sensors Mode-S transponder

45CAA1

ICAO 24-bit transponder address · allocated to Denmark

Currently assigned to OY-RUA · ATR-72-500

Hex
45CAA1
Octal
21345241
Decimal
4,573,857
Country
DK
Tail
OY-RUA
Type
AT75
Broadcasting now · callsign DTR192 · 19,000 ft
Flights observed
8
Distinct callsigns
4
Country
DK
Last broadcast
22h ago

Current position

45CAA1 is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address 45CAA1 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 4 distinct

Callsign Airline Flights Last seen
DTR191 DAT Danish Air Transport 3 2026-04-14
DTR194 DAT Danish Air Transport 2 2026-04-13
DTR192 DAT Danish Air Transport 2 2026-04-14
DTR193 - 1 2026-04-13

Recent flights last 8

DateFlightRouteTakeoffLandingDuration
2026-04-14 DTR192 FRA → LNZ Apr 14, 07:10 UTCApr 14, 08:10 UTC1h 0m
2026-04-14 DTR191 LNZ → FRA Apr 14, 05:15 UTCApr 14, 05:25 UTC10m
2026-04-13 DTR194 FRA → LNZ Apr 13, 12:20 UTCApr 13, 13:00 UTC40m
2026-04-13 DTR194 FRA → LNZ Apr 13, 11:55 UTCApr 13, 12:15 UTC20m
2026-04-13 DTR193 LNZ → FRA Apr 13, 09:45 UTCApr 13, 11:00 UTC1h 15m
2026-04-13 DTR192 FRA → LNZ Apr 13, 06:35 UTCApr 13, 07:45 UTC1h 10m
2026-04-13 DTR191 - Apr 13, 04:20 UTCApr 13, 05:10 UTC50m
2026-04-13 DTR191 - Apr 13, 04:00 UTCApr 13, 04:15 UTC15m

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

Mode-S 45CAA1 frequently asked

What is Mode-S code 45CAA1?
45CAA1 is an ICAO 24-bit transponder address. Allocated to Denmark. Assigned to OY-RUA.
Where is Mode-S 45CAA1 registered?
Mode-S code 45CAA1 is allocated to Denmark (DK). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 45CAA1 broadcasting right now?
Yes. Mode-S 45CAA1 is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 45CAA1, octal 21345241, decimal 4,573,857.
What flights does 45CAA1 operate?
Mode-S 45CAA1 has broadcast 4 distinct callsigns, including DTR191, DTR194, DTR192, DTR193.