sensors Mode-S transponder

AA7F23

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N77580 · operated by UNITED AIRLINES INC

Hex
AA7F23
Octal
52477443
Decimal
11,173,667
Country
US
Tail
N77580
Type
B39M
Transponder active on ground
Flights observed
7
Distinct callsigns
5
Country
US
Last broadcast
1d ago

Last known position

Most recent position reported by Mode-S AA7F23.

Country allocation

The ICAO 24-bit address AA7F23 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
UAL363T - 2 2026-04-12
UAL1699 - 2 2026-04-13
UAL1704 United Airlines 1 2026-04-12
UAL1092 - 1 2026-04-13
UAL1026 - 1 2026-04-13

Recent flights last 7

DateFlightRouteTakeoffLandingDuration
2026-04-13 UAL1699 - Apr 13, 19:50 UTCApr 13, 20:15 UTC25m
2026-04-13 UAL1699 - Apr 13, 16:55 UTCApr 13, 20:10 UTC3h 15m
2026-04-13 UAL1026 - Apr 13, 13:25 UTCApr 13, 14:00 UTC35m
2026-04-13 UAL1092 - Apr 13, 01:45 UTCApr 13, 02:25 UTC40m
2026-04-12 UAL1704 EWR → MSP Apr 12, 19:55 UTCApr 12, 20:15 UTC20m
2026-04-12 UAL363T - Apr 12, 16:01 UTCApr 12, 17:56 UTC1h 55m
2026-04-12 UAL363T - Apr 12, 17:15 UTCApr 12, 18:00 UTC45m

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 N77580 page for operator, model, and routing details .

Mode-S AA7F23 frequently asked

What is Mode-S code AA7F23?
AA7F23 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N77580.
Where is Mode-S AA7F23 registered?
Mode-S code AA7F23 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 AA7F23 broadcasting right now?
Mode-S AA7F23 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 AA7F23, octal 52477443, decimal 11,173,667.
What flights does AA7F23 operate?
Mode-S AA7F23 has broadcast 5 distinct callsigns, including UAL363T, UAL1699, UAL1704, UAL1092, UAL1026.