Apparatus

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sensors Mode-S transponder

A81A81

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N621FR · AIRBUS A-321neo · operated by BANK OF UTAH TRUSTEE

Hex
A81A81
Octal
52015201
Decimal
11,016,833
Country
US
Tail
N621FR
Type
A21N
No current signal · last broadcast 2h ago
Flights observed
492
Distinct callsigns
20
Country
US
Last broadcast
2h ago

Last known position

Most recent position reported by Mode-S A81A81.

Country allocation

The ICAO 24-bit address A81A81 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
FFT3978 - 5 2026-07-17
FFT3663 Frontier Airlines 5 2026-05-30
FFT3231 - 5 2026-07-08
FFT2060 - 5 2026-07-11
FFT1954 Frontier Airlines 5 2026-05-13
FFT1647 Frontier Airlines 5 2026-07-18
FFT71 Frontier Airlines 4 2026-06-14
FFT67 - 4 2026-06-30
FFT4966 Frontier Airlines 4 2026-07-08
FFT4797 Frontier Airlines 4 2026-06-09
FFT3778 - 4 2026-07-16
FFT3291 Frontier Airlines 4 2026-04-26
FFT3227 Frontier Airlines 4 2026-06-26
FFT3206 Frontier Airlines 4 2026-06-14
FFT2356 Frontier Airlines 4 2026-06-21
FFT2341 - 4 2026-07-02
FFT2021 - 4 2026-07-11
FFT1620 Frontier Airlines 4 2026-05-14
FFT1229 - 4 2026-07-01
FFT1094 - 4 2026-07-01

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-18 FFT1647 DFW → LAS Jul 18, 02:55 UTCJul 18, 04:15 UTC1h 20m
2026-07-17 FFT1052 - Jul 17, 22:10 UTCJul 18, 00:55 UTC2h 45m
2026-07-17 FFT1051 - Jul 17, 17:40 UTCJul 17, 20:04 UTC2h 25m
2026-07-17 FFT3978 LAS → DFW Jul 17, 13:10 UTCJul 17, 15:25 UTC2h 15m
2026-07-17 FFT2334 - Jul 17, 05:55 UTCJul 17, 06:54 UTC1h 0m
2026-07-17 FFT2333 - Jul 17, 02:15 UTCJul 17, 02:54 UTC40m
2026-07-16 FFT3777 BNA → LAS Jul 16, 21:10 UTCJul 17, 00:25 UTC3h 15m
2026-07-16 FFT3778 LAS → BNA Jul 16, 16:19 UTCJul 16, 19:45 UTC3h 25m
2026-07-16 FFT1184 LAX → LAS Jul 16, 13:40 UTCJul 16, 14:29 UTC50m
2026-07-16 FFT1184 LAX → LAS Jul 16, 13:42 UTCJul 16, 14:26 UTC44m
2026-07-16 FFT2445 - Jul 16, 03:45 UTCJul 16, 07:10 UTC3h 25m
2026-07-16 FFT3397 ATL → ORD Jul 16, 00:35 UTCJul 16, 02:00 UTC1h 25m
2026-07-15 FFT2198 - Jul 15, 20:10 UTCJul 15, 21:40 UTC1h 30m
2026-07-15 FFT2206 FLL → ORD Jul 15, 14:45 UTCJul 15, 17:25 UTC2h 40m
2026-07-15 FFT3017 SJU → FLL Jul 15, 10:45 UTCJul 15, 13:10 UTC2h 25m
2026-07-15 FFT4462 PHL → SJU Jul 15, 01:05 UTCJul 15, 04:20 UTC3h 15m
2026-07-14 FFT181 PHL → PHL Jul 14, 11:45 UTCJul 14, 20:10 UTC8h 25m
2026-07-14 FFT1328 - Jul 14, 02:55 UTCJul 14, 04:05 UTC1h 10m
2026-07-13 FFT1984 - Jul 13, 23:40 UTCJul 14, 01:20 UTC1h 40m
2026-07-13 FFT4455 PHL → FLL Jul 13, 19:20 UTCJul 13, 21:40 UTC2h 20m
2026-07-13 FFT2112 - Jul 13, 03:30 UTCJul 13, 04:45 UTC1h 15m
2026-07-12 FFT2111 PHL → ORD Jul 12, 22:15 UTCJul 13, 00:30 UTC2h 15m
2026-07-12 FFT2111 PHL → ORD Jul 12, 22:21 UTCJul 13, 00:22 UTC2h 1m
2026-07-12 FFT357 STI → PHL Jul 12, 17:50 UTCJul 12, 18:45 UTC55m
2026-07-12 FFT357 STI → PHL Jul 12, 15:28 UTCJul 12, 18:42 UTC3h 14m
2026-07-12 FFT356 - Jul 12, 10:50 UTCJul 12, 12:35 UTC1h 45m
2026-07-12 FFT356 PHL → STI Jul 12, 10:36 UTCJul 12, 14:07 UTC3h 31m
2026-07-12 - - Jul 12, 04:50 UTCJul 12, 04:55 UTC5m
2026-07-12 FFT4844 - Jul 12, 02:01 UTCJul 12, 03:01 UTC1h 0m
2026-07-12 FFT4844 RDU → PHL Jul 12, 02:10 UTCJul 12, 02:52 UTC42m
2026-07-11 FFT1517 PHL → RDU Jul 11, 23:55 UTCJul 12, 00:50 UTC55m
2026-07-11 FFT2932 - Jul 11, 17:55 UTCJul 11, 20:05 UTC2h 10m
2026-07-11 FFT2007 - Jul 11, 13:30 UTCJul 11, 16:05 UTC2h 35m
2026-07-11 FFT2021 - Jul 11, 10:40 UTCJul 11, 11:55 UTC1h 15m
2026-07-11 FFT2021 PHL → PHL Jul 11, 10:20 UTCJul 11, 10:35 UTC15m
2026-07-11 FFT2021 PHL → PHL Jul 11, 09:55 UTCJul 11, 10:00 UTC5m
2026-07-11 FFT2021 PHL → PHL Jul 11, 09:40 UTCJul 11, 09:45 UTC5m
2026-07-11 FFT2060 PHL → PHL Jul 11, 06:35 UTCJul 11, 06:45 UTC10m
2026-07-11 FFT2060 PHL → PHL Jul 11, 06:01 UTCJul 11, 06:05 UTC5m
2026-07-11 FFT2060 PHL → PHL Jul 11, 05:31 UTCJul 11, 05:40 UTC10m
2026-07-11 FFT2060 PHL → PHL Jul 11, 04:25 UTCJul 11, 04:30 UTC5m
2026-07-10 FFT2060 RDU → PHL Jul 10, 21:55 UTCJul 10, 22:50 UTC55m
2026-07-10 FFT2730 TPA → RDU Jul 10, 19:00 UTCJul 10, 20:30 UTC1h 30m
2026-07-10 FFT4807 JAX → TPA Jul 10, 16:55 UTCJul 10, 17:35 UTC40m
2026-07-10 FFT4807 - Jul 10, 13:40 UTCJul 10, 15:35 UTC1h 55m
2026-07-10 FFT1602 - Jul 10, 06:05 UTCJul 10, 10:15 UTC4h 10m
2026-07-10 FFT1647 DFW → LAS Jul 10, 02:15 UTCJul 10, 04:35 UTC2h 20m
2026-07-09 FFT1052 LAS → DFW Jul 9, 21:40 UTCJul 10, 00:15 UTC2h 35m
2026-07-09 FFT1051 DFW → LAS Jul 9, 17:25 UTCJul 9, 19:40 UTC2h 15m
2026-07-09 FFT3978 LAS → DFW Jul 9, 13:10 UTCJul 9, 15:30 UTC2h 20m

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 N621FR page for operator, model, and routing details .

Mode-S A81A81 frequently asked

What is Mode-S code A81A81?
A81A81 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N621FR.
Where is Mode-S A81A81 registered?
Mode-S code A81A81 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 A81A81 broadcasting right now?
No active broadcast right now. Last signal was 2h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A81A81, octal 52015201, decimal 11,016,833.
What flights does A81A81 operate?
Mode-S A81A81 has broadcast 20 distinct callsigns, including FFT3978, FFT3663, FFT3231, FFT2060, FFT1954.