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
Broadcasting now · callsign FFT2144 · 36,975 ft
Flights observed
568
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 20:35 UTC

Current position

A539F5 is currently broadcasting. Map zoomed to live position.

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
FFT3566 Frontier Airlines 5 2026-07-25
FFT3223 - 5 2026-07-01
FFT3021 - 5 2026-07-01
FFT2348 Frontier Airlines 5 2026-07-25
FFT2347 Frontier Airlines 5 2026-07-26
FFT1270 - 5 2026-07-01

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 FFT2513 GRR → TPA Jul 26, 17:10 UTCJul 26, 20:35 UTC3h 25m
2026-07-26 FFT2514 DEN → PHL Jul 26, 12:40 UTCJul 26, 15:35 UTC2h 55m
2026-07-26 FFT2347 PHL → PBI Jul 26, 01:00 UTCJul 26, 03:10 UTC2h 10m
2026-07-25 FFT2348 PBI → PHL Jul 25, 21:40 UTCJul 25, 23:40 UTC2h 0m
2026-07-25 FFT3565 DTW → DEN Jul 25, 17:30 UTCJul 25, 20:00 UTC2h 30m
2026-07-25 FFT3565 DTW → DEN Jul 25, 17:30 UTCJul 25, 19:54 UTC2h 24m
2026-07-25 FFT3566 DEN → DTW Jul 25, 13:50 UTCJul 25, 16:00 UTC2h 10m
2026-07-25 FFT1247 GRR → DEN Jul 25, 00:40 UTCJul 25, 03:00 UTC2h 20m
2026-07-24 FFT1248 DEN → GRR Jul 24, 21:30 UTCJul 24, 23:35 UTC2h 5m
2026-07-24 FFT1401 BNA → DEN Jul 24, 17:40 UTCJul 24, 20:10 UTC2h 30m
2026-07-24 FFT1402 DEN → BNA Jul 24, 14:10 UTCJul 24, 16:25 UTC2h 15m
2026-07-24 FFT2745 TPA → DEN Jul 24, 01:30 UTCJul 24, 05:15 UTC3h 45m
2026-07-23 FFT1689 PWM → RDU Jul 23, 21:45 UTCJul 24, 00:10 UTC2h 25m
2026-07-23 FFT1690 RDU → PWM Jul 23, 17:45 UTCJul 23, 20:35 UTC2h 50m
2026-07-23 FFT3782 DTW → ATL Jul 23, 15:25 UTCJul 23, 16:25 UTC1h 0m
2026-07-23 FFT1853 TPA → ATL Jul 23, 11:20 UTCJul 23, 12:35 UTC1h 15m
2026-07-23 FFT2912 ATL → TPA Jul 23, 03:20 UTCJul 23, 04:20 UTC1h 0m
2026-07-22 FFT4435 TPA → ATL Jul 22, 21:00 UTCJul 22, 22:00 UTC1h 0m
2026-07-22 FFT1689 PWM → RDU Jul 22, 17:20 UTCJul 22, 19:50 UTC2h 30m
2026-07-21 FFT1690 RDU → PWM Jul 21, 17:10 UTCJul 21, 19:30 UTC2h 20m
2026-07-21 FFT3782 DTW → ATL Jul 21, 14:45 UTCJul 21, 15:45 UTC1h 0m
2026-07-21 FFT4873 FLL → ATL Jul 21, 10:20 UTCJul 21, 11:45 UTC1h 25m
2026-07-21 FFT4873 FLL → ATL Jul 21, 10:21 UTCJul 21, 11:40 UTC1h 19m
2026-07-21 FFT2174 ATL → FLL Jul 21, 03:10 UTCJul 21, 04:30 UTC1h 20m
2026-07-20 FFT3500 - Jul 20, 23:15 UTCJul 21, 00:50 UTC1h 34m
2026-07-20 FFT3500 MCI → ATL Jul 20, 23:18 UTCJul 21, 00:49 UTC1h 31m
2026-07-20 FFT3499 - Jul 20, 20:10 UTCJul 20, 21:50 UTC1h 40m
2026-07-20 FFT3511 BOS → ATL Jul 20, 16:15 UTCJul 20, 18:20 UTC2h 5m
2026-07-20 FFT3058 RDU → BOS Jul 20, 13:05 UTCJul 20, 14:35 UTC1h 30m
2026-07-20 FFT1168 ATL → RDU Jul 20, 10:40 UTCJul 20, 11:45 UTC1h 5m
2026-07-19 FFT1123 - Jul 19, 23:20 UTCJul 20, 00:45 UTC1h 25m
2026-07-19 FFT2177 - Jul 19, 18:05 UTCJul 19, 19:40 UTC1h 35m
2026-07-19 FFT1951 MCO → DFW Jul 19, 14:00 UTCJul 19, 16:20 UTC2h 20m
2026-07-19 FFT1951 MCO → DFW Jul 19, 02:00 UTCJul 19, 04:10 UTC2h 10m
2026-07-18 FFT1952 - Jul 18, 22:10 UTCJul 19, 00:30 UTC2h 20m
2026-07-18 FFT1952 DFW → MCO Jul 18, 22:10 UTCJul 19, 00:30 UTC2h 20m
2026-07-18 FFT2343 RDU → ATL Jul 18, 18:05 UTCJul 18, 20:25 UTC2h 20m
2026-07-18 FFT3330 DFW → RDU Jul 18, 14:25 UTCJul 18, 16:50 UTC2h 25m
2026-07-18 FFT1650 LAS → DFW Jul 18, 09:40 UTCJul 18, 12:00 UTC2h 20m
2026-07-18 FFT3885 DFW → LAS Jul 18, 05:55 UTCJul 18, 08:10 UTC2h 15m
2026-07-18 FFT1757 CVG → TPA Jul 18, 00:00 UTCJul 18, 01:54 UTC1h 55m
2026-07-17 FFT4280 DFW → CVG Jul 17, 20:15 UTCJul 17, 22:00 UTC1h 45m
2026-07-17 FFT3177 - Jul 17, 15:55 UTCJul 17, 18:10 UTC2h 15m
2026-07-17 FFT3178 DFW → DTW Jul 17, 12:40 UTCJul 17, 14:50 UTC2h 10m
2026-07-17 FFT1887 MDW → DFW Jul 17, 03:55 UTCJul 17, 05:45 UTC1h 50m
2026-07-17 FFT2882 DFW → MDW Jul 17, 00:35 UTCJul 17, 02:39 UTC2h 5m
2026-07-16 FFT3787 - Jul 16, 20:05 UTCJul 16, 22:49 UTC2h 45m
2026-07-16 FFT3787 BWI → DFW Jul 16, 19:57 UTCJul 16, 22:49 UTC2h 52m
2026-07-16 FFT3788 - Jul 16, 16:15 UTCJul 16, 18:55 UTC2h 40m
2026-07-16 FFT1650 LAS → DFW Jul 16, 12:25 UTCJul 16, 14:55 UTC2h 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 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?
Yes. Mode-S A539F5 is currently airborne.
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.