sensors Mode-S transponder

A55B50

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N444UW · AIRBUS A-321neo · operated by AMERICAN AIRLINES INC

Hex
A55B50
Octal
51255520
Decimal
10,836,816
Country
US
Tail
N444UW
Type
A21N
No current signal · last broadcast 15h ago
Flights observed
11
Distinct callsigns
5
Country
US
Last broadcast
15h ago

Last known position

Most recent position reported by Mode-S A55B50.

Country allocation

The ICAO 24-bit address A55B50 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 5 distinct

Callsign Airline Flights Last seen
AAL2701 - 3 2026-04-14
AAL1511 American Airlines 3 2026-04-13
AAL2277 - 2 2026-04-13
AAL2838 - 1 2026-04-12
AAL1762 - 1 2026-04-13

Recent flights last 11

DateFlightRouteTakeoffLandingDuration
2026-04-14 AAL2701 - Apr 14, 09:10 UTCApr 14, 09:25 UTC15m
2026-04-14 AAL2701 - Apr 14, 07:10 UTCApr 14, 09:05 UTC1h 55m
2026-04-14 AAL2701 - Apr 14, 05:29 UTCApr 14, 09:51 UTC4h 22m
2026-04-13 AAL1762 - Apr 13, 21:05 UTCApr 13, 23:40 UTC2h 35m
2026-04-13 AAL1511 MIA → SDQ Apr 13, 16:15 UTCApr 13, 18:25 UTC2h 10m
2026-04-13 AAL1511 MIA → SDQ Apr 13, 15:50 UTCApr 13, 18:25 UTC2h 35m
2026-04-13 AAL1511 MIA → SDQ Apr 13, 14:25 UTCApr 13, 18:17 UTC3h 52m
2026-04-13 - PHX → PHX Apr 13, 05:25 UTCApr 13, 05:40 UTC15m
2026-04-13 AAL2277 - Apr 13, 00:20 UTCApr 13, 02:30 UTC2h 10m
2026-04-12 AAL2277 - Apr 12, 23:55 UTCApr 13, 02:30 UTC2h 35m
2026-04-12 AAL2838 - Apr 12, 17:55 UTCApr 12, 20:15 UTC2h 20m

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 N444UW page for operator, model, and routing details .

Mode-S A55B50 frequently asked

What is Mode-S code A55B50?
A55B50 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N444UW.
Where is Mode-S A55B50 registered?
Mode-S code A55B50 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 A55B50 broadcasting right now?
No active broadcast right now. Last signal was 15h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A55B50, octal 51255520, decimal 10,836,816.
What flights does A55B50 operate?
Mode-S A55B50 has broadcast 5 distinct callsigns, including AAL2701, AAL1511, AAL2277, AAL2838, AAL1762.