sensors Mode-S transponder

501C5E

ICAO 24-bit transponder address · allocated to Croatia

Currently assigned to 9A-ATR · ATR-72-600

Hex
501C5E
Octal
24016136
Decimal
5,250,142
Country
HR
Tail
9A-ATR
Type
AT76
No current signal · last broadcast 12h ago
Flights observed
9
Distinct callsigns
7
Country
HR
Last broadcast
12h ago

Last known position

Most recent position reported by Mode-S 501C5E.

Country allocation

The ICAO 24-bit address 501C5E falls within the block assigned to Croatia (HR) by ICAO Annex 10, Volume III. Every aircraft registered in Croatia 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 7 distinct

Callsign Airline Flights Last seen
CTN4AT - 2 2026-04-14
CTN437 - 2 2026-04-13
CTN660 - 1 2026-04-14
CTN441 - 1 2026-04-14
CTN436 Croatia Airlines 1 2026-04-13
CTN345 - 1 2026-04-13
CTN344 - 1 2026-04-13

Recent flights last 9

DateFlightRouteTakeoffLandingDuration
2026-04-14 CTN660 - Apr 14, 09:55 UTCApr 14, 10:50 UTC55m
2026-04-14 CTN441 - Apr 14, 08:10 UTCApr 14, 08:55 UTC45m
2026-04-14 CTN4AT - Apr 14, 07:10 UTCApr 14, 07:15 UTC5m
2026-04-14 CTN4AT - Apr 14, 06:30 UTCApr 14, 07:10 UTC40m
2026-04-13 CTN437 - Apr 13, 19:50 UTCApr 13, 20:20 UTC30m
2026-04-13 CTN437 - Apr 13, 19:15 UTCApr 13, 20:10 UTC55m
2026-04-13 CTN436 ZAG → MUC Apr 13, 17:10 UTCApr 13, 18:15 UTC1h 5m
2026-04-13 CTN345 - Apr 13, 15:10 UTCApr 13, 15:40 UTC30m
2026-04-13 CTN344 - Apr 13, 13:25 UTCApr 13, 14:00 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 9A-ATR page for operator, model, and routing details .

Mode-S 501C5E frequently asked

What is Mode-S code 501C5E?
501C5E is an ICAO 24-bit transponder address. Allocated to Croatia. Assigned to 9A-ATR.
Where is Mode-S 501C5E registered?
Mode-S code 501C5E is allocated to Croatia (HR). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 501C5E broadcasting right now?
No active broadcast right now. Last signal was 12h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 501C5E, octal 24016136, decimal 5,250,142.
What flights does 501C5E operate?
Mode-S 501C5E has broadcast 7 distinct callsigns, including CTN4AT, CTN437, CTN660, CTN441, CTN436.