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 Jul 26, 22:45 UTC
Flights observed
486
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 22:45 UTC

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
UAL1763 United Airlines 6 2026-07-20
UAL1613 - 6 2026-07-12
UAL790 - 5 2026-07-12
UAL718 United Airlines 5 2026-04-29
UAL2192 - 5 2026-07-11
UAL1438 - 5 2026-06-21
UAL792 United Airlines 4 2026-06-02
UAL455 United Airlines 4 2026-07-26
UAL335 - 4 2026-07-03
UAL318 United Airlines 4 2026-05-06
UAL248 United Airlines 4 2026-06-08
UAL2386 - 4 2026-07-03
UAL2164 - 4 2026-07-15
UAL1944 United Airlines 4 2026-07-23
UAL1942 - 4 2026-07-12
UAL1366 - 4 2026-07-16

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL2738 IAD → EWR Jul 26, 21:45 UTCJul 26, 22:45 UTC1h 0m
2026-07-26 UAL2765 HND → SFO Jul 26, 18:35 UTCJul 26, 19:45 UTC1h 10m
2026-07-26 UAL455 ORD → MSN Jul 26, 15:15 UTCJul 26, 16:25 UTC1h 10m
2026-07-26 UAL455 ORD → MSN Jul 26, 15:10 UTCJul 26, 16:12 UTC1h 2m
2026-07-26 UAL1285 BDL → IAH Jul 26, 12:40 UTCJul 26, 13:40 UTC1h 0m
2026-07-25 UAL2101 PBI → EWR Jul 25, 21:45 UTCJul 26, 01:05 UTC3h 20m
2026-07-25 UAL2205 CMH → IAH Jul 25, 15:20 UTCJul 25, 19:25 UTC4h 5m
2026-07-25 UAL1345 MIA → EWR Jul 25, 11:20 UTCJul 25, 14:00 UTC2h 40m
2026-07-25 UAL313 BOI → SFO Jul 25, 00:05 UTCJul 25, 02:50 UTC2h 45m
2026-07-24 UAL2682 EWR → RDU Jul 24, 21:20 UTCJul 24, 22:10 UTC50m
2026-07-24 UAL1564 BOS → ORD Jul 24, 17:25 UTCJul 24, 20:00 UTC2h 35m
2026-07-24 UAL1535 EWR → ORD Jul 24, 14:45 UTCJul 24, 15:20 UTC35m
2026-07-24 UAL529 IAH → EWR Jul 24, 12:40 UTCJul 24, 13:25 UTC45m
2026-07-24 UAL1524 IAH → EWR Jul 24, 10:25 UTCJul 24, 11:00 UTC35m
2026-07-24 UAL2677 CLE → DEN Jul 24, 03:20 UTCJul 24, 04:00 UTC40m
2026-07-24 UAL1460 SFO → DEN Jul 24, 00:00 UTCJul 24, 01:15 UTC1h 15m
2026-07-23 UAL1460 SFO → DEN Jul 23, 23:54 UTCJul 24, 01:16 UTC1h 22m
2026-07-23 UAL1109 RDU → EWR Jul 23, 20:05 UTCJul 23, 22:05 UTC2h 0m
2026-07-23 UAL1944 ORD → PHX Jul 23, 15:02 UTCJul 23, 18:03 UTC3h 1m
2026-07-23 UAL1944 ORD → PHX Jul 23, 15:00 UTCJul 23, 18:10 UTC3h 10m
2026-07-22 UAL1094 DEN → YYZ Jul 22, 23:45 UTCJul 23, 02:30 UTC2h 45m
2026-07-22 UAL1023 DEN → TPA Jul 22, 17:55 UTCJul 22, 19:55 UTC2h 0m
2026-07-22 UAL2149 DEN → SMF Jul 22, 14:10 UTCJul 22, 16:05 UTC1h 55m
2026-07-22 UAL355 BUR → SFO Jul 22, 11:15 UTCJul 22, 12:35 UTC1h 20m
2026-07-22 UAL1515 SNA → EWR Jul 22, 00:20 UTCJul 22, 03:25 UTC3h 5m
2026-07-21 UAL2262 LAS → SFO Jul 21, 21:45 UTCJul 21, 23:00 UTC1h 15m
2026-07-21 UAL2082 MDT → ORD Jul 21, 17:30 UTCJul 21, 19:25 UTC1h 55m
2026-07-21 UAL2383 PHL → DEN Jul 21, 12:40 UTCJul 21, 15:50 UTC3h 10m
2026-07-21 UAL2671 IAD → SAT Jul 21, 00:30 UTCJul 21, 03:25 UTC2h 55m
2026-07-20 UAL1790 EWR → MYR Jul 20, 20:10 UTCJul 20, 22:20 UTC2h 10m
2026-07-20 UAL8187 LGA → YUL Jul 20, 17:45 UTCJul 20, 18:35 UTC50m
2026-07-20 UAL8187 LGA → YUL Jul 20, 17:55 UTCJul 20, 18:28 UTC33m
2026-07-20 UAL2051 SFO → YVR Jul 20, 12:55 UTCJul 20, 15:50 UTC2h 55m
2026-07-20 UAL1763 SFO → AUS Jul 20, 02:55 UTCJul 20, 05:45 UTC2h 50m
2026-07-19 UAL3925 DEN → SFO Jul 19, 23:50 UTCJul 20, 01:55 UTC2h 5m
2026-07-19 UAL2027 DEN → DEN Jul 19, 18:50 UTCJul 19, 22:45 UTC3h 55m
2026-07-19 UAL1758 DEN → KOA Jul 19, 15:40 UTCJul 19, 17:40 UTC2h 0m
2026-07-19 UAL2718 - Jul 19, 14:00 UTCJul 19, 14:35 UTC35m
2026-07-19 UAL1334 - Jul 19, 04:35 UTCJul 19, 05:15 UTC40m
2026-07-18 UAL1702 BDL → IAH Jul 18, 19:35 UTCJul 19, 00:55 UTC5h 20m
2026-07-18 UAL2831 SEA → SFO Jul 18, 16:30 UTCJul 18, 18:20 UTC1h 50m
2026-07-18 UAL8120 YHZ → BOS Jul 18, 01:45 UTCJul 18, 03:15 UTC1h 31m
2026-07-18 UAL8120 YHZ → BOS Jul 18, 01:52 UTCJul 18, 03:11 UTC1h 19m
2026-07-17 UAL442 AUS → SFO Jul 17, 20:44 UTCJul 18, 00:04 UTC3h 20m
2026-07-17 UAL1061 - Jul 17, 17:09 UTCJul 17, 19:20 UTC2h 10m
2026-07-17 UAL466 CMH → ORD Jul 17, 13:15 UTCJul 17, 14:04 UTC50m
2026-07-17 UAL466 CMH → ORD Jul 17, 13:13 UTCJul 17, 13:51 UTC38m
2026-07-17 UAL1492 ORD → CMH Jul 17, 03:14 UTCJul 17, 04:04 UTC50m
2026-07-17 UAL1084 - Jul 17, 01:00 UTCJul 17, 01:05 UTC5m
2026-07-16 UAL1084 - Jul 16, 23:49 UTCJul 17, 01:05 UTC1h 15m

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 Jul 26, 22:45 UTC.
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, UAL1763.