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sensors Mode-S transponder

A1F5FF

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N2250U · BOEING 777-300ER · operated by UNITED AIRLINES INC

Hex
A1F5FF
Octal
50372777
Decimal
10,614,271
Country
US
Tail
N2250U
Type
B77W
No current signal · last broadcast Jul 26, 19:10 UTC
Flights observed
264
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 19:10 UTC

Last known position

Most recent position reported by Mode-S A1F5FF.

Country allocation

The ICAO 24-bit address A1F5FF 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
UAL1175 - 14 2026-07-07
UAL950 - 12 2026-07-13
UAL951 - 11 2026-07-14
UAL201 - 11 2026-07-08
UAL190 - 11 2026-07-07
UAL989 - 10 2026-07-14
UAL988 - 10 2026-07-13
UAL877 - 10 2026-06-29
UAL862 - 10 2026-06-30
UAL43 - 10 2026-07-15
UAL42 - 10 2026-07-13
UAL189 - 10 2026-07-06
UAL878 United Airlines 9 2026-07-25
UAL872 United Airlines 9 2026-07-21
UAL1844 - 9 2026-07-16
UAL869 United Airlines 8 2026-07-25
UAL200 - 8 2026-07-09
UAL871 - 7 2026-07-20
UAL79 United Airlines 7 2026-07-23
UAL435 - 7 2026-07-12

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL1960 MCO → ORD Jul 26, 14:00 UTCJul 26, 19:00 UTC5h 0m
2026-07-26 UAL2416 LAS → SFO Jul 26, 07:30 UTCJul 26, 12:05 UTC4h 35m
2026-07-25 UAL878 HKG → SFO Jul 25, 16:55 UTCJul 26, 03:20 UTC10h 25m
2026-07-25 UAL878 HKG → SFO Jul 25, 14:50 UTCJul 25, 15:05 UTC15m
2026-07-25 UAL878 HKG → SFO Jul 25, 14:51 UTCJul 26, 03:14 UTC12h 23m
2026-07-25 UAL869 SFO → HKG Jul 25, 11:20 UTCJul 25, 11:35 UTC15m
2026-07-24 UAL869 SFO → HKG Jul 24, 21:12 UTCJul 25, 10:26 UTC13h 14m
2026-07-24 UAL869 SFO → HKG Jul 24, 21:20 UTCJul 24, 21:55 UTC35m
2026-07-24 UAL838 NRT → SFO Jul 24, 08:30 UTCJul 24, 17:45 UTC9h 15m
2026-07-24 UAL838 NRT → SFO Jul 24, 08:31 UTCJul 24, 17:51 UTC9h 20m
2026-07-23 UAL79 EWR → NRT Jul 23, 16:02 UTCJul 24, 05:34 UTC13h 32m
2026-07-23 UAL79 EWR → NRT Jul 23, 16:05 UTCJul 24, 05:40 UTC13h 35m
2026-07-23 UAL2416 LAS → SFO Jul 23, 07:35 UTCJul 23, 12:00 UTC4h 25m
2026-07-22 UAL810 PHL → DEN Jul 22, 13:50 UTCJul 23, 02:35 UTC12h 45m
2026-07-21 UAL809 SEA → IAD Jul 21, 22:03 UTCJul 22, 11:01 UTC12h 58m
2026-07-21 UAL809 SEA → IAD Jul 21, 22:15 UTCJul 22, 10:25 UTC12h 10m
2026-07-21 UAL872 TPE → SFO Jul 21, 04:00 UTCJul 21, 14:00 UTC10h 0m
2026-07-21 UAL872 TPE → SFO Jul 21, 02:30 UTCJul 21, 02:40 UTC10m
2026-07-20 UAL871 - Jul 20, 09:50 UTCJul 20, 10:15 UTC25m
2026-07-19 UAL871 - Jul 19, 22:10 UTCJul 20, 08:35 UTC10h 25m
2026-07-19 UAL1960 MCO → ORD Jul 19, 11:50 UTCJul 19, 16:50 UTC5h 0m
2026-07-18 UAL78 - Jul 18, 15:50 UTCJul 18, 20:55 UTC5h 5m
2026-07-18 UAL78 - Jul 18, 08:45 UTCJul 18, 15:45 UTC7h 0m
2026-07-18 UAL78 NRT → EWR Jul 18, 08:51 UTCJul 18, 20:47 UTC11h 56m
2026-07-17 UAL79 EWR → NRT Jul 17, 15:55 UTCJul 18, 04:55 UTC13h 1m
2026-07-17 UAL2416 - Jul 17, 07:25 UTCJul 17, 12:04 UTC4h 40m
2026-07-16 UAL1844 - Jul 16, 22:40 UTCJul 17, 03:55 UTC5h 15m
2026-07-16 UAL41 - Jul 16, 09:35 UTCJul 16, 18:15 UTC8h 40m
2026-07-15 UAL40 - Jul 15, 23:20 UTCJul 16, 00:10 UTC50m
2026-07-15 UAL40 EWR → FCO Jul 15, 22:53 UTCJul 16, 07:00 UTC8h 7m
2026-07-15 UAL43 - Jul 15, 10:10 UTCJul 15, 17:40 UTC7h 30m
2026-07-15 UAL43 FRA → EWR Jul 15, 10:14 UTCJul 15, 17:39 UTC7h 25m
2026-07-14 UAL989 IAD → FRA Jul 14, 22:15 UTCJul 15, 05:40 UTC7h 24m
2026-07-14 UAL951 BRU → IAD Jul 14, 10:35 UTCJul 14, 17:50 UTC7h 15m
2026-07-13 UAL950 - Jul 13, 22:30 UTCJul 14, 00:25 UTC1h 55m
2026-07-13 UAL950 IAD → BRU Jul 13, 22:03 UTCJul 14, 05:26 UTC7h 23m
2026-07-13 UAL988 - Jul 13, 11:10 UTCJul 13, 19:00 UTC7h 50m
2026-07-13 UAL42 EWR → FRA Jul 13, 01:30 UTCJul 13, 08:30 UTC7h 0m
2026-07-12 UAL435 - Jul 12, 15:50 UTCJul 12, 20:40 UTC4h 50m
2026-07-11 UAL1844 - Jul 11, 23:25 UTCJul 12, 04:30 UTC5h 5m
2026-07-11 UAL1844 EWR → SFO Jul 11, 22:34 UTCJul 12, 04:24 UTC5h 50m
2026-07-11 UAL41 - Jul 11, 09:40 UTCJul 11, 11:40 UTC2h 0m
2026-07-11 UAL41 FCO → EWR Jul 11, 09:27 UTCJul 11, 18:08 UTC8h 41m
2026-07-10 UAL40 EWR → FCO Jul 10, 22:08 UTCJul 11, 05:54 UTC7h 46m
2026-07-10 UAL40 - Jul 10, 22:20 UTCJul 10, 23:50 UTC1h 30m
2026-07-10 UAL43 - Jul 10, 10:05 UTCJul 10, 18:15 UTC8h 10m
2026-07-10 UAL42 - Jul 10, 00:30 UTCJul 10, 01:55 UTC1h 25m
2026-07-10 UAL42 EWR → FRA Jul 10, 00:15 UTCJul 10, 07:28 UTC7h 13m
2026-07-09 UAL435 - Jul 9, 16:35 UTCJul 9, 21:30 UTC4h 55m
2026-07-09 UAL1346 - Jul 9, 08:55 UTCJul 9, 09:10 UTC15m

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 N2250U page for operator, model, and routing details .

Mode-S A1F5FF frequently asked

What is Mode-S code A1F5FF?
A1F5FF is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N2250U.
Where is Mode-S A1F5FF registered?
Mode-S code A1F5FF 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 A1F5FF broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 19:10 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A1F5FF, octal 50372777, decimal 10,614,271.
What flights does A1F5FF operate?
Mode-S A1F5FF has broadcast 20 distinct callsigns, including UAL1175, UAL950, UAL951, UAL201, UAL190.