sensors Mode-S transponder
A1CB0F
ICAO 24-bit transponder address · allocated to United States
Currently assigned to N2142U · BOEING 777-300ER · operated by UNITED AIRLINES INC
- Hex
- A1CB0F
- Octal
- 50345417
- Decimal
- 10,603,279
- Country
- US
- Tail
- N2142U
- Type
- B77W
- Flights observed
- 201
- Distinct callsigns
- 20
- Country
- US
- Last broadcast
- 2h ago
Last known position
Country allocation
The ICAO 24-bit address A1CB0F 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 |
|---|---|---|---|
| UAL40 | United Airlines | 14 | 2026-06-05 |
| UAL41 | United Airlines | 13 | 2026-06-06 |
| UAL857 | - | 11 | 2026-07-05 |
| UAL810 | - | 10 | 2026-07-10 |
| UAL877 | - | 8 | 2026-07-03 |
| UAL862 | - | 8 | 2026-07-04 |
| UAL858 | - | 8 | 2026-07-06 |
| UAL79 | - | 8 | 2026-07-11 |
| UAL869 | United Airlines | 7 | 2026-05-24 |
| UAL1175 | United Airlines | 7 | 2026-05-26 |
| UAL809 | - | 6 | 2026-07-09 |
| UAL200 | United Airlines | 6 | 2026-05-28 |
| UAL951 | United Airlines | 5 | 2026-05-31 |
| UAL878 | United Airlines | 5 | 2026-05-24 |
| UAL78 | United Airlines | 5 | 2026-07-02 |
| UAL43 | United Airlines | 5 | 2026-06-05 |
| UAL42 | United Airlines | 5 | 2026-06-05 |
| UAL2416 | - | 5 | 2026-07-11 |
| UAL1960 | - | 5 | 2026-06-16 |
| UAL190 | United Airlines | 5 | 2026-05-26 |
Recent flights last 50
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-07-14 | UAL872 | - | Jul 14, 02:20 UTC | Jul 14, 02:40 UTC | 20m |
| 2026-07-14 | UAL872 | TPE → SFO | Jul 14, 02:23 UTC | Jul 14, 13:53 UTC | 11h 30m |
| 2026-07-12 | UAL871 | SFO → TPE | Jul 12, 22:15 UTC | Jul 13, 10:20 UTC | 12h 5m |
| 2026-07-12 | UAL838 | - | Jul 12, 08:30 UTC | Jul 12, 17:35 UTC | 9h 5m |
| 2026-07-12 | UAL838 | NRT → SFO | Jul 12, 08:31 UTC | Jul 12, 17:31 UTC | 9h 0m |
| 2026-07-11 | UAL79 | - | Jul 11, 16:35 UTC | Jul 11, 23:35 UTC | 7h 0m |
| 2026-07-11 | UAL79 | EWR → NRT | Jul 11, 16:04 UTC | Jul 12, 05:34 UTC | 13h 30m |
| 2026-07-11 | UAL2416 | SFO → EWR | Jul 11, 07:40 UTC | Jul 11, 12:15 UTC | 4h 35m |
| 2026-07-10 | UAL810 | MNL → SFO | Jul 10, 14:14 UTC | Jul 11, 03:43 UTC | 13h 29m |
| 2026-07-10 | UAL810 | - | Jul 10, 14:30 UTC | Jul 11, 03:40 UTC | 13h 10m |
| 2026-07-09 | UAL809 | - | Jul 9, 22:00 UTC | Jul 10, 11:35 UTC | 13h 35m |
| 2026-07-09 | UAL852 | - | Jul 9, 06:45 UTC | Jul 9, 07:00 UTC | 15m |
| 2026-07-09 | UAL852 | TPE → SFO | Jul 9, 06:51 UTC | Jul 9, 18:02 UTC | 11h 11m |
| 2026-07-08 | UAL853 | - | Jul 8, 20:30 UTC | Jul 8, 21:00 UTC | 30m |
| 2026-07-08 | UAL853 | SFO → TPE | Jul 8, 08:48 UTC | Jul 8, 20:37 UTC | 11h 49m |
| 2026-07-08 | UAL853 | - | Jul 8, 08:30 UTC | Jul 8, 19:15 UTC | 10h 45m |
| 2026-07-07 | UAL810 | - | Jul 7, 14:05 UTC | Jul 7, 14:35 UTC | 30m |
| 2026-07-07 | UAL810 | MNL → SFO | Jul 7, 13:41 UTC | Jul 8, 02:12 UTC | 12h 31m |
| 2026-07-06 | UAL809 | SFO → MNL | Jul 6, 21:58 UTC | Jul 7, 10:56 UTC | 12h 58m |
| 2026-07-06 | UAL809 | - | Jul 6, 21:55 UTC | Jul 6, 22:20 UTC | 25m |
| 2026-07-06 | UAL858 | - | Jul 6, 05:05 UTC | Jul 6, 06:30 UTC | 1h 25m |
| 2026-07-06 | UAL858 | PVG → SFO | Jul 6, 04:44 UTC | Jul 6, 14:54 UTC | 10h 10m |
| 2026-07-05 | UAL858 | - | Jul 5, 07:50 UTC | Jul 6, 06:30 UTC | 22h 40m |
| 2026-07-05 | UAL857 | - | Jul 5, 06:45 UTC | Jul 6, 05:45 UTC | 23h 0m |
| 2026-07-04 | UAL857 | - | Jul 4, 21:35 UTC | Jul 4, 22:05 UTC | 30m |
| 2026-07-04 | UAL857 | SFO → PVG | Jul 4, 20:57 UTC | Jul 5, 09:48 UTC | 12h 51m |
| 2026-07-04 | UAL862 | - | Jul 4, 04:45 UTC | Jul 4, 16:30 UTC | 11h 45m |
| 2026-07-04 | UAL862 | HKG → SFO | Jul 4, 04:11 UTC | Jul 4, 16:28 UTC | 12h 17m |
| 2026-07-04 | UAL862 | - | Jul 4, 03:55 UTC | Jul 4, 04:10 UTC | 15m |
| 2026-07-03 | UAL877 | SFO → HKG | Jul 3, 08:11 UTC | Jul 3, 21:08 UTC | 12h 57m |
| 2026-07-03 | UAL877 | SFO → HKG | Jul 3, 08:00 UTC | Jul 3, 21:15 UTC | 13h 15m |
| 2026-07-03 | UAL1844 | - | Jul 3, 00:05 UTC | Jul 3, 05:10 UTC | 5h 5m |
| 2026-07-02 | UAL78 | NRT → EWR | Jul 2, 08:50 UTC | Jul 2, 17:45 UTC | 8h 55m |
| 2026-07-02 | UAL78 | NRT → EWR | Jul 2, 08:51 UTC | Jul 2, 20:51 UTC | 12h 0m |
| 2026-07-01 | UAL79 | EWR → NRT | Jul 1, 16:09 UTC | Jul 2, 05:03 UTC | 12h 54m |
| 2026-07-01 | UAL79 | EWR → NRT | Jul 1, 16:10 UTC | Jul 2, 05:00 UTC | 12h 50m |
| 2026-07-01 | UAL2416 | - | Jul 1, 07:25 UTC | Jul 1, 12:05 UTC | 4h 40m |
| 2026-06-30 | UAL1844 | - | Jun 30, 00:35 UTC | Jun 30, 05:45 UTC | 5h 10m |
| 2026-06-28 | UAL2416 | - | Jun 28, 07:44 UTC | Jun 28, 12:09 UTC | 4h 25m |
| 2026-06-27 | UAL838D | - | Jun 27, 09:04 UTC | Jun 27, 17:55 UTC | 8h 50m |
| 2026-06-26 | UAL837 | SFO → NRT | Jun 26, 19:55 UTC | Jun 27, 06:15 UTC | 10h 20m |
| 2026-06-26 | UAL858 | - | Jun 26, 05:24 UTC | Jun 26, 14:50 UTC | 9h 25m |
| 2026-06-26 | UAL858 | PVG → SFO | Jun 26, 04:44 UTC | Jun 26, 14:47 UTC | 10h 3m |
| 2026-06-25 | UAL858 | - | Jun 25, 07:49 UTC | Jun 26, 06:45 UTC | 22h 55m |
| 2026-06-25 | UAL857 | - | Jun 25, 06:35 UTC | Jun 26, 05:44 UTC | 23h 10m |
| 2026-06-24 | UAL857 | - | Jun 24, 21:19 UTC | Jun 25, 08:24 UTC | 11h 5m |
| 2026-06-24 | UAL857 | SFO → PVG | Jun 24, 21:09 UTC | Jun 25, 09:20 UTC | 12h 11m |
| 2026-06-24 | UAL862 | - | Jun 24, 04:00 UTC | Jun 24, 16:19 UTC | 12h 20m |
| 2026-06-23 | UAL877 | - | Jun 23, 20:34 UTC | Jun 23, 20:49 UTC | 15m |
| 2026-06-23 | UAL877 | - | Jun 23, 07:25 UTC | Jun 23, 19:59 UTC | 12h 35m |
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 N2142U page for operator, model, and routing details .