sensors Mode-S transponder

A12B4D

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N17461 · operated by UNITED AIRLINES INC

Hex
A12B4D
Octal
50225515
Decimal
10,562,381
Country
US
Tail
N17461
Broadcasting now · callsign BOE961 · 5,650 ft
Flights observed
5
Distinct callsigns
2
Country
US
Last broadcast
1h ago

Current position

A12B4D is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address A12B4D 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
BOE123 - 4 2026-06-08
BOE961 - 1 2026-06-12

Recent flights last 5

DateFlightRouteTakeoffLandingDuration
2026-06-12 BOE961 - Jun 12, 18:15 UTCJun 12, 19:15 UTC1h 0m
2026-06-08 BOE123 RNT → RNT Jun 8, 09:25 UTCJun 8, 09:35 UTC10m
2026-06-08 BOE123 RNT → RNT Jun 8, 09:00 UTCJun 8, 09:10 UTC10m
2026-06-08 BOE123 RNT → RNT Jun 8, 08:45 UTCJun 8, 08:55 UTC10m
2026-06-08 BOE123 RNT → RNT Jun 8, 04:35 UTCJun 8, 04:50 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 N17461 page for operator, model, and routing details .

Mode-S A12B4D frequently asked

What is Mode-S code A12B4D?
A12B4D is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N17461.
Where is Mode-S A12B4D registered?
Mode-S code A12B4D 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 A12B4D broadcasting right now?
Yes. Mode-S A12B4D is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A12B4D, octal 50225515, decimal 10,562,381.
What flights does A12B4D operate?
Mode-S A12B4D has broadcast 2 distinct callsigns, including BOE123, BOE961.