Apparatus

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sensors Mode-S transponder

A55EF3

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N445UA · AIRBUS A-320 · operated by UNITED AIRLINES INC

Hex
A55EF3
Octal
51257363
Decimal
10,837,747
Country
US
Tail
N445UA
Type
A320
No current signal · last broadcast 5h ago
Flights observed
424
Distinct callsigns
20
Country
US
Last broadcast
5h ago

Last known position

Most recent position reported by Mode-S A55EF3.

Country allocation

The ICAO 24-bit address A55EF3 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
UAL817 - 7 2026-07-05
UAL737 - 6 2026-07-11
UAL626 - 6 2026-06-29
UAL304 - 6 2026-07-10
UAL1613 - 6 2026-07-12
UAL790 - 5 2026-07-12
UAL718 United Airlines 5 2026-04-29
UAL2192 - 5 2026-07-11
UAL1763 - 5 2026-06-30
UAL1438 - 5 2026-06-21
UAL792 United Airlines 4 2026-06-02
UAL335 - 4 2026-07-03
UAL318 United Airlines 4 2026-05-06
UAL248 United Airlines 4 2026-06-08
UAL2386 - 4 2026-07-03
UAL1942 - 4 2026-07-12
UAL1216 - 4 2026-07-11
UAL477 United Airlines 3 2026-05-08
UAL2850 - 3 2026-07-03
UAL2773 - 3 2026-06-23

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-14 UAL1126 DEN → FAR Jul 14, 00:40 UTCJul 14, 02:05 UTC1h 25m
2026-07-13 UAL1762 - Jul 13, 19:55 UTCJul 13, 23:05 UTC3h 10m
2026-07-13 UAL2427 - Jul 13, 16:05 UTCJul 13, 18:30 UTC2h 25m
2026-07-13 UAL1338 DTW → ORD Jul 13, 13:00 UTCJul 13, 13:55 UTC55m
2026-07-13 UAL1220 DEN → DTW Jul 13, 00:15 UTCJul 13, 02:40 UTC2h 25m
2026-07-12 UAL1942 EUG → DEN Jul 12, 20:25 UTCJul 12, 22:30 UTC2h 5m
2026-07-12 UAL790 - Jul 12, 17:45 UTCJul 12, 18:45 UTC1h 0m
2026-07-12 UAL2317 - Jul 12, 15:50 UTCJul 12, 16:35 UTC45m
2026-07-12 UAL1613 - Jul 12, 00:35 UTCJul 12, 01:05 UTC30m
2026-07-11 UAL737 SEA → SFO Jul 11, 20:55 UTCJul 11, 22:55 UTC2h 0m
2026-07-11 UAL2192 SFO → SEA Jul 11, 17:55 UTCJul 11, 19:20 UTC1h 25m
2026-07-11 UAL2051 - Jul 11, 12:55 UTCJul 11, 16:20 UTC3h 25m
2026-07-11 UAL1216 - Jul 11, 01:40 UTCJul 11, 03:20 UTC1h 40m
2026-07-10 UAL1166 - Jul 10, 21:50 UTCJul 10, 23:10 UTC1h 20m
2026-07-10 UAL304 - Jul 10, 18:00 UTCJul 10, 19:25 UTC1h 25m
2026-07-10 UAL304 IAH → PVR Jul 10, 17:38 UTCJul 10, 20:05 UTC2h 27m
2026-07-10 UAL2662 - Jul 10, 13:10 UTCJul 10, 15:00 UTC1h 50m
2026-07-10 UAL8236 DEN → OMA Jul 10, 02:10 UTCJul 10, 03:15 UTC1h 5m
2026-07-09 UAL1942 EUG → DEN Jul 9, 21:55 UTCJul 10, 00:00 UTC2h 5m
2026-07-09 UAL790 - Jul 9, 19:10 UTCJul 9, 20:15 UTC1h 5m
2026-07-09 UAL790 SFO → EUG Jul 9, 19:14 UTCJul 9, 20:12 UTC58m
2026-07-09 UAL336 - Jul 9, 15:35 UTCJul 9, 17:10 UTC1h 35m
2026-07-09 UAL1958 - Jul 9, 01:25 UTCJul 9, 02:40 UTC1h 15m
2026-07-08 UAL454 DFW → SFO Jul 8, 20:35 UTCJul 8, 23:50 UTC3h 15m
2026-07-08 UAL1062 - Jul 8, 16:00 UTCJul 8, 18:55 UTC2h 55m
2026-07-08 UAL538 - Jul 8, 12:15 UTCJul 8, 14:20 UTC2h 5m
2026-07-08 UAL737 - Jul 8, 02:05 UTCJul 8, 04:00 UTC1h 55m
2026-07-07 UAL737 SEA → SFO Jul 7, 21:50 UTCJul 7, 23:35 UTC1h 45m
2026-07-07 UAL2192 - Jul 7, 18:30 UTCJul 7, 20:05 UTC1h 35m
2026-07-07 UAL1578 IAH → LAX Jul 7, 14:55 UTCJul 7, 16:45 UTC1h 50m
2026-07-07 UAL8107 - Jul 7, 04:15 UTCJul 7, 05:45 UTC1h 30m
2026-07-07 UAL8107 SFO → SEA Jul 7, 04:09 UTCJul 7, 05:36 UTC1h 27m
2026-07-07 UAL2164 - Jul 7, 00:45 UTCJul 7, 02:45 UTC2h 0m
2026-07-06 UAL1265 OAK → SEA Jul 6, 21:30 UTCJul 6, 23:00 UTC1h 30m
2026-07-06 UAL822 MEX → SFO Jul 6, 11:30 UTCJul 6, 15:30 UTC4h 0m
2026-07-05 UAL817 - Jul 5, 22:30 UTCJul 6, 00:30 UTC2h 0m
2026-07-05 UAL817 SFO → MEX Jul 5, 22:29 UTCJul 6, 02:31 UTC4h 2m
2026-07-05 UAL2029 SEA → SFO Jul 5, 12:30 UTCJul 5, 14:20 UTC1h 50m
2026-07-05 UAL1389 SFO → SEA Jul 5, 08:05 UTCJul 5, 09:30 UTC1h 25m
2026-07-05 UAL8245 - Jul 5, 04:00 UTCJul 5, 04:15 UTC15m
2026-07-05 UAL8245 SEA → SFO Jul 5, 02:10 UTCJul 5, 03:55 UTC1h 45m
2026-07-04 UAL325 - Jul 4, 19:00 UTCJul 4, 21:10 UTC2h 10m
2026-07-04 UAL1896 - Jul 4, 16:10 UTCJul 4, 17:05 UTC55m
2026-07-04 UAL790 DFW → SFO Jul 4, 11:15 UTCJul 4, 14:35 UTC3h 20m
2026-07-04 UAL1722 - Jul 4, 07:10 UTCJul 4, 10:00 UTC2h 50m
2026-07-04 UAL292 AUS → SFO Jul 4, 01:14 UTCJul 4, 04:40 UTC3h 26m
2026-07-04 UAL292 AUS → SFO Jul 4, 01:20 UTCJul 4, 04:45 UTC3h 25m
2026-07-03 UAL1116 HAF → AUS Jul 3, 20:25 UTCJul 3, 23:25 UTC3h 0m
2026-07-03 UAL2386 BUR → SFO Jul 3, 18:15 UTCJul 3, 19:10 UTC55m
2026-07-03 UAL2363 HAF → BUR Jul 3, 15:50 UTCJul 3, 16:40 UTC50m

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 N445UA page for operator, model, and routing details .

Mode-S A55EF3 frequently asked

What is Mode-S code A55EF3?
A55EF3 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N445UA.
Where is Mode-S A55EF3 registered?
Mode-S code A55EF3 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 A55EF3 broadcasting right now?
No active broadcast right now. Last signal was 5h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A55EF3, octal 51257363, decimal 10,837,747.
What flights does A55EF3 operate?
Mode-S A55EF3 has broadcast 20 distinct callsigns, including UAL817, UAL737, UAL626, UAL304, UAL1613.