sensors Mode-S transponder

A0665B

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N125AX · BEECH 1900 · operated by ALASKA CENTRAL EXPRESS INC

Hex
A0665B
Octal
50063133
Decimal
10,511,963
Country
US
Tail
N125AX
Type
B190
No current signal · last broadcast 12h ago
Flights observed
9
Distinct callsigns
2
Country
US
Last broadcast
12h ago

Last known position

Most recent position reported by Mode-S A0665B.

Country allocation

The ICAO 24-bit address A0665B falls within the block assigned to United States (US) by ICAO Annex 10, Volume III. Every aircraft registered in United States 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
AER41 Alaska Central Express 8 2026-04-14
AER64 - 1 2026-04-12

Recent flights last 9

DateFlightRouteTakeoffLandingDuration
2026-04-14 AER41 PSG → ANC Apr 14, 09:55 UTCApr 14, 11:05 UTC1h 10m
2026-04-13 AER41 PSG → ANC Apr 13, 19:45 UTCApr 13, 20:10 UTC25m
2026-04-13 AER41 PSG → ANC Apr 13, 18:50 UTCApr 13, 19:10 UTC20m
2026-04-13 AER41 PSG → ANC Apr 13, 17:35 UTCApr 13, 18:15 UTC40m
2026-04-13 AER41 PSG → ANC Apr 13, 16:45 UTCApr 13, 16:55 UTC10m
2026-04-13 AER41 PSG → ANC Apr 13, 14:25 UTCApr 13, 14:50 UTC25m
2026-04-13 AER41 PSG → ANC Apr 13, 13:20 UTCApr 13, 13:35 UTC15m
2026-04-13 AER41 PSG → ANC Apr 13, 09:55 UTCApr 13, 11:05 UTC1h 10m
2026-04-12 AER64 - Apr 12, 17:15 UTCApr 12, 18:55 UTC1h 40m

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 N125AX page for operator, model, and routing details .

Mode-S A0665B frequently asked

What is Mode-S code A0665B?
A0665B is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N125AX.
Where is Mode-S A0665B registered?
Mode-S code A0665B is allocated to United States (US). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is A0665B 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 A0665B, octal 50063133, decimal 10,511,963.
What flights does A0665B operate?
Mode-S A0665B has broadcast 2 distinct callsigns, including AER41, AER64.