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
- 227
- Distinct callsigns
- 20
- Country
- US
- Last broadcast
- Jul 26, 19:00 UTC
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 |
| UAL810 | United Airlines | 12 | 2026-07-18 |
| UAL857 | - | 11 | 2026-07-05 |
| UAL862 | - | 10 | 2026-07-17 |
| UAL809 | United Airlines | 10 | 2026-07-17 |
| UAL877 | - | 9 | 2026-07-16 |
| UAL1175 | United Airlines | 9 | 2026-07-23 |
| UAL858 | - | 8 | 2026-07-06 |
| UAL79 | - | 8 | 2026-07-11 |
| UAL869 | United Airlines | 7 | 2026-05-24 |
| UAL42 | United Airlines | 7 | 2026-07-26 |
| UAL200 | United Airlines | 7 | 2026-07-25 |
| UAL201 | United Airlines | 6 | 2026-07-24 |
| UAL190 | United Airlines | 6 | 2026-07-20 |
| 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 |
| UAL2416 | - | 5 | 2026-07-11 |
Recent flights last 50
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-07-26 | UAL988 | FRA → IAD | Jul 26, 10:50 UTC | Jul 26, 18:50 UTC | 8h 0m |
| 2026-07-26 | UAL42 | OGG → EWR | Jul 26, 00:00 UTC | Jul 26, 06:33 UTC | 6h 33m |
| 2026-07-25 | UAL42 | OGG → EWR | Jul 25, 23:55 UTC | Jul 26, 05:45 UTC | 5h 50m |
| 2026-07-25 | UAL435 | KOA → SFO | Jul 25, 15:55 UTC | Jul 25, 20:40 UTC | 4h 45m |
| 2026-07-25 | UAL1346 | DFW → EWR | Jul 25, 08:25 UTC | Jul 25, 08:35 UTC | 10m |
| 2026-07-25 | UAL1346 | DFW → EWR | Jul 25, 08:29 UTC | Jul 25, 12:34 UTC | 4h 5m |
| 2026-07-25 | UAL200 | GUM → HNL | Jul 25, 03:45 UTC | Jul 25, 04:10 UTC | 25m |
| 2026-07-24 | UAL201 | HNL → GUM | Jul 24, 01:15 UTC | Jul 24, 01:25 UTC | 10m |
| 2026-07-24 | UAL201 | HNL → GUM | Jul 24, 01:04 UTC | Jul 24, 08:09 UTC | 7h 5m |
| 2026-07-23 | UAL1175 | SFO → HNL | Jul 23, 21:30 UTC | Jul 23, 21:40 UTC | 10m |
| 2026-07-23 | UAL1175 | SFO → HNL | Jul 23, 16:45 UTC | Jul 23, 17:10 UTC | 25m |
| 2026-07-23 | UAL872 | TPE → SFO | Jul 23, 03:55 UTC | Jul 23, 13:45 UTC | 9h 50m |
| 2026-07-23 | UAL872 | TPE → SFO | Jul 23, 02:15 UTC | Jul 23, 02:30 UTC | 15m |
| 2026-07-21 | UAL871 | SFO → TPE | Jul 21, 22:08 UTC | Jul 22, 10:19 UTC | 12h 11m |
| 2026-07-21 | UAL871 | - | Jul 21, 22:25 UTC | Jul 21, 22:50 UTC | 25m |
| 2026-07-20 | UAL190 | IAH → MIA | Jul 20, 01:15 UTC | Jul 20, 13:30 UTC | 12h 15m |
| 2026-07-19 | UAL189 | SFO → MNL | Jul 19, 08:40 UTC | Jul 19, 21:50 UTC | 13h 10m |
| 2026-07-18 | UAL810 | PHL → DEN | Jul 18, 14:00 UTC | Jul 19, 02:35 UTC | 12h 35m |
| 2026-07-17 | UAL809 | SEA → IAD | Jul 17, 22:05 UTC | Jul 17, 22:40 UTC | 35m |
| 2026-07-17 | UAL809 | SEA → IAD | Jul 17, 21:54 UTC | Jul 18, 10:52 UTC | 12h 58m |
| 2026-07-17 | UAL862 | HKG → SFO | Jul 17, 04:26 UTC | Jul 17, 17:08 UTC | 12h 42m |
| 2026-07-17 | UAL862 | - | Jul 17, 04:20 UTC | Jul 17, 08:25 UTC | 4h 5m |
| 2026-07-16 | UAL877 | - | Jul 16, 07:45 UTC | Jul 16, 20:49 UTC | 13h 5m |
| 2026-07-15 | UAL810 | - | Jul 15, 13:35 UTC | Jul 16, 02:05 UTC | 12h 30m |
| 2026-07-14 | UAL809 | SFO → MNL | Jul 14, 21:43 UTC | Jul 15, 10:32 UTC | 12h 49m |
| 2026-07-14 | UAL809 | SFO → MNL | Jul 14, 21:45 UTC | Jul 15, 10:40 UTC | 12h 54m |
| 2026-07-14 | UAL872 | TPE → SFO | Jul 14, 02:23 UTC | Jul 14, 13:53 UTC | 11h 30m |
| 2026-07-14 | UAL872 | - | Jul 14, 02:20 UTC | Jul 14, 13:45 UTC | 11h 25m |
| 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 |
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 .