sensors Mode-S transponder

A71B43

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N557UW · AIRBUS A-321 · operated by AMERICAN AIRLINES INC

Hex
A71B43
Octal
51615503
Decimal
10,951,491
Country
US
Tail
N557UW
Type
A321
Transponder active on ground
Flights observed
15
Distinct callsigns
7
Country
US
Last broadcast
1d ago

Last known position

Most recent position reported by Mode-S A71B43.

Country allocation

The ICAO 24-bit address A71B43 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 7 distinct

Callsign Airline Flights Last seen
AAL1853 American Airlines 4 2026-04-13
AAL661 American Airlines 3 2026-04-13
AAL447 - 3 2026-04-13
AAL1311 - 2 2026-04-13
AAL1710 - 1 2026-04-13
AAL1640 - 1 2026-04-13
AAL1333 American Airlines 1 2026-04-12

Recent flights last 15

DateFlightRouteTakeoffLandingDuration
2026-04-13 AAL1640 MCO → MCO Apr 13, 21:55 UTCApr 13, 23:12 UTC1h 17m
2026-04-13 AAL1311 - Apr 13, 19:50 UTCApr 13, 20:25 UTC35m
2026-04-13 AAL1311 - Apr 13, 18:24 UTCApr 13, 20:23 UTC1h 59m
2026-04-13 AAL1710 - Apr 13, 14:20 UTCApr 13, 15:37 UTC1h 17m
2026-04-13 AAL447 - Apr 13, 12:20 UTCApr 13, 12:45 UTC25m
2026-04-13 AAL447 - Apr 13, 11:55 UTCApr 13, 12:45 UTC50m
2026-04-13 AAL447 - Apr 13, 11:21 UTCApr 13, 12:47 UTC1h 26m
2026-04-13 AAL1853 LAS → DFW Apr 13, 08:20 UTCApr 13, 09:45 UTC1h 25m
2026-04-13 AAL1853 LAS → DFW Apr 13, 07:55 UTCApr 13, 09:45 UTC1h 50m
2026-04-13 AAL1853 LAS → DFW Apr 13, 06:41 UTCApr 13, 09:43 UTC3h 2m
2026-04-13 AAL1853 LAS → DFW Apr 13, 04:30 UTCApr 13, 04:55 UTC25m
2026-04-13 AAL661 PHL → LAS Apr 13, 03:55 UTCApr 13, 04:55 UTC1h 0m
2026-04-13 AAL661 PHL → LAS Apr 13, 00:20 UTCApr 13, 04:15 UTC3h 55m
2026-04-12 AAL661 PHL → LAS Apr 12, 23:58 UTCApr 13, 05:09 UTC5h 11m
2026-04-12 AAL1333 SDF → MIA Apr 12, 17:40 UTCApr 12, 20:15 UTC2h 35m

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 N557UW page for operator, model, and routing details .

Mode-S A71B43 frequently asked

What is Mode-S code A71B43?
A71B43 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N557UW.
Where is Mode-S A71B43 registered?
Mode-S code A71B43 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 A71B43 broadcasting right now?
Mode-S A71B43 is currently broadcasting from the ground.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A71B43, octal 51615503, decimal 10,951,491.
What flights does A71B43 operate?
Mode-S A71B43 has broadcast 7 distinct callsigns, including AAL1853, AAL661, AAL447, AAL1311, AAL1710.