sensors Mode-S transponder
A2CB12
ICAO 24-bit transponder address · allocated to United States
Currently assigned to N27957 · BOEING 787-9 Dreamliner · operated by UNITED AIRLINES INC
- Hex
- A2CB12
- Octal
- 50545422
- Decimal
- 10,668,818
- Country
- US
- Tail
- N27957
- Type
- B789
- Flights observed
- 216
- Distinct callsigns
- 20
- Country
- US
- Last broadcast
- 11h ago
Last known position
Country allocation
The ICAO 24-bit address A2CB12 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 |
|---|---|---|---|
| UAL83 | United Airlines | 11 | 2026-06-18 |
| UAL82 | - | 11 | 2026-06-18 |
| UAL820 | United Airlines | 7 | 2026-06-11 |
| UAL713 | United Airlines | 7 | 2026-06-02 |
| UAL821 | United Airlines | 6 | 2026-06-11 |
| UAL62 | United Airlines | 6 | 2026-05-07 |
| UAL29 | - | 6 | 2026-07-04 |
| UAL28 | - | 6 | 2026-07-01 |
| UAL1849 | United Airlines | 6 | 2026-05-31 |
| UAL1757 | United Airlines | 6 | 2026-05-31 |
| UAL935 | - | 5 | 2026-07-07 |
| UAL7 | United Airlines | 5 | 2026-05-08 |
| UAL6 | United Airlines | 5 | 2026-05-06 |
| UAL1960 | United Airlines | 5 | 2026-04-21 |
| UAL923 | - | 4 | 2026-06-13 |
| UAL893 | - | 4 | 2026-06-26 |
| UAL870 | - | 4 | 2026-06-22 |
| UAL863 | - | 4 | 2026-06-21 |
| UAL771 | United Airlines | 4 | 2026-06-12 |
| UAL60 | - | 4 | 2026-06-25 |
Recent flights last 50
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-07-13 | UAL2222 | - | Jul 13, 18:05 UTC | Jul 13, 18:20 UTC | 15m |
| 2026-07-13 | UAL1122 | - | Jul 13, 14:55 UTC | Jul 13, 15:05 UTC | 10m |
| 2026-07-13 | UAL1122 | - | Jul 13, 01:05 UTC | Jul 13, 01:40 UTC | 35m |
| 2026-07-12 | UAL8196 | - | Jul 12, 15:50 UTC | Jul 12, 20:35 UTC | 4h 45m |
| 2026-07-12 | UAL8196 | LAX → EWR | Jul 12, 15:41 UTC | Jul 12, 20:30 UTC | 4h 49m |
| 2026-07-11 | UAL199 | PVG → LAX | Jul 11, 12:16 UTC | Jul 11, 23:56 UTC | 11h 40m |
| 2026-07-11 | UAL199 | - | Jul 11, 07:05 UTC | Jul 12, 00:05 UTC | 17h 0m |
| 2026-07-10 | UAL198 | LAX → PVG | Jul 10, 20:31 UTC | Jul 11, 09:54 UTC | 13h 23m |
| 2026-07-10 | UAL198 | - | Jul 10, 20:50 UTC | Jul 11, 14:45 UTC | 17h 55m |
| 2026-07-10 | UAL153 | HKG → LAX | Jul 10, 05:08 UTC | Jul 10, 18:13 UTC | 13h 5m |
| 2026-07-10 | UAL153 | - | Jul 10, 05:15 UTC | Jul 10, 05:30 UTC | 15m |
| 2026-07-10 | UAL153 | - | Jul 10, 02:30 UTC | Jul 10, 02:35 UTC | 5m |
| 2026-07-09 | UAL152 | - | Jul 9, 13:00 UTC | Jul 9, 13:15 UTC | 15m |
| 2026-07-09 | UAL152 | HKG → SGN | Jul 9, 12:49 UTC | Jul 9, 15:09 UTC | 2h 20m |
| 2026-07-08 | UAL152 | - | Jul 8, 20:15 UTC | Jul 9, 10:20 UTC | 14h 5m |
| 2026-07-07 | UAL935 | - | Jul 7, 12:30 UTC | Jul 7, 23:20 UTC | 10h 50m |
| 2026-07-07 | UAL948 | - | Jul 7, 00:10 UTC | Jul 7, 09:55 UTC | 9h 45m |
| 2026-07-06 | UAL114 | PPT → SFO | Jul 6, 07:30 UTC | Jul 6, 14:39 UTC | 7h 9m |
| 2026-07-06 | UAL114 | - | Jul 6, 07:05 UTC | Jul 6, 14:45 UTC | 7h 40m |
| 2026-07-05 | UAL115 | SFO → PPT | Jul 5, 20:52 UTC | Jul 6, 04:30 UTC | 7h 38m |
| 2026-07-05 | UAL115 | SFO → PPT | Jul 5, 20:45 UTC | Jul 6, 04:30 UTC | 7h 45m |
| 2026-07-05 | UAL28D | SIN → SFO | Jul 5, 05:00 UTC | Jul 5, 17:55 UTC | 12h 55m |
| 2026-07-04 | UAL29 | - | Jul 4, 10:20 UTC | Jul 4, 10:30 UTC | 10m |
| 2026-07-03 | UAL29 | - | Jul 3, 19:10 UTC | Jul 4, 09:10 UTC | 14h 0m |
| 2026-07-03 | UAL29 | SFO → SIN | Jul 3, 18:35 UTC | Jul 4, 10:28 UTC | 15h 53m |
| 2026-07-03 | UAL114 | PPT → SFO | Jul 3, 07:10 UTC | Jul 3, 14:55 UTC | 7h 45m |
| 2026-07-02 | UAL115 | - | Jul 2, 21:10 UTC | Jul 3, 05:00 UTC | 7h 50m |
| 2026-07-01 | UAL28 | - | Jul 1, 15:25 UTC | Jul 2, 04:30 UTC | 13h 5m |
| 2026-07-01 | UAL28 | - | Jul 1, 14:05 UTC | Jul 1, 14:15 UTC | 10m |
| 2026-07-01 | UAL29 | - | Jul 1, 10:10 UTC | Jul 1, 10:25 UTC | 15m |
| 2026-06-30 | UAL29 | - | Jun 30, 18:50 UTC | Jul 1, 08:55 UTC | 14h 5m |
| 2026-06-30 | UAL806 | - | Jun 30, 02:45 UTC | Jun 30, 12:30 UTC | 9h 45m |
| 2026-06-29 | UAL805 | SFO → ICN | Jun 29, 07:36 UTC | Jun 29, 19:35 UTC | 11h 59m |
| 2026-06-29 | UAL805 | - | Jun 29, 07:55 UTC | Jun 29, 18:30 UTC | 10h 35m |
| 2026-06-28 | UAL969 | - | Jun 28, 13:25 UTC | Jun 28, 14:30 UTC | 1h 5m |
| 2026-06-28 | UAL969 | AMS → SFO | Jun 28, 13:21 UTC | Jun 28, 23:10 UTC | 9h 49m |
| 2026-06-28 | UAL969 | AMS → SFO | Jun 28, 13:21 UTC | Jun 28, 23:10 UTC | 9h 49m |
| 2026-06-27 | UAL968 | - | Jun 27, 22:20 UTC | Jun 28, 08:00 UTC | 9h 40m |
| 2026-06-27 | UAL892 | - | Jun 27, 08:35 UTC | Jun 27, 18:35 UTC | 10h 0m |
| 2026-06-26 | UAL893 | SFO → ICN | Jun 26, 18:20 UTC | Jun 27, 06:25 UTC | 12h 5m |
| 2026-06-26 | UAL893 | SFO → ICN | Jun 26, 18:39 UTC | Jun 27, 06:35 UTC | 11h 55m |
| 2026-06-26 | UAL61 | - | Jun 26, 01:45 UTC | Jun 26, 15:34 UTC | 13h 50m |
| 2026-06-25 | UAL60 | SFO → MEL | Jun 25, 07:04 UTC | Jun 25, 22:42 UTC | 15h 38m |
| 2026-06-25 | UAL60 | - | Jun 25, 07:25 UTC | Jun 25, 22:29 UTC | 15h 5m |
| 2026-06-24 | UAL892 | ICN → SFO | Jun 24, 08:16 UTC | Jun 24, 17:47 UTC | 9h 31m |
| 2026-06-24 | UAL892 | ICN → SFO | Jun 24, 08:04 UTC | Jun 24, 17:45 UTC | 9h 40m |
| 2026-06-23 | UAL893 | SFO → ICN | Jun 23, 18:10 UTC | Jun 24, 05:42 UTC | 11h 32m |
| 2026-06-23 | UAL893 | SFO → ICN | Jun 23, 18:20 UTC | Jun 24, 05:49 UTC | 11h 30m |
| 2026-06-22 | UAL870 | SYD → SFO | Jun 22, 00:55 UTC | Jun 22, 13:49 UTC | 12h 54m |
| 2026-06-22 | UAL870 | - | Jun 22, 00:50 UTC | Jun 22, 13:49 UTC | 13h 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 N27957 page for operator, model, and routing details .