Apparatus

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sensors Mode-S transponder

A21BA0

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N235FR · AIRBUS A-320 · operated by UMB BANK NA TRUSTEE

Hex
A21BA0
Octal
50415640
Decimal
10,623,904
Country
US
Tail
N235FR
Type
A320
Transponder active on ground
Flights observed
342
Distinct callsigns
20
Country
US
Last broadcast
24m ago

Last known position

Most recent position reported by Mode-S A21BA0.

Country allocation

The ICAO 24-bit address A21BA0 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
FFT4371 - 6 2026-07-02
FFT3412 Frontier Airlines 6 2026-04-17
FFT9435 - 5 2026-07-12
FFT4372 - 5 2026-07-02
FFT3981 - 5 2026-06-22
FFT1750 Frontier Airlines 5 2026-04-19
FFT687 - 4 2026-06-29
FFT3326 Frontier Airlines 4 2026-06-18
FFT3277 - 4 2026-06-25
FFT2908 Frontier Airlines 4 2026-06-04
FFT2615 Frontier Airlines 4 2026-05-20
FFT2147 - 4 2026-07-04
FFT1874 - 4 2026-06-29
FFT1749 Frontier Airlines 4 2026-04-16
FFT1713 Frontier Airlines 4 2026-04-17
FFT1127 - 4 2026-06-30
FFT690 Frontier Airlines 3 2026-07-07
FFT686 - 3 2026-06-29
FFT685 - 3 2026-07-08
FFT4559 - 3 2026-06-20

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-14 FFT4671 - Jul 14, 01:00 UTCJul 14, 04:00 UTC3h 0m
2026-07-13 FFT1958 - Jul 13, 20:45 UTCJul 13, 23:25 UTC2h 40m
2026-07-13 FFT4184 PHX → IAH Jul 13, 16:17 UTCJul 13, 18:46 UTC2h 29m
2026-07-13 FFT4184 - Jul 13, 16:25 UTCJul 13, 18:50 UTC2h 25m
2026-07-13 FFT2638 - Jul 13, 03:10 UTCJul 13, 04:50 UTC1h 40m
2026-07-12 FFT3393 SLC → SFO Jul 12, 23:55 UTCJul 13, 01:35 UTC1h 40m
2026-07-12 FFT2526 PHX → SLC Jul 12, 21:25 UTCJul 12, 22:35 UTC1h 10m
2026-07-12 FFT3971 DFW → PHX Jul 12, 18:10 UTCJul 12, 20:05 UTC1h 55m
2026-07-12 FFT2532 PHX → DFW Jul 12, 14:50 UTCJul 12, 16:55 UTC2h 5m
2026-07-12 FFT9435 SLC → PHX Jul 12, 06:52 UTCJul 12, 07:36 UTC44m
2026-07-12 FFT9435 - Jul 12, 06:25 UTCJul 12, 06:35 UTC10m
2026-07-09 FFT2526 PHX → SLC Jul 9, 20:50 UTCJul 9, 22:05 UTC1h 15m
2026-07-09 FFT3971 DFW → PHX Jul 9, 17:40 UTCJul 9, 19:30 UTC1h 50m
2026-07-08 FFT3175 - Jul 8, 23:30 UTCJul 9, 01:40 UTC2h 10m
2026-07-08 FFT3990 SAN → DFW Jul 8, 19:40 UTCJul 8, 21:55 UTC2h 15m
2026-07-08 FFT3366 DEN → DFW Jul 8, 16:20 UTCJul 8, 17:50 UTC1h 30m
2026-07-08 FFT685 - Jul 8, 11:50 UTCJul 8, 15:00 UTC3h 10m
2026-07-07 FFT690 DEN → DCA Jul 7, 22:55 UTCJul 8, 02:00 UTC3h 5m
2026-07-07 FFT1091 IND → MCO Jul 7, 19:30 UTCJul 7, 20:55 UTC1h 25m
2026-07-07 FFT4344 - Jul 7, 16:55 UTCJul 7, 18:15 UTC1h 20m
2026-07-07 FFT4344 DEN → XNA Jul 7, 17:00 UTCJul 7, 18:13 UTC1h 13m
2026-07-07 FFT4069 DFW → DEN Jul 7, 03:25 UTCJul 7, 05:00 UTC1h 35m
2026-07-06 FFT2148 - Jul 6, 23:40 UTCJul 7, 00:00 UTC20m
2026-07-06 FFT2148 DEN → DFW Jul 6, 23:36 UTCJul 7, 01:03 UTC1h 27m
2026-07-06 FFT1863 OKC → DEN Jul 6, 21:05 UTCJul 6, 22:25 UTC1h 20m
2026-07-06 FFT1928 DEN → OKC Jul 6, 18:45 UTCJul 6, 19:55 UTC1h 10m
2026-07-06 FFT4768 - Jul 6, 15:50 UTCJul 6, 17:10 UTC1h 20m
2026-07-06 FFT1747 - Jul 6, 12:55 UTCJul 6, 14:25 UTC1h 30m
2026-07-06 FFT4946 - Jul 6, 04:10 UTCJul 6, 06:00 UTC1h 50m
2026-07-06 FFT4500 - Jul 6, 00:40 UTCJul 6, 02:40 UTC2h 0m
2026-07-05 FFT2553 DEN → PDX Jul 5, 21:10 UTCJul 5, 23:30 UTC2h 20m
2026-07-05 FFT3293 ATL → DEN Jul 5, 16:40 UTCJul 5, 19:10 UTC2h 30m
2026-07-05 FFT3294 DEN → ATL Jul 5, 12:35 UTCJul 5, 15:05 UTC2h 30m
2026-07-05 FFT3294 DEN → ATL Jul 5, 12:43 UTCJul 5, 15:00 UTC2h 17m
2026-07-04 FFT3565 - Jul 4, 17:30 UTCJul 4, 20:00 UTC2h 30m
2026-07-04 FFT3566 DEN → DTW Jul 4, 13:55 UTCJul 4, 16:20 UTC2h 25m
2026-07-04 FFT3566 DEN → DTW Jul 4, 14:03 UTCJul 4, 16:19 UTC2h 16m
2026-07-04 FFT2147 - Jul 4, 10:30 UTCJul 4, 12:05 UTC1h 35m
2026-07-04 FFT2632 DEN → DFW Jul 4, 02:50 UTCJul 4, 04:20 UTC1h 30m
2026-07-03 FFT2631 DFW → DEN Jul 3, 23:30 UTCJul 4, 01:35 UTC2h 5m
2026-07-03 FFT2471 EWR → DFW Jul 3, 18:45 UTCJul 3, 21:50 UTC3h 5m
2026-07-03 FFT2472 DFW → EWR Jul 3, 13:25 UTCJul 3, 16:45 UTC3h 20m
2026-07-03 FFT2632 DEN → DFW Jul 3, 03:00 UTCJul 3, 04:30 UTC1h 30m
2026-07-02 FFT4236 SLC → DEN Jul 2, 23:35 UTCJul 3, 01:00 UTC1h 25m
2026-07-02 FFT3861 DEN → SLC Jul 2, 21:05 UTCJul 2, 22:05 UTC1h 0m
2026-07-02 FFT4372 - Jul 2, 17:20 UTCJul 2, 19:05 UTC1h 45m
2026-07-02 FFT4371 - Jul 2, 14:05 UTCJul 2, 16:05 UTC2h 0m
2026-06-30 FFT1127 - Jun 30, 01:30 UTCJun 30, 02:45 UTC1h 15m
2026-06-29 FFT1874 - Jun 29, 23:19 UTCJun 30, 00:20 UTC1h 0m
2026-06-29 FFT687 DCA → DEN Jun 29, 18:13 UTCJun 29, 21:57 UTC3h 44m

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 N235FR page for operator, model, and routing details .

Mode-S A21BA0 frequently asked

What is Mode-S code A21BA0?
A21BA0 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N235FR.
Where is Mode-S A21BA0 registered?
Mode-S code A21BA0 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 A21BA0 broadcasting right now?
Mode-S A21BA0 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 A21BA0, octal 50415640, decimal 10,623,904.
What flights does A21BA0 operate?
Mode-S A21BA0 has broadcast 20 distinct callsigns, including FFT4371, FFT3412, FFT9435, FFT4372, FFT3981.