sensors Mode-S transponder
A290D0
ICAO 24-bit transponder address · allocated to United States
Currently assigned to N2644U · BOEING 777-300ER · operated by UNITED AIRLINES INC
- Hex
- A290D0
- Octal
- 50510320
- Decimal
- 10,653,904
- Country
- US
- Tail
- N2644U
- Type
- B77W
- Flights observed
- 139
- Distinct callsigns
- 20
- Country
- US
- Last broadcast
- 1d ago
Last known position
Country allocation
The ICAO 24-bit address A290D0 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 |
|---|---|---|---|
| UAL810 | - | 12 | 2026-07-09 |
| UAL809 | - | 11 | 2026-07-08 |
| UAL862 | - | 8 | 2026-07-11 |
| UAL872 | - | 7 | 2026-06-29 |
| UAL871 | - | 7 | 2026-06-27 |
| UAL869 | - | 7 | 2026-07-06 |
| UAL78 | - | 7 | 2026-07-12 |
| UAL878 | - | 6 | 2026-07-06 |
| UAL190 | - | 6 | 2026-06-16 |
| UAL877 | - | 5 | 2026-07-10 |
| UAL857 | United Airlines | 5 | 2026-05-21 |
| UAL837 | - | 5 | 2026-07-11 |
| UAL1175 | - | 5 | 2026-06-29 |
| UAL189 | - | 4 | 2026-06-15 |
| UAL876 | United Airlines | 3 | 2026-05-14 |
| UAL858 | United Airlines | 3 | 2026-05-22 |
| UAL838 | - | 3 | 2026-07-08 |
| UAL435 | - | 3 | 2026-07-01 |
| UAL201 | - | 3 | 2026-06-30 |
| UAL200 | - | 3 | 2026-07-01 |
Recent flights last 50
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-07-13 | UAL1844 | - | Jul 13, 00:15 UTC | Jul 13, 05:05 UTC | 4h 50m |
| 2026-07-12 | UAL78 | NRT → EWR | Jul 12, 08:51 UTC | Jul 12, 20:36 UTC | 11h 45m |
| 2026-07-12 | UAL78 | - | Jul 12, 08:35 UTC | Jul 12, 09:05 UTC | 30m |
| 2026-07-11 | UAL837 | - | Jul 11, 20:00 UTC | Jul 12, 06:01 UTC | 10h 0m |
| 2026-07-11 | UAL862 | - | Jul 11, 06:40 UTC | Jul 11, 08:20 UTC | 1h 40m |
| 2026-07-11 | UAL862 | HKG → SFO | Jul 11, 04:11 UTC | Jul 11, 17:04 UTC | 12h 53m |
| 2026-07-11 | UAL862 | - | Jul 11, 04:20 UTC | Jul 11, 04:35 UTC | 15m |
| 2026-07-10 | UAL877 | SFO → HKG | Jul 10, 08:05 UTC | Jul 10, 21:25 UTC | 13h 20m |
| 2026-07-09 | UAL810 | MNL → SFO | Jul 9, 13:41 UTC | Jul 10, 02:05 UTC | 12h 24m |
| 2026-07-09 | UAL810 | - | Jul 9, 13:45 UTC | Jul 10, 02:15 UTC | 12h 30m |
| 2026-07-09 | UAL810 | MNL → SFO | Jul 9, 13:41 UTC | Jul 10, 02:15 UTC | 12h 34m |
| 2026-07-08 | UAL809 | SFO → MNL | Jul 8, 22:03 UTC | Jul 9, 11:15 UTC | 13h 12m |
| 2026-07-08 | UAL809 | SFO → MNL | Jul 8, 22:05 UTC | Jul 9, 11:20 UTC | 13h 15m |
| 2026-07-08 | UAL838 | - | Jul 8, 08:40 UTC | Jul 8, 17:40 UTC | 9h 0m |
| 2026-07-08 | UAL838 | NRT → SFO | Jul 8, 08:41 UTC | Jul 8, 17:33 UTC | 8h 52m |
| 2026-07-07 | UAL79 | EWR → NRT | Jul 7, 16:35 UTC | Jul 8, 06:15 UTC | 13h 40m |
| 2026-07-07 | UAL2416 | SFO → EWR | Jul 7, 07:30 UTC | Jul 7, 12:20 UTC | 4h 50m |
| 2026-07-06 | UAL878 | HKG → SFO | Jul 6, 14:51 UTC | Jul 7, 03:02 UTC | 12h 11m |
| 2026-07-06 | UAL878 | HKG → SFO | Jul 6, 14:51 UTC | Jul 7, 03:00 UTC | 12h 9m |
| 2026-07-06 | UAL878 | - | Jul 6, 14:50 UTC | Jul 6, 16:45 UTC | 1h 55m |
| 2026-07-06 | UAL869 | - | Jul 6, 10:20 UTC | Jul 6, 10:40 UTC | 20m |
| 2026-07-05 | UAL869 | - | Jul 5, 21:10 UTC | Jul 6, 09:50 UTC | 12h 40m |
| 2026-07-05 | UAL1960 | - | Jul 5, 12:10 UTC | Jul 5, 17:15 UTC | 5h 5m |
| 2026-07-04 | UAL78 | NRT → EWR | Jul 4, 08:50 UTC | Jul 4, 18:00 UTC | 9h 10m |
| 2026-07-04 | UAL78 | NRT → EWR | Jul 4, 08:51 UTC | Jul 4, 20:55 UTC | 12h 4m |
| 2026-07-03 | UAL837 | SFO → NRT | Jul 3, 19:52 UTC | Jul 4, 05:57 UTC | 10h 5m |
| 2026-07-03 | UAL837 | SFO → NRT | Jul 3, 20:05 UTC | Jul 3, 20:30 UTC | 25m |
| 2026-07-03 | UAL1960 | - | Jul 3, 11:20 UTC | Jul 3, 16:40 UTC | 5h 20m |
| 2026-07-01 | UAL435 | - | Jul 1, 15:50 UTC | Jul 1, 20:40 UTC | 4h 50m |
| 2026-07-01 | UAL1346 | - | Jul 1, 08:30 UTC | Jul 1, 13:00 UTC | 4h 30m |
| 2026-07-01 | UAL200 | - | Jul 1, 03:45 UTC | Jul 1, 04:00 UTC | 15m |
| 2026-06-30 | UAL201 | - | Jun 30, 01:04 UTC | Jun 30, 01:14 UTC | 10m |
| 2026-06-29 | UAL1175 | - | Jun 29, 16:44 UTC | Jun 29, 21:24 UTC | 4h 40m |
| 2026-06-29 | UAL872 | - | Jun 29, 04:25 UTC | Jun 29, 13:04 UTC | 8h 40m |
| 2026-06-29 | UAL872 | - | Jun 29, 02:09 UTC | Jun 29, 02:20 UTC | 10m |
| 2026-06-27 | UAL871 | SFO → TPE | Jun 27, 22:08 UTC | Jun 28, 10:39 UTC | 12h 31m |
| 2026-06-27 | UAL871 | - | Jun 27, 22:04 UTC | Jun 27, 22:29 UTC | 25m |
| 2026-06-27 | UAL1960 | EWR → SFO | Jun 27, 11:14 UTC | Jun 27, 16:55 UTC | 5h 40m |
| 2026-06-26 | UAL78 | NRT → EWR | Jun 26, 09:00 UTC | Jun 26, 17:59 UTC | 9h 0m |
| 2026-06-26 | UAL78 | NRT → EWR | Jun 26, 08:51 UTC | Jun 26, 21:23 UTC | 12h 32m |
| 2026-06-26 | UAL78 | NRT → EWR | Jun 26, 08:51 UTC | Jun 26, 21:16 UTC | 12h 25m |
| 2026-06-25 | UAL837 | SFO → NRT | Jun 25, 20:09 UTC | Jun 26, 01:10 UTC | 5h 0m |
| 2026-06-25 | UAL837 | SFO → NRT | Jun 25, 19:57 UTC | Jun 26, 06:14 UTC | 10h 17m |
| 2026-06-25 | UAL862 | HKG → SFO | Jun 25, 04:11 UTC | Jun 25, 16:32 UTC | 12h 21m |
| 2026-06-25 | UAL862 | - | Jun 25, 04:04 UTC | Jun 25, 16:50 UTC | 12h 45m |
| 2026-06-25 | UAL862 | HKG → SFO | Jun 25, 04:11 UTC | Jun 25, 16:43 UTC | 12h 32m |
| 2026-06-24 | UAL877 | SFO → HKG | Jun 24, 07:20 UTC | Jun 24, 20:44 UTC | 13h 25m |
| 2026-06-23 | UAL878 | - | Jun 23, 14:49 UTC | Jun 24, 02:49 UTC | 12h 0m |
| 2026-06-22 | UAL869 | SFO → HKG | Jun 22, 22:27 UTC | Jun 23, 11:47 UTC | 13h 20m |
| 2026-06-22 | UAL869 | - | Jun 22, 22:24 UTC | Jun 22, 22:49 UTC | 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 N2644U page for operator, model, and routing details .