sensors Mode-S transponder

4C31E1

ICAO 24-bit transponder address · allocated to Serbia

Currently assigned to YU-MPB · CESSNA 560XL Citation XLS

Hex
4C31E1
Octal
23030741
Decimal
4,993,505
Country
RS
Tail
YU-MPB
Type
C56X
No current signal · last broadcast 1d ago
Flights observed
7
Distinct callsigns
1
Country
RS
Last broadcast
1d ago

Last known position

Most recent position reported by Mode-S 4C31E1.

Country allocation

The ICAO 24-bit address 4C31E1 falls within the block assigned to Serbia (RS) by ICAO Annex 10, Volume III. Every aircraft registered in Serbia 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 1 distinct

Callsign Airline Flights Last seen
MPC003 - 7 2026-04-13

Recent flights last 7

DateFlightRouteTakeoffLandingDuration
2026-04-13 MPC003 - Apr 13, 19:50 UTCApr 13, 20:30 UTC40m
2026-04-13 MPC003 - Apr 13, 18:15 UTCApr 13, 20:10 UTC1h 55m
2026-04-13 MPC003 - Apr 13, 16:15 UTCApr 13, 17:10 UTC55m
2026-04-13 MPC003 - Apr 13, 15:55 UTCApr 13, 16:15 UTC20m
2026-04-13 MPC003 - Apr 13, 09:05 UTCApr 13, 09:35 UTC30m
2026-04-13 MPC003 - Apr 13, 07:50 UTCApr 13, 08:10 UTC20m
2026-04-12 MPC003 - Apr 12, 18:10 UTCApr 12, 18:30 UTC20m

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 YU-MPB page for operator, model, and routing details .

Mode-S 4C31E1 frequently asked

What is Mode-S code 4C31E1?
4C31E1 is an ICAO 24-bit transponder address. Allocated to Serbia. Assigned to YU-MPB.
Where is Mode-S 4C31E1 registered?
Mode-S code 4C31E1 is allocated to Serbia (RS). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 4C31E1 broadcasting right now?
No active broadcast right now. Last signal was 1d ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 4C31E1, octal 23030741, decimal 4,993,505.
What flights does 4C31E1 operate?
Mode-S 4C31E1 has broadcast 1 distinct callsign, including MPC003.