sensors Mode-S transponder
A2B8FE
ICAO 24-bit transponder address · allocated to United States
Currently assigned to N2749U · BOEING 777-300ER · operated by UNITED AIRLINES INC
- Hex
- A2B8FE
- Octal
- 50534376
- Decimal
- 10,664,190
- Country
- US
- Tail
- N2749U
- Type
- B77W
- Flights observed
- 107
- Distinct callsigns
- 20
- Country
- US
- Last broadcast
- 3h ago
Last known position
Country allocation
The ICAO 24-bit address A2B8FE 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 | United Airlines | 11 | 2026-05-27 |
| UAL809 | United Airlines | 10 | 2026-05-29 |
| UAL877 | United Airlines | 9 | 2026-05-28 |
| UAL858 | United Airlines | 9 | 2026-05-26 |
| UAL872 | United Airlines | 7 | 2026-05-23 |
| UAL862 | United Airlines | 7 | 2026-05-29 |
| UAL857 | United Airlines | 6 | 2026-05-24 |
| UAL871 | United Airlines | 5 | 2026-05-22 |
| UAL838 | United Airlines | 5 | 2026-05-24 |
| UAL988 | United Airlines | 4 | 2026-04-17 |
| UAL878 | United Airlines | 4 | 2026-05-16 |
| UAL869 | United Airlines | 4 | 2026-05-15 |
| UAL837 | United Airlines | 4 | 2026-05-23 |
| UAL803 | United Airlines | 3 | 2026-04-14 |
| UAL42 | United Airlines | 3 | 2026-04-17 |
| UAL1149 | United Airlines | 3 | 2026-04-16 |
| UAL989 | United Airlines | 2 | 2026-04-20 |
| UAL876 | United Airlines | 2 | 2026-04-14 |
| UAL3902 | United Airlines | 2 | 2026-04-22 |
| UAL951 | United Airlines | 1 | 2026-04-20 |
Recent flights last 50
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-05-29 | UAL809 | SEA → IAD | May 29, 22:00 UTC | May 29, 22:20 UTC | 20m |
| 2026-05-29 | UAL862 | HKG → SFO | May 29, 03:55 UTC | May 29, 16:15 UTC | 12h 20m |
| 2026-05-28 | UAL877 | SFO → HKG | May 28, 07:21 UTC | May 28, 20:33 UTC | 13h 12m |
| 2026-05-28 | UAL877 | SFO → HKG | May 28, 07:10 UTC | May 28, 07:30 UTC | 20m |
| 2026-05-27 | UAL810 | PHL → DEN | May 27, 13:56 UTC | May 28, 02:16 UTC | 12h 20m |
| 2026-05-27 | UAL810 | PHL → DEN | May 27, 13:55 UTC | May 28, 02:15 UTC | 12h 20m |
| 2026-05-27 | UAL810 | PHL → DEN | May 27, 13:56 UTC | May 28, 02:10 UTC | 12h 14m |
| 2026-05-26 | UAL809 | SEA → IAD | May 26, 22:09 UTC | May 27, 11:30 UTC | 13h 20m |
| 2026-05-26 | UAL858 | ICN → SFO | May 26, 04:44 UTC | May 26, 16:08 UTC | 11h 24m |
| 2026-05-26 | UAL858 | ICN → SFO | May 26, 04:44 UTC | May 26, 16:07 UTC | 11h 23m |
| 2026-05-25 | UAL858 | ICN → SFO | May 25, 07:35 UTC | May 26, 07:29 UTC | 23h 54m |
| 2026-05-24 | UAL857 | ICN → PVG | May 24, 20:55 UTC | May 25, 08:05 UTC | 11h 10m |
| 2026-05-24 | UAL838 | NRT → SFO | May 24, 08:25 UTC | May 24, 17:20 UTC | 8h 55m |
| 2026-05-23 | UAL837 | SFO → NRT | May 23, 19:55 UTC | May 24, 05:55 UTC | 10h 0m |
| 2026-05-23 | UAL872 | TPE → SFO | May 23, 13:05 UTC | May 23, 13:40 UTC | 35m |
| 2026-05-23 | UAL872 | TPE → SFO | May 23, 02:30 UTC | May 23, 02:45 UTC | 15m |
| 2026-05-22 | UAL871 | SFO → TPE | May 22, 10:50 UTC | May 22, 11:05 UTC | 15m |
| 2026-05-21 | UAL871 | SFO → TPE | May 21, 22:20 UTC | May 22, 09:30 UTC | 11h 10m |
| 2026-05-21 | UAL858 | ICN → SFO | May 21, 04:44 UTC | May 21, 15:12 UTC | 10h 28m |
| 2026-05-21 | UAL858 | ICN → SFO | May 21, 05:25 UTC | May 21, 15:15 UTC | 9h 50m |
| 2026-05-20 | UAL858 | ICN → SFO | May 20, 07:35 UTC | May 21, 06:45 UTC | 23h 10m |
| 2026-05-20 | UAL857 | ICN → PVG | May 20, 06:15 UTC | May 21, 05:30 UTC | 23h 15m |
| 2026-05-19 | UAL857 | ICN → PVG | May 19, 20:30 UTC | May 19, 20:55 UTC | 25m |
| 2026-05-19 | UAL857 | ICN → PVG | May 19, 20:22 UTC | May 20, 08:58 UTC | 12h 36m |
| 2026-05-19 | UAL838 | NRT → SFO | May 19, 08:30 UTC | May 19, 17:05 UTC | 8h 35m |
| 2026-05-19 | UAL838 | NRT → SFO | May 19, 08:31 UTC | May 19, 16:57 UTC | 8h 26m |
| 2026-05-18 | UAL837 | SFO → NRT | May 18, 19:05 UTC | May 19, 05:45 UTC | 10h 40m |
| 2026-05-18 | UAL862 | HKG → SFO | May 18, 03:50 UTC | May 18, 15:50 UTC | 12h 0m |
| 2026-05-17 | UAL877 | SFO → HKG | May 17, 06:31 UTC | May 17, 20:34 UTC | 14h 3m |
| 2026-05-17 | UAL877 | SFO → HKG | May 17, 06:30 UTC | May 17, 06:50 UTC | 20m |
| 2026-05-16 | UAL878 | HKG → SFO | May 16, 14:41 UTC | May 17, 03:00 UTC | 12h 20m |
| 2026-05-15 | UAL869 | SFO → HKG | May 15, 20:40 UTC | May 16, 10:46 UTC | 14h 6m |
| 2026-05-15 | UAL862 | HKG → SFO | May 15, 05:45 UTC | May 15, 17:35 UTC | 11h 49m |
| 2026-05-14 | UAL877 | SFO → HKG | May 14, 06:50 UTC | May 14, 21:30 UTC | 14h 40m |
| 2026-05-14 | UAL877 | SFO → HKG | May 14, 07:20 UTC | May 14, 21:30 UTC | 14h 10m |
| 2026-05-14 | UAL810 | PHL → DEN | May 14, 01:00 UTC | May 14, 01:40 UTC | 40m |
| 2026-05-13 | UAL810 | PHL → DEN | May 13, 13:35 UTC | May 13, 13:55 UTC | 20m |
| 2026-05-12 | UAL809 | SEA → IAD | May 12, 21:25 UTC | May 13, 10:45 UTC | 13h 20m |
| 2026-05-11 | UAL878 | HKG → SFO | May 11, 14:51 UTC | May 12, 03:07 UTC | 12h 16m |
| 2026-05-11 | UAL878 | HKG → SFO | May 11, 14:45 UTC | May 11, 17:30 UTC | 2h 46m |
| 2026-05-10 | UAL869 | SFO → HKG | May 10, 20:22 UTC | May 11, 10:49 UTC | 14h 27m |
| 2026-05-10 | UAL869 | SFO → HKG | May 10, 20:30 UTC | May 10, 20:54 UTC | 25m |
| 2026-05-10 | UAL858 | ICN → SFO | May 10, 05:20 UTC | May 10, 14:45 UTC | 9h 25m |
| 2026-05-10 | UAL858 | ICN → SFO | May 10, 04:44 UTC | May 10, 14:43 UTC | 9h 59m |
| 2026-05-09 | UAL858 | ICN → SFO | May 9, 07:35 UTC | May 10, 06:35 UTC | 23h 0m |
| 2026-05-09 | UAL857 | ICN → PVG | May 9, 06:30 UTC | May 10, 05:30 UTC | 23h 0m |
| 2026-05-08 | UAL857 | ICN → PVG | May 8, 20:40 UTC | May 9, 08:25 UTC | 11h 45m |
| 2026-05-08 | UAL872 | TPE → SFO | May 8, 03:30 UTC | May 8, 12:44 UTC | 9h 15m |
| 2026-05-08 | UAL872 | TPE → SFO | May 8, 02:23 UTC | May 8, 12:44 UTC | 10h 21m |
| 2026-05-08 | UAL872 | TPE → SFO | May 8, 02:04 UTC | May 8, 02:14 UTC | 10m |
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 N2749U page for operator, model, and routing details .