Apparatus

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sensors Mode-S transponder

A1C82A

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N2138U · BOEING 777-300ER · operated by UNITED AIRLINES INC

Hex
A1C82A
Octal
50344052
Decimal
10,602,538
Country
US
Tail
N2138U
Type
B77W
No current signal · last broadcast 13h ago
Flights observed
212
Distinct callsigns
20
Country
US
Last broadcast
13h ago

Last known position

Most recent position reported by Mode-S A1C82A.

Country allocation

The ICAO 24-bit address A1C82A 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
UAL857 - 14 2026-06-22
UAL41 - 13 2026-07-13
UAL862 United Airlines 12 2026-06-07
UAL40 - 11 2026-07-12
UAL190 - 11 2026-07-05
UAL858 - 10 2026-06-24
UAL878 - 9 2026-07-03
UAL877 United Airlines 9 2026-06-06
UAL869 - 9 2026-07-03
UAL42 - 9 2026-07-08
UAL950 - 7 2026-07-08
UAL43 - 7 2026-07-11
UAL189 - 7 2026-07-04
UAL1149 United Airlines 7 2026-05-14
UAL989 - 6 2026-07-11
UAL988 - 6 2026-07-10
UAL838 United Airlines 6 2026-06-08
UAL1175 - 6 2026-07-05
UAL951 - 5 2026-07-09
UAL837 United Airlines 5 2026-06-30

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-13 UAL41 - Jul 13, 09:30 UTCJul 13, 10:30 UTC1h 0m
2026-07-13 UAL41 FCO → EWR Jul 13, 09:27 UTCJul 13, 18:11 UTC8h 44m
2026-07-13 UAL41 FCO → EWR Jul 13, 09:27 UTCJul 13, 18:13 UTC8h 46m
2026-07-12 UAL40 EWR → FCO Jul 12, 22:18 UTCJul 13, 05:58 UTC7h 40m
2026-07-12 UAL40 - Jul 12, 22:15 UTCJul 13, 06:01 UTC7h 45m
2026-07-12 UAL41 - Jul 12, 09:45 UTCJul 12, 18:15 UTC8h 30m
2026-07-11 UAL40 EWR → FCO Jul 11, 21:48 UTCJul 12, 05:33 UTC7h 45m
2026-07-11 UAL40 - Jul 11, 21:55 UTCJul 11, 22:30 UTC35m
2026-07-11 UAL43 FRA → EWR Jul 11, 10:51 UTCJul 11, 18:36 UTC7h 45m
2026-07-11 UAL43 FRA → EWR Jul 11, 10:45 UTCJul 11, 18:30 UTC7h 45m
2026-07-11 UAL989 IAD → FRA Jul 11, 01:15 UTCJul 11, 08:20 UTC7h 5m
2026-07-10 UAL988 - Jul 10, 12:50 UTCJul 10, 21:15 UTC8h 25m
2026-07-10 UAL989 IAD → FRA Jul 10, 02:50 UTCJul 10, 10:00 UTC7h 10m
2026-07-09 UAL951 BRU → IAD Jul 9, 10:25 UTCJul 9, 18:25 UTC8h 0m
2026-07-08 UAL950 IAD → BRU Jul 8, 22:28 UTCJul 9, 05:26 UTC6h 58m
2026-07-08 UAL950 - Jul 8, 22:30 UTCJul 9, 04:30 UTC6h 0m
2026-07-08 UAL988 - Jul 8, 10:45 UTCJul 8, 12:30 UTC1h 45m
2026-07-08 UAL988 FRA → IAD Jul 8, 10:39 UTCJul 8, 18:35 UTC7h 56m
2026-07-08 UAL42 EWR → FRA Jul 8, 00:20 UTCJul 8, 07:14 UTC6h 54m
2026-07-08 UAL42 - Jul 8, 00:10 UTCJul 8, 01:45 UTC1h 35m
2026-07-07 UAL435 SFO → EWR Jul 7, 15:35 UTCJul 7, 20:20 UTC4h 45m
2026-07-07 UAL1346 - Jul 7, 08:30 UTCJul 7, 12:55 UTC4h 25m
2026-07-05 UAL1175 - Jul 5, 21:15 UTCJul 5, 21:30 UTC15m
2026-07-05 UAL1175 - Jul 5, 16:40 UTCJul 5, 17:05 UTC25m
2026-07-05 UAL190 - Jul 5, 01:05 UTCJul 5, 13:10 UTC12h 5m
2026-07-05 UAL190 MNL → SFO Jul 5, 01:01 UTCJul 5, 13:06 UTC12h 5m
2026-07-04 UAL189 SFO → MNL Jul 4, 08:19 UTCJul 4, 21:06 UTC12h 47m
2026-07-04 UAL189 - Jul 4, 08:15 UTCJul 4, 20:30 UTC12h 15m
2026-07-03 UAL878 HKG → SFO Jul 3, 14:51 UTCJul 4, 03:21 UTC12h 30m
2026-07-03 UAL878 - Jul 3, 15:05 UTCJul 4, 03:25 UTC12h 20m
2026-07-03 UAL869 - Jul 3, 10:30 UTCJul 3, 10:40 UTC10m
2026-07-02 UAL869 - Jul 2, 21:35 UTCJul 3, 09:55 UTC12h 20m
2026-07-02 UAL1960 EWR → SFO Jul 2, 11:20 UTCJul 2, 16:16 UTC4h 56m
2026-07-02 UAL1960 EWR → SFO Jul 2, 11:10 UTCJul 2, 16:25 UTC5h 15m
2026-07-01 UAL78 NRT → EWR Jul 1, 08:45 UTCJul 1, 20:45 UTC12h 0m
2026-06-30 UAL837 SFO → NRT Jun 30, 20:10 UTCJul 1, 06:05 UTC9h 55m
2026-06-30 UAL190 - Jun 30, 01:14 UTCJun 30, 13:15 UTC12h 0m
2026-06-30 UAL190 MNL → SFO Jun 30, 01:01 UTCJun 30, 13:11 UTC12h 10m
2026-06-29 UAL189 SFO → MNL Jun 29, 08:35 UTCJun 29, 21:50 UTC13h 15m
2026-06-28 UAL878 HKG → SFO Jun 28, 14:51 UTCJun 29, 03:20 UTC12h 29m
2026-06-28 UAL878 - Jun 28, 14:45 UTCJun 29, 03:29 UTC12h 45m
2026-06-27 UAL869 SFO → HKG Jun 27, 21:12 UTCJun 28, 11:02 UTC13h 50m
2026-06-27 UAL869 - Jun 27, 21:15 UTCJun 27, 21:40 UTC25m
2026-06-25 UAL59 - Jun 25, 11:25 UTCJun 25, 21:59 UTC10h 35m
2026-06-25 UAL59 FRA → SFO Jun 25, 11:24 UTCJun 25, 21:56 UTC10h 32m
2026-06-24 UAL58 SFO → FRA Jun 24, 21:22 UTCJun 25, 07:22 UTC10h 0m
2026-06-24 UAL58 - Jun 24, 21:19 UTCJun 25, 07:30 UTC10h 10m
2026-06-24 UAL858 - Jun 24, 09:19 UTCJun 24, 17:40 UTC8h 20m
2026-06-24 UAL858 NRT → SFO Jun 24, 09:19 UTCJun 24, 17:38 UTC8h 19m
2026-06-24 UAL858 - Jun 24, 05:20 UTCJun 24, 07:40 UTC2h 20m

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 N2138U page for operator, model, and routing details .

Mode-S A1C82A frequently asked

What is Mode-S code A1C82A?
A1C82A is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N2138U.
Where is Mode-S A1C82A registered?
Mode-S code A1C82A 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 A1C82A broadcasting right now?
No active broadcast right now. Last signal was 13h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A1C82A, octal 50344052, decimal 10,602,538.
What flights does A1C82A operate?
Mode-S A1C82A has broadcast 20 distinct callsigns, including UAL857, UAL41, UAL862, UAL40, UAL190.