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 Jul 26, 22:15 UTC
Flights observed
529
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 22:15 UTC

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
FFT2021 Frontier Airlines 6 2026-07-22
FFT3978 - 5 2026-07-17
FFT3663 Frontier Airlines 5 2026-05-30
FFT3291 - 5 2026-07-18
FFT3231 - 5 2026-07-08
FFT2060 - 5 2026-07-11
FFT1954 Frontier Airlines 5 2026-05-13
FFT1647 Frontier Airlines 5 2026-07-18
FFT1601 Frontier Airlines 5 2026-07-23
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
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
FFT1620 Frontier Airlines 4 2026-05-14
FFT1602 Frontier Airlines 4 2026-07-20

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 FFT3108 LAS → STL Jul 26, 20:10 UTCJul 26, 22:15 UTC2h 5m
2026-07-26 FFT4277 IAD → LAS Jul 26, 13:55 UTCJul 26, 18:05 UTC4h 10m
2026-07-26 FFT4278 SAN → DFW Jul 26, 08:15 UTCJul 26, 12:15 UTC4h 0m
2026-07-26 FFT1821 CLE → LAS Jul 26, 01:50 UTCJul 26, 05:35 UTC3h 45m
2026-07-25 FFT1545 PHL → TPA Jul 25, 02:30 UTCJul 25, 04:50 UTC2h 20m
2026-07-25 FFT1545 PHL → TPA Jul 25, 01:37 UTCJul 25, 04:59 UTC3h 22m
2026-07-24 FFT1544 CLE → RSW Jul 24, 22:15 UTCJul 25, 00:35 UTC2h 20m
2026-07-24 FFT206 CUN → CLE Jul 24, 15:55 UTCJul 24, 18:55 UTC3h 0m
2026-07-24 FFT207 CLE → CUN Jul 24, 11:30 UTCJul 24, 14:30 UTC3h 0m
2026-07-23 FFT3232 LAS → CLE Jul 23, 22:55 UTCJul 24, 02:40 UTC3h 45m
2026-07-23 FFT1601 PHL → MCO Jul 23, 16:20 UTCJul 23, 21:10 UTC4h 50m
2026-07-23 FFT1601 PHL → MCO Jul 23, 16:01 UTCJul 23, 21:09 UTC5h 8m
2026-07-23 FFT9421 MSP → DEN Jul 23, 01:35 UTCJul 23, 02:40 UTC1h 5m
2026-07-22 FFT2021 PHL → DTW Jul 22, 11:10 UTCJul 22, 12:00 UTC50m
2026-07-22 FFT2021 PHL → DTW Jul 22, 10:42 UTCJul 22, 11:52 UTC1h 10m
2026-07-22 FFT1101 PHL → ATL Jul 22, 01:45 UTCJul 22, 03:35 UTC1h 50m
2026-07-21 FFT23 PUJ → PHL Jul 21, 16:06 UTCJul 21, 19:42 UTC3h 36m
2026-07-21 FFT22 PHL → PUJ Jul 21, 11:05 UTCJul 21, 12:00 UTC55m
2026-07-21 FFT1328 CLT → PHL Jul 21, 05:25 UTCJul 21, 06:25 UTC1h 0m
2026-07-21 FFT1984 FLL → ISP Jul 21, 02:30 UTCJul 21, 04:05 UTC1h 35m
2026-07-20 FFT4455 PHL → FLL Jul 20, 22:55 UTCJul 21, 01:15 UTC2h 19m
2026-07-20 FFT4455 PHL → FLL Jul 20, 22:30 UTCJul 20, 22:35 UTC5m
2026-07-20 FFT3856 MCO → PHL Jul 20, 17:30 UTCJul 20, 19:40 UTC2h 10m
2026-07-20 FFT3856 MCO → PHL Jul 20, 17:13 UTCJul 20, 19:36 UTC2h 23m
2026-07-20 FFT1807 - Jul 20, 13:35 UTCJul 20, 15:35 UTC2h 0m
2026-07-20 FFT1807 PHL → PHL Jul 20, 13:20 UTCJul 20, 13:25 UTC5m
2026-07-20 FFT1602 SNA → LAS Jul 20, 06:55 UTCJul 20, 11:25 UTC4h 30m
2026-07-19 FFT3450 LAS → LAS Jul 19, 23:45 UTCJul 20, 03:30 UTC3h 45m
2026-07-19 FFT4131 - Jul 19, 18:40 UTCJul 19, 21:15 UTC2h 35m
2026-07-19 FFT1490 - Jul 19, 14:25 UTCJul 19, 17:05 UTC2h 40m
2026-07-19 FFT4156 SFO → LAS Jul 19, 05:30 UTCJul 19, 06:30 UTC1h 0m
2026-07-19 FFT4156 SFO → LAS Jul 19, 05:33 UTCJul 19, 06:34 UTC1h 1m
2026-07-19 FFT3801 LAS → SFO Jul 19, 03:10 UTCJul 19, 04:25 UTC1h 15m
2026-07-18 FFT2575 SLC → LAS Jul 18, 21:50 UTCJul 18, 22:45 UTC55m
2026-07-18 FFT1268 LAX → SLC Jul 18, 19:10 UTCJul 18, 20:35 UTC1h 25m
2026-07-18 FFT1268 LAX → SLC Jul 18, 19:16 UTCJul 18, 20:34 UTC1h 18m
2026-07-18 FFT3291 - Jul 18, 17:25 UTCJul 18, 18:05 UTC40m
2026-07-18 FFT1647 DFW → LAS Jul 18, 02:55 UTCJul 18, 05:10 UTC2h 15m
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

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 Jul 26, 22:15 UTC.
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 FFT2021, FFT3978, FFT3663, FFT3291, FFT3231.