Apparatus

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sensors Mode-S transponder

A539F5

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N436FR · AIRBUS A-320neo · operated by FRONTIER AIRLINES INC.

Hex
A539F5
Octal
51234765
Decimal
10,828,277
Country
US
Tail
N436FR
Type
A20N
No current signal · last broadcast 3h ago
Flights observed
505
Distinct callsigns
20
Country
US
Last broadcast
3h ago

Last known position

Most recent position reported by Mode-S A539F5.

Country allocation

The ICAO 24-bit address A539F5 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
FFT2695 Frontier Airlines 9 2026-06-10
FFT2836 Frontier Airlines 8 2026-05-31
FFT3224 - 7 2026-07-01
FFT2269 Frontier Airlines 7 2026-06-01
FFT1984 Frontier Airlines 7 2026-06-12
FFT1726 Frontier Airlines 7 2026-06-08
FFT1225 Frontier Airlines 7 2026-06-09
FFT1016 Frontier Airlines 7 2026-06-08
FFT4353 Frontier Airlines 6 2026-06-11
FFT2835 - 6 2026-06-14
FFT2388 Frontier Airlines 6 2026-06-12
FFT1983 Frontier Airlines 6 2026-06-12
FFT1003 Frontier Airlines 6 2026-05-16
FFT685 Frontier Airlines 5 2026-04-14
FFT3223 - 5 2026-07-01
FFT3021 - 5 2026-07-01
FFT1270 - 5 2026-07-01
FFT1102 - 5 2026-06-13
FFT4000 - 4 2026-07-02
FFT3999 - 4 2026-07-02

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-14 FFT1068 - Jul 14, 03:20 UTCJul 14, 05:25 UTC2h 5m
2026-07-13 FFT2395 - Jul 13, 23:15 UTCJul 14, 01:45 UTC2h 30m
2026-07-13 FFT3037 - Jul 13, 19:00 UTCJul 13, 20:30 UTC1h 30m
2026-07-13 FFT3037 MIA → CLT Jul 13, 19:06 UTCJul 13, 20:29 UTC1h 23m
2026-07-13 FFT4406 ATL → MIA Jul 13, 16:00 UTCJul 13, 17:25 UTC1h 25m
2026-07-13 FFT2483 - Jul 13, 12:45 UTCJul 13, 14:10 UTC1h 25m
2026-07-13 FFT2483 MIA → ATL Jul 13, 12:43 UTCJul 13, 14:06 UTC1h 23m
2026-07-13 FFT4552 - Jul 13, 05:55 UTCJul 13, 10:10 UTC4h 15m
2026-07-13 FFT3891 OKC → LAS Jul 13, 01:05 UTCJul 13, 03:05 UTC2h 0m
2026-07-12 FFT1992 LAS → OKC Jul 12, 21:40 UTCJul 12, 23:50 UTC2h 10m
2026-07-12 FFT2232 POC → LAS Jul 12, 18:50 UTCJul 12, 19:45 UTC55m
2026-07-12 FFT2678 SFO → ONT Jul 12, 16:45 UTCJul 12, 17:50 UTC1h 5m
2026-07-12 FFT3019 LAS → SFO Jul 12, 14:35 UTCJul 12, 15:45 UTC1h 10m
2026-07-12 FFT3885 DFW → LAS Jul 12, 04:15 UTCJul 12, 06:25 UTC2h 10m
2026-07-12 FFT2999 - Jul 12, 00:35 UTCJul 12, 02:40 UTC2h 5m
2026-07-11 FFT2882 DFW → MDW Jul 11, 20:15 UTCJul 11, 22:05 UTC1h 50m
2026-07-11 FFT3366 DEN → DFW Jul 11, 16:25 UTCJul 11, 17:50 UTC1h 25m
2026-07-11 FFT1500 - Jul 11, 13:00 UTCJul 11, 13:15 UTC15m
2026-07-11 FFT1500 ONT → DEN Jul 11, 13:13 UTCJul 11, 14:50 UTC1h 37m
2026-07-11 FFT1261 DEN → ONT Jul 11, 05:40 UTCJul 11, 07:25 UTC1h 45m
2026-07-11 FFT1261 DEN → ONT Jul 11, 05:45 UTCJul 11, 07:24 UTC1h 39m
2026-07-11 FFT4567 STL → DEN Jul 11, 02:15 UTCJul 11, 04:05 UTC1h 50m
2026-07-10 FFT3302 DEN → STL Jul 10, 22:15 UTCJul 10, 23:50 UTC1h 35m
2026-07-10 FFT1677 DSM → DEN Jul 10, 19:27 UTCJul 10, 20:53 UTC1h 26m
2026-07-10 FFT1678 DEN → DSM Jul 10, 17:00 UTCJul 10, 18:15 UTC1h 15m
2026-07-10 FFT1678 DEN → DSM Jul 10, 16:58 UTCJul 10, 18:13 UTC1h 15m
2026-07-10 FFT1230 SFO → DEN Jul 10, 13:15 UTCJul 10, 15:15 UTC2h 0m
2026-07-10 FFT3439 DEN → SFO Jul 10, 04:45 UTCJul 10, 07:05 UTC2h 20m
2026-07-10 FFT4346 - Jul 10, 00:55 UTCJul 10, 02:45 UTC1h 50m
2026-07-09 FFT2341 - Jul 9, 21:30 UTCJul 9, 23:30 UTC2h 0m
2026-07-09 FFT3565 - Jul 9, 17:20 UTCJul 9, 19:55 UTC2h 35m
2026-07-09 FFT3566 DEN → DTW Jul 9, 13:54 UTCJul 9, 15:54 UTC2h 0m
2026-07-09 FFT3566 DEN → DTW Jul 9, 13:45 UTCJul 9, 15:55 UTC2h 10m
2026-07-09 FFT4069 DFW → DEN Jul 9, 04:25 UTCJul 9, 06:00 UTC1h 35m
2026-07-09 FFT2148 DEN → DFW Jul 9, 00:40 UTCJul 9, 02:05 UTC1h 25m
2026-07-08 FFT2148 DEN → DFW Jul 8, 23:50 UTCJul 9, 02:05 UTC2h 15m
2026-07-08 FFT4768 PHX → DEN Jul 8, 20:40 UTCJul 8, 22:35 UTC1h 55m
2026-07-08 FFT2697 - Jul 8, 01:15 UTCJul 8, 04:45 UTC3h 30m
2026-07-07 FFT2698 PHX → CLE Jul 7, 19:50 UTCJul 7, 23:30 UTC3h 40m
2026-07-06 FFT2607 ATL → PHX Jul 6, 23:35 UTCJul 7, 03:00 UTC3h 25m
2026-07-06 FFT2607 ATL → PHX Jul 6, 23:15 UTCJul 7, 02:52 UTC3h 37m
2026-07-06 FFT4702 - Jul 6, 20:10 UTCJul 6, 21:55 UTC1h 45m
2026-07-06 FFT4211 ATL → AUS Jul 6, 17:10 UTCJul 6, 19:00 UTC1h 50m
2026-07-06 FFT2483 - Jul 6, 12:55 UTCJul 6, 14:20 UTC1h 25m
2026-07-06 FFT4552 - Jul 6, 05:45 UTCJul 6, 10:00 UTC4h 15m
2026-07-06 FFT1106 - Jul 6, 02:00 UTCJul 6, 03:55 UTC1h 55m
2026-07-05 FFT1105 - Jul 5, 22:50 UTCJul 6, 00:40 UTC1h 50m
2026-07-05 FFT1105 LAS → PDX Jul 5, 22:51 UTCJul 6, 00:35 UTC1h 44m
2026-07-05 FFT2575 SLC → LAS Jul 5, 20:15 UTCJul 5, 21:15 UTC1h 0m
2026-07-05 FFT1268 LAX → SLC Jul 5, 17:30 UTCJul 5, 18:55 UTC1h 25m

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 N436FR page for operator, model, and routing details .

Mode-S A539F5 frequently asked

What is Mode-S code A539F5?
A539F5 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N436FR.
Where is Mode-S A539F5 registered?
Mode-S code A539F5 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 A539F5 broadcasting right now?
No active broadcast right now. Last signal was 3h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A539F5, octal 51234765, decimal 10,828,277.
What flights does A539F5 operate?
Mode-S A539F5 has broadcast 20 distinct callsigns, including FFT2695, FFT2836, FFT3224, FFT2269, FFT1984.