sensors Mode-S transponder

A12B2D

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N17454 · operated by UNITED AIRLINES INC

Hex
A12B2D
Octal
50225455
Decimal
10,562,349
Country
US
Tail
N17454
No current signal · last broadcast 1d ago
Flights observed
1
Distinct callsigns
1
Country
US
Last broadcast
1d ago

Last known position

Most recent position reported by Mode-S A12B2D.

Country allocation

The ICAO 24-bit address A12B2D 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 1 distinct

Callsign Airline Flights Last seen
BOE954 - 1 2026-04-19

Recent flights last 1

DateFlightRouteTakeoffLandingDuration
2026-04-19 BOE954 BFI → BFI Apr 19, 23:05 UTCApr 20, 00:20 UTC1h 15m

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 N17454 page for operator, model, and routing details .

Mode-S A12B2D frequently asked

What is Mode-S code A12B2D?
A12B2D is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N17454.
Where is Mode-S A12B2D registered?
Mode-S code A12B2D 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 A12B2D 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 A12B2D, octal 50225455, decimal 10,562,349.
What flights does A12B2D operate?
Mode-S A12B2D has broadcast 1 distinct callsign, including BOE954.