Apparatus

Try JFK, AAL1290, BAW, or N225AN.

sensors Mode-S transponder

A1C7C1

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N2135U · BOEING 777-300ER · operated by UNITED AIRLINES INC

Hex
A1C7C1
Octal
50343701
Decimal
10,602,433
Country
US
Tail
N2135U
Type
B77W
No current signal · last broadcast Jul 26, 22:15 UTC
Flights observed
268
Distinct callsigns
20
Country
US
Last broadcast
Jul 26, 22:15 UTC

Last known position

Most recent position reported by Mode-S A1C7C1.

Country allocation

The ICAO 24-bit address A1C7C1 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
UAL41 United Airlines 18 2026-07-03
UAL40 - 18 2026-07-02
UAL869 United Airlines 14 2026-07-22
UAL862 United Airlines 14 2026-07-24
UAL43 - 14 2026-06-19
UAL872 - 12 2026-07-09
UAL1175 - 12 2026-07-11
UAL810 United Airlines 11 2026-07-25
UAL201 - 11 2026-07-12
UAL877 United Airlines 10 2026-07-23
UAL871 - 10 2026-07-08
UAL42 - 10 2026-06-17
UAL878 United Airlines 9 2026-07-22
UAL809 United Airlines 9 2026-07-26
UAL1960 United Airlines 8 2026-06-09
UAL1346 - 7 2026-07-13
UAL200 - 6 2026-07-13
UAL190 - 6 2026-06-26
UAL189 - 6 2026-06-25
UAL989 - 4 2026-06-18

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 UAL809 SEA → IAD Jul 26, 22:10 UTCJul 26, 22:15 UTC5m
2026-07-25 UAL810 PHL → DEN Jul 25, 18:05 UTCJul 26, 06:30 UTC12h 25m
2026-07-25 UAL809 SEA → IAD Jul 25, 02:48 UTCJul 25, 15:37 UTC12h 49m
2026-07-25 UAL809 SEA → IAD Jul 25, 02:40 UTCJul 25, 03:10 UTC30m
2026-07-24 UAL862 HKG → SFO Jul 24, 04:21 UTCJul 24, 16:39 UTC12h 18m
2026-07-24 UAL862 HKG → SFO Jul 24, 04:20 UTCJul 24, 13:00 UTC8h 40m
2026-07-23 UAL877 SFO → HKG Jul 23, 07:31 UTCJul 23, 20:39 UTC13h 8m
2026-07-23 UAL877 SFO → HKG Jul 23, 07:35 UTCJul 23, 20:35 UTC13h 0m
2026-07-22 UAL878 HKG → SFO Jul 22, 15:00 UTCJul 23, 03:35 UTC12h 35m
2026-07-22 UAL869 SFO → HKG Jul 22, 11:10 UTCJul 22, 11:30 UTC20m
2026-07-21 UAL869 SFO → HKG Jul 21, 21:19 UTCJul 22, 10:24 UTC13h 5m
2026-07-21 UAL869 SFO → HKG Jul 21, 21:25 UTCJul 21, 21:50 UTC25m
2026-07-21 UAL858 ICN → SFO Jul 21, 15:55 UTCJul 21, 16:00 UTC5m
2026-07-21 UAL858 ICN → SFO Jul 21, 05:35 UTCJul 21, 15:50 UTC10h 15m
2026-07-20 UAL857 ICN → PVG Jul 20, 06:20 UTCJul 21, 06:15 UTC23h 54m
2026-07-19 UAL857 ICN → PVG Jul 19, 21:00 UTCJul 20, 07:55 UTC10h 55m
2026-07-19 UAL862 HKG → SFO Jul 19, 04:11 UTCJul 19, 16:44 UTC12h 33m
2026-07-19 UAL862 HKG → SFO Jul 19, 04:15 UTCJul 19, 16:45 UTC12h 30m
2026-07-18 UAL877 - Jul 18, 07:45 UTCJul 18, 08:15 UTC30m
2026-07-18 UAL877 SFO → HKG Jul 18, 07:29 UTCJul 18, 20:35 UTC13h 6m
2026-07-17 UAL878 HKG → SFO Jul 17, 14:51 UTCJul 18, 03:23 UTC12h 32m
2026-07-17 UAL878 - Jul 17, 14:50 UTCJul 17, 18:34 UTC3h 45m
2026-07-16 UAL869 - Jul 16, 21:30 UTCJul 16, 22:10 UTC40m
2026-07-16 UAL869 SFO → HKG Jul 16, 21:12 UTCJul 17, 10:15 UTC13h 3m
2026-07-16 UAL862 HKG → SFO Jul 16, 04:55 UTCJul 16, 17:35 UTC12h 40m
2026-07-15 UAL877 SFO → HKG Jul 15, 07:25 UTCJul 15, 20:35 UTC13h 10m
2026-07-14 UAL810 - Jul 14, 13:45 UTCJul 15, 02:15 UTC12h 29m
2026-07-14 UAL810 MNL → SFO Jul 14, 13:41 UTCJul 15, 02:11 UTC12h 30m
2026-07-13 UAL809 SFO → MNL Jul 13, 22:08 UTCJul 14, 11:00 UTC12h 52m
2026-07-13 UAL809 - Jul 13, 22:10 UTCJul 13, 22:35 UTC25m
2026-07-13 UAL1346 - Jul 13, 12:15 UTCJul 13, 13:10 UTC55m
2026-07-13 UAL200 - Jul 13, 03:50 UTCJul 13, 04:05 UTC15m
2026-07-12 UAL201 - Jul 12, 00:55 UTCJul 12, 01:05 UTC10m
2026-07-12 UAL201 HNL → GUM Jul 12, 00:44 UTCJul 12, 07:57 UTC7h 13m
2026-07-11 UAL1175 - Jul 11, 16:45 UTCJul 11, 21:25 UTC4h 40m
2026-07-11 UAL1346 - Jul 11, 08:25 UTCJul 11, 12:45 UTC4h 20m
2026-07-10 UAL201 - Jul 10, 00:55 UTCJul 10, 01:10 UTC15m
2026-07-09 UAL1175 - Jul 9, 21:20 UTCJul 9, 21:35 UTC15m
2026-07-09 UAL1175 SFO → HNL Jul 9, 16:53 UTCJul 9, 21:30 UTC4h 37m
2026-07-09 UAL1175 - Jul 9, 16:50 UTCJul 9, 17:15 UTC25m
2026-07-09 UAL872 - Jul 9, 03:45 UTCJul 9, 13:30 UTC9h 45m
2026-07-09 UAL872 - Jul 9, 02:15 UTCJul 9, 02:25 UTC10m
2026-07-08 UAL871 - Jul 8, 10:20 UTCJul 8, 10:45 UTC25m
2026-07-07 UAL871 - Jul 7, 22:20 UTCJul 8, 09:10 UTC10h 50m
2026-07-07 UAL862 - Jul 7, 04:55 UTCJul 7, 06:55 UTC2h 0m
2026-07-07 UAL862 HKG → SFO Jul 7, 04:26 UTCJul 7, 17:17 UTC12h 51m
2026-07-06 UAL877 - Jul 6, 07:40 UTCJul 6, 21:00 UTC13h 20m
2026-07-05 UAL878 - Jul 5, 14:40 UTCJul 6, 02:55 UTC12h 15m
2026-07-04 UAL869 SFO → HKG Jul 4, 21:17 UTCJul 5, 10:49 UTC13h 32m
2026-07-04 UAL869 SFO → HKG Jul 4, 21:25 UTCJul 5, 10:50 UTC13h 25m

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 N2135U page for operator, model, and routing details .

Mode-S A1C7C1 frequently asked

What is Mode-S code A1C7C1?
A1C7C1 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N2135U.
Where is Mode-S A1C7C1 registered?
Mode-S code A1C7C1 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 A1C7C1 broadcasting right now?
No active broadcast right now. Last signal was Jul 26, 22:15 UTC.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A1C7C1, octal 50343701, decimal 10,602,433.
What flights does A1C7C1 operate?
Mode-S A1C7C1 has broadcast 20 distinct callsigns, including UAL41, UAL40, UAL869, UAL862, UAL43.