sensors Mode-S transponder

A8A391

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N656FR · operated by BANK OF UTAH TRUSTEE

Hex
A8A391
Octal
52121621
Decimal
11,051,921
Country
US
Tail
N656FR
Type
A21N
No current signal · last broadcast 23h ago
Flights observed
11
Distinct callsigns
6
Country
US
Last broadcast
23h ago

Last known position

Most recent position reported by Mode-S A8A391.

Country allocation

The ICAO 24-bit address A8A391 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 6 distinct

Callsign Airline Flights Last seen
FFT1577 - 3 2026-04-13
FFT3480 - 2 2026-04-13
FFT2861 Frontier Airlines 2 2026-04-13
FFT2026 - 2 2026-04-13
FFT4781 - 1 2026-04-13
FFT23 - 1 2026-04-12

Recent flights last 11

DateFlightRouteTakeoffLandingDuration
2026-04-13 FFT4781 - Apr 13, 21:57 UTCApr 14, 00:45 UTC2h 48m
2026-04-13 FFT2026 - Apr 13, 19:50 UTCApr 13, 20:20 UTC30m
2026-04-13 FFT2026 - Apr 13, 18:00 UTCApr 13, 20:10 UTC2h 10m
2026-04-13 FFT1577 - Apr 13, 16:15 UTCApr 13, 16:30 UTC15m
2026-04-13 FFT1577 COI → RSW Apr 13, 15:50 UTCApr 13, 16:30 UTC40m
2026-04-13 FFT1577 - Apr 13, 14:05 UTCApr 13, 16:15 UTC2h 10m
2026-04-13 FFT3480 - Apr 13, 03:55 UTCApr 13, 04:15 UTC20m
2026-04-13 FFT3480 - Apr 13, 02:30 UTCApr 13, 04:15 UTC1h 45m
2026-04-13 FFT2861 PHL → JAX Apr 13, 00:20 UTCApr 13, 00:55 UTC35m
2026-04-12 FFT2861 PHL → JAX Apr 12, 23:55 UTCApr 13, 00:55 UTC1h 0m
2026-04-12 FFT23 - Apr 12, 19:20 UTCApr 12, 20:10 UTC50m

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 N656FR page for operator, model, and routing details .

Mode-S A8A391 frequently asked

What is Mode-S code A8A391?
A8A391 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N656FR.
Where is Mode-S A8A391 registered?
Mode-S code A8A391 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 A8A391 broadcasting right now?
No active broadcast right now. Last signal was 23h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A8A391, octal 52121621, decimal 11,051,921.
What flights does A8A391 operate?
Mode-S A8A391 has broadcast 6 distinct callsigns, including FFT1577, FFT3480, FFT2861, FFT2026, FFT4781.