sensors Mode-S transponder

45B423

ICAO 24-bit transponder address · allocated to Denmark

Currently assigned to OY-MAC · BOEING 777-200LR

Hex
45B423
Octal
21332043
Decimal
4,568,099
Country
DK
Tail
OY-MAC
Type
B77L
No current signal · last broadcast 23h ago
Flights observed
9
Distinct callsigns
2
Country
DK
Last broadcast
23h ago

Last known position

Most recent position reported by Mode-S 45B423.

Country allocation

The ICAO 24-bit address 45B423 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 2 distinct

Callsign Airline Flights Last seen
SRR902 Star Air 7 2026-04-13
SRR901 Star Air 2 2026-04-14

Recent flights last 9

DateFlightRouteTakeoffLandingDuration
2026-04-14 SRR901 BLL → BLL Apr 14, 07:10 UTCApr 14, 07:45 UTC35m
2026-04-14 SRR901 BLL → BLL Apr 14, 05:15 UTCApr 14, 07:10 UTC1h 55m
2026-04-13 SRR902 BLL → BLL Apr 13, 15:50 UTCApr 13, 16:10 UTC20m
2026-04-13 SRR902 BLL → BLL Apr 13, 15:00 UTCApr 13, 16:10 UTC1h 10m
2026-04-13 SRR902 BLL → BLL Apr 13, 12:20 UTCApr 13, 12:40 UTC20m
2026-04-13 SRR902 BLL → BLL Apr 13, 11:55 UTCApr 13, 12:40 UTC45m
2026-04-13 SRR902 BLL → BLL Apr 13, 08:20 UTCApr 13, 12:15 UTC3h 55m
2026-04-13 SRR902 BLL → BLL Apr 13, 07:55 UTCApr 13, 11:50 UTC3h 55m
2026-04-13 SRR902 BLL → BLL Apr 13, 07:20 UTCApr 13, 08:15 UTC55m

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-MAC page for operator, model, and routing details .

Mode-S 45B423 frequently asked

What is Mode-S code 45B423?
45B423 is an ICAO 24-bit transponder address. Allocated to Denmark. Assigned to OY-MAC.
Where is Mode-S 45B423 registered?
Mode-S code 45B423 is allocated to Denmark (DK). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 45B423 broadcasting right now?
No active broadcast right now. Last signal was 23h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 45B423, octal 21332043, decimal 4,568,099.
What flights does 45B423 operate?
Mode-S 45B423 has broadcast 2 distinct callsigns, including SRR902, SRR901.