sensors Mode-S transponder

45B4EF

ICAO 24-bit transponder address · allocated to Denmark

Currently assigned to OY-MGO · DASSAULT Falcon 2000

Hex
45B4EF
Octal
21332357
Decimal
4,568,303
Country
DK
Tail
OY-MGO
Type
F2TH
No current signal · last broadcast 17h ago
Flights observed
2
Distinct callsigns
1
Country
DK
Last broadcast
17h ago

Last known position

Most recent position reported by Mode-S 45B4EF.

Country allocation

The ICAO 24-bit address 45B4EF falls within the block assigned to Denmark (DK) by ICAO Annex 10, Volume III. Every aircraft registered in Denmark 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
MMD6789 Air Alsie 2 2026-04-14

Recent flights last 2

DateFlightRouteTakeoffLandingDuration
2026-04-14 MMD6789 CPH → NCE Apr 14, 10:35 UTCApr 14, 11:05 UTC30m
2026-04-14 MMD6789 CPH → NCE Apr 14, 08:05 UTCApr 14, 08:35 UTC30m

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 OY-MGO page for operator, model, and routing details .

Mode-S 45B4EF frequently asked

What is Mode-S code 45B4EF?
45B4EF is an ICAO 24-bit transponder address. Allocated to Denmark. Assigned to OY-MGO.
Where is Mode-S 45B4EF registered?
Mode-S code 45B4EF is allocated to Denmark (DK). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 45B4EF broadcasting right now?
No active broadcast right now. Last signal was 17h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 45B4EF, octal 21332357, decimal 4,568,303.
What flights does 45B4EF operate?
Mode-S 45B4EF has broadcast 1 distinct callsign, including MMD6789.