:10 UTCApr 14, 07:45 UTC35m
2026-04-14 ESR274 - Apr 14, 05:30 UTCApr 14, 06:00 UTC30m
2026-04-13 ESR271 GMP → CJU Apr 13, 22:55 UTCApr 13, 23:25 UTC30m
2026-04-13 ESR278 - Apr 13, 12:55 UTCApr 13, 13:35 UTC40m
2026-04-13 ESR277 - Apr 13, 10:45 UTCApr 13, 11:15 UTC30m
2026-04-13 ESR276 - Apr 13, 09:10 UTCApr 13, 09:45 UTC35m
2026-04-13 ESR275 - Apr 13, 07:00 UTCApr 13, 07:30 UTC30m
2026-04-13 ESR274 - Apr 13, 05:15 UTCApr 13, 05:50 UTC35m
2026-04-13 ESR273 - Apr 13, 02:55 UTCApr 13, 03:25 UTC30m
2026-04-13 ESR204 CJU → GMP Apr 13, 00:25 UTCApr 13, 01:00 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 HL8545 page for operator, model, and routing details .

Mode-S 71C545 frequently asked

What is Mode-S code 71C545?
71C545 is an ICAO 24-bit transponder address. Allocated to Korea, South. Assigned to HL8545.
Where is Mode-S 71C545 registered?
Mode-S code 71C545 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 71C545 broadcasting right now?
Yes. Mode-S 71C545 is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 71C545, octal 34342505, decimal 7,456,069.
What flights does 71C545 operate?
Mode-S 71C545 has broadcast 11 distinct callsigns, including ESR274, ESR278, ESR277, ESR276, ESR275.