Apparatus

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sensors Mode-S transponder

A21F57

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N236FR · AIRBUS A-320 · operated by BANK OF UTAH TRUSTEE

Hex
A21F57
Octal
50417527
Decimal
10,624,855
Country
US
Tail
N236FR
Type
A320
No current signal · last broadcast Jul 26, 21:45 UTC
Flights observed
498
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 21:45 UTC

Last known position

Most recent position reported by Mode-S A21F57.

Country allocation

The ICAO 24-bit address A21F57 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 20 distinct

Callsign Airline Flights Last seen
FFT3091 Frontier Airlines 10 2026-04-22
FFT4639 Frontier Airlines 8 2026-04-22
FFT3092 Frontier Airlines 7 2026-04-22
FFT9436 - 6 2026-07-02
FFT4685 Frontier Airlines 6 2026-05-29
FFT4505 Frontier Airlines 6 2026-07-20
FFT4241 - 6 2026-07-19
FFT4117 Frontier Airlines 6 2026-07-26
FFT2050 Frontier Airlines 6 2026-05-20
FFT1918 Frontier Airlines 6 2026-04-21
FFT1699 - 6 2026-07-18
FFT1668 - 6 2026-07-12
FFT1303 - 6 2026-07-12
FFT4506 - 5 2026-07-20
FFT4242 - 5 2026-07-19
FFT4118 Frontier Airlines 5 2026-07-26
FFT4107 Frontier Airlines 5 2026-07-18
FFT3975 Frontier Airlines 5 2026-05-29
FFT3581 Frontier Airlines 5 2026-07-18
FFT2715 Frontier Airlines 5 2026-04-19

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 FFT4118 MYR → CLE Jul 26, 21:05 UTCJul 26, 21:45 UTC40m
2026-07-26 FFT4117 CLE → MYR Jul 26, 18:30 UTCJul 26, 19:30 UTC1h 0m
2026-07-26 FFT2410 ATL → CLE Jul 26, 15:45 UTCJul 26, 17:05 UTC1h 20m
2026-07-26 FFT2467 CLE → ATL Jul 26, 13:10 UTCJul 26, 14:25 UTC1h 15m
2026-07-26 FFT1915 MCO → CLE Jul 26, 09:25 UTCJul 26, 11:35 UTC2h 10m
2026-07-26 FFT2451 CLT → MCO Jul 26, 00:20 UTCJul 26, 01:30 UTC1h 10m
2026-07-25 FFT3133 PHL → RDU Jul 25, 21:30 UTCJul 25, 22:50 UTC1h 20m
2026-07-25 FFT2432 TPA → CLE Jul 25, 17:20 UTCJul 25, 19:35 UTC2h 15m
2026-07-25 FFT3624 CVG → MCO Jul 25, 13:35 UTCJul 25, 15:15 UTC1h 40m
2026-07-25 FFT1565 MCO → CVG Jul 25, 10:13 UTCJul 25, 11:54 UTC1h 41m
2026-07-25 FFT1565 MCO → CVG Jul 25, 10:10 UTCJul 25, 11:45 UTC1h 35m
2026-07-25 FFT1612 CMH → MCO Jul 25, 01:15 UTCJul 25, 02:55 UTC1h 40m
2026-07-24 FFT2757 ONT → SFO Jul 24, 22:20 UTCJul 25, 00:15 UTC1h 55m
2026-07-24 FFT3476 RDU → PHL Jul 24, 18:10 UTCJul 24, 20:20 UTC2h 10m
2026-07-24 FFT1369 - Jul 24, 14:25 UTCJul 24, 16:40 UTC2h 15m
2026-07-24 FFT1612 CMH → MCO Jul 24, 01:00 UTCJul 24, 02:45 UTC1h 45m
2026-07-23 FFT2757 ONT → SFO Jul 23, 22:05 UTCJul 24, 00:00 UTC1h 55m
2026-07-23 FFT3312 DEN → MCO Jul 23, 16:55 UTCJul 23, 20:10 UTC3h 15m
2026-07-23 FFT1230 MCO → GRB Jul 23, 13:05 UTCJul 23, 15:05 UTC2h 0m
2026-07-23 FFT3439 DEN → SFO Jul 23, 05:55 UTCJul 23, 08:00 UTC2h 5m
2026-07-23 FFT3439 DEN → SFO Jul 23, 05:48 UTCJul 23, 07:58 UTC2h 10m
2026-07-23 FFT4625 MEM → DEN Jul 23, 02:30 UTCJul 23, 04:30 UTC2h 0m
2026-07-22 FFT4626 DEN → MEM Jul 22, 22:00 UTCJul 22, 23:45 UTC1h 45m
2026-07-22 FFT1401 - Jul 22, 17:15 UTCJul 22, 19:35 UTC2h 20m
2026-07-22 FFT1402 DEN → BNA Jul 22, 14:05 UTCJul 22, 16:10 UTC2h 5m
2026-07-22 FFT2147 - Jul 22, 11:10 UTCJul 22, 12:00 UTC50m
2026-07-22 FFT1523 ATL → SFO Jul 22, 03:11 UTCJul 22, 04:09 UTC58m
2026-07-22 FFT1523 ATL → SFO Jul 22, 02:55 UTCJul 22, 04:15 UTC1h 20m
2026-07-22 FFT1524 SFO → ATL Jul 22, 00:18 UTCJul 22, 01:23 UTC1h 5m
2026-07-22 FFT1524 SFO → ATL Jul 22, 00:10 UTCJul 22, 01:35 UTC1h 25m
2026-07-21 FFT2532 PHX → DFW Jul 21, 20:45 UTCJul 21, 22:45 UTC2h 0m
2026-07-21 FFT4655 DFW → PHX Jul 21, 17:05 UTCJul 21, 19:00 UTC1h 55m
2026-07-21 FFT3978 LAS → DFW Jul 21, 13:10 UTCJul 21, 15:30 UTC2h 20m
2026-07-21 FFT1326 SAN → LAS Jul 21, 04:40 UTCJul 21, 05:35 UTC55m
2026-07-21 FFT1469 LAS → SAN Jul 21, 02:30 UTCJul 21, 03:15 UTC45m
2026-07-20 FFT4505 MCI → LAS Jul 20, 22:30 UTCJul 21, 00:45 UTC2h 15m
2026-07-20 FFT4505 MCI → LAS Jul 20, 22:11 UTCJul 21, 00:44 UTC2h 33m
2026-07-20 FFT4506 - Jul 20, 18:05 UTCJul 20, 20:30 UTC2h 25m
2026-07-20 FFT2801 - Jul 20, 13:05 UTCJul 20, 16:40 UTC3h 35m
2026-07-20 FFT2802 DEN → MCO Jul 20, 07:15 UTCJul 20, 10:50 UTC3h 35m
2026-07-20 FFT1326 SAN → LAS Jul 20, 04:30 UTCJul 20, 05:25 UTC55m
2026-07-20 FFT1469 LAS → SAN Jul 20, 02:05 UTCJul 20, 02:50 UTC45m
2026-07-19 FFT4505 MCI → LAS Jul 19, 22:00 UTCJul 20, 00:15 UTC2h 15m
2026-07-19 FFT4506 - Jul 19, 18:10 UTCJul 19, 20:50 UTC2h 40m
2026-07-19 FFT4506 LAS → MCI Jul 19, 18:05 UTCJul 19, 20:46 UTC2h 41m
2026-07-19 FFT2801 - Jul 19, 12:50 UTCJul 19, 16:25 UTC3h 35m
2026-07-19 FFT2802 - Jul 19, 07:10 UTCJul 19, 10:45 UTC3h 35m
2026-07-19 FFT4242 - Jul 19, 03:45 UTCJul 19, 04:45 UTC1h 0m
2026-07-19 FFT4241 - Jul 19, 01:35 UTCJul 19, 02:30 UTC55m
2026-07-18 FFT4158 SFO → LAS Jul 18, 22:45 UTCJul 19, 00:00 UTC1h 15m

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 N236FR page for operator, model, and routing details .

Mode-S A21F57 frequently asked

What is Mode-S code A21F57?
A21F57 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N236FR.
Where is Mode-S A21F57 registered?
Mode-S code A21F57 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 A21F57 broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 21:45 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A21F57, octal 50417527, decimal 10,624,855.
What flights does A21F57 operate?
Mode-S A21F57 has broadcast 20 distinct callsigns, including FFT3091, FFT4639, FFT3092, FFT9436, FFT4685.