sensors Mode-S transponder
A31A57
ICAO 24-bit transponder address · allocated to United States
Currently assigned to N29978 · BOEING 787-9 Dreamliner · operated by UNITED AIRLINES INC
- Hex
- A31A57
- Octal
- 50615127
- Decimal
- 10,689,111
- Country
- US
- Tail
- N29978
- Type
- B789
- Flights observed
- 96
- Distinct callsigns
- 20
- Country
- US
- Last broadcast
- 5h ago
Last known position
Country allocation
The ICAO 24-bit address A31A57 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 |
|---|---|---|---|
| UAL893 | United Airlines | 9 | 2026-05-27 |
| UAL29 | United Airlines | 8 | 2026-04-27 |
| UAL28 | United Airlines | 8 | 2026-04-28 |
| UAL892 | United Airlines | 6 | 2026-05-28 |
| UAL935 | United Airlines | 5 | 2026-05-20 |
| UAL870 | United Airlines | 5 | 2026-05-27 |
| UAL60 | United Airlines | 5 | 2026-05-29 |
| UAL152 | United Airlines | 5 | 2026-05-05 |
| UAL923 | United Airlines | 4 | 2026-05-19 |
| UAL839 | United Airlines | 4 | 2026-05-26 |
| UAL821 | United Airlines | 3 | 2026-05-25 |
| UAL820 | United Airlines | 3 | 2026-05-25 |
| UAL61 | United Airlines | 3 | 2026-05-30 |
| UAL115 | United Airlines | 3 | 2026-05-01 |
| UAL114 | United Airlines | 3 | 2026-05-02 |
| UAL863 | United Airlines | 2 | 2026-04-16 |
| UAL842 | United Airlines | 2 | 2026-05-22 |
| UAL153 | United Airlines | 2 | 2026-05-06 |
| UAL83 | United Airlines | 1 | 2026-05-12 |
| UAL82 | United Airlines | 1 | 2026-05-12 |
Recent flights last 50
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-05-30 | UAL61 | BRU → EWR | May 30, 01:14 UTC | May 30, 14:37 UTC | 13h 23m |
| 2026-05-30 | UAL61 | BRU → EWR | May 30, 01:10 UTC | May 30, 01:45 UTC | 35m |
| 2026-05-29 | UAL60 | SFO → MEL | May 29, 06:57 UTC | May 29, 22:05 UTC | 15h 8m |
| 2026-05-29 | UAL60 | SFO → MEL | May 29, 07:05 UTC | May 29, 07:25 UTC | 20m |
| 2026-05-28 | UAL892 | ICN → SFO | May 28, 08:05 UTC | May 28, 18:25 UTC | 10h 20m |
| 2026-05-27 | UAL893 | SFO → ICN | May 27, 18:20 UTC | May 28, 05:55 UTC | 11h 35m |
| 2026-05-27 | UAL870 | SYD → SFO | May 27, 00:39 UTC | May 27, 13:55 UTC | 13h 16m |
| 2026-05-26 | UAL839 | LAX → SYD | May 26, 06:44 UTC | May 26, 20:54 UTC | 14h 10m |
| 2026-05-25 | UAL821 | SFO → MEX | May 25, 14:00 UTC | May 26, 03:15 UTC | 13h 15m |
| 2026-05-25 | UAL821 | SFO → MEX | May 25, 11:10 UTC | May 25, 11:30 UTC | 20m |
| 2026-05-25 | UAL821 | SFO → MEX | May 25, 09:05 UTC | May 25, 09:40 UTC | 35m |
| 2026-05-25 | UAL820 | MEX → SFO | May 25, 00:01 UTC | May 25, 02:20 UTC | 2h 19m |
| 2026-05-24 | UAL820 | MEX → SFO | May 24, 07:14 UTC | May 24, 21:19 UTC | 14h 5m |
| 2026-05-24 | UAL820 | MEX → SFO | May 24, 07:10 UTC | May 24, 21:15 UTC | 14h 5m |
| 2026-05-23 | UAL199 | PVG → LAX | May 23, 06:45 UTC | May 23, 23:50 UTC | 17h 5m |
| 2026-05-22 | UAL198 | LAX → PVG | May 22, 20:30 UTC | May 23, 14:40 UTC | 18h 9m |
| 2026-05-22 | UAL842 | SYD → LAX | May 22, 00:00 UTC | May 22, 12:50 UTC | 12h 50m |
| 2026-05-21 | UAL839 | LAX → SYD | May 21, 06:05 UTC | May 21, 21:10 UTC | 15h 5m |
| 2026-05-20 | UAL935 | LHR → LAX | May 20, 12:40 UTC | May 20, 22:50 UTC | 10h 10m |
| 2026-05-19 | UAL923 | LAX → LHR | May 19, 23:00 UTC | May 20, 08:55 UTC | 9h 56m |
| 2026-05-17 | UAL935 | LHR → LAX | May 17, 12:15 UTC | May 17, 22:25 UTC | 10h 10m |
| 2026-05-17 | UAL935 | LHR → LAX | May 17, 12:30 UTC | May 17, 22:21 UTC | 9h 51m |
| 2026-05-16 | UAL923 | LAX → LHR | May 16, 23:10 UTC | May 17, 08:55 UTC | 9h 45m |
| 2026-05-16 | UAL923 | LAX → LHR | May 16, 23:08 UTC | May 17, 08:54 UTC | 9h 46m |
| 2026-05-16 | UAL842 | SYD → LAX | May 16, 00:05 UTC | May 16, 13:01 UTC | 12h 56m |
| 2026-05-15 | UAL839 | LAX → SYD | May 15, 07:00 UTC | May 15, 21:35 UTC | 14h 34m |
| 2026-05-15 | UAL839 | LAX → SYD | May 15, 06:14 UTC | May 15, 21:29 UTC | 15h 15m |
| 2026-05-14 | UAL935 | LHR → LAX | May 14, 12:25 UTC | May 14, 23:00 UTC | 10h 35m |
| 2026-05-14 | UAL935 | LHR → LAX | May 14, 12:30 UTC | May 14, 22:56 UTC | 10h 26m |
| 2026-05-13 | UAL923 | LAX → LHR | May 13, 22:55 UTC | May 14, 08:45 UTC | 9h 50m |
| 2026-05-13 | UAL2692 | IAD → PHL | May 13, 13:45 UTC | May 13, 18:50 UTC | 5h 5m |
| 2026-05-12 | UAL83 | DEL → EWR | May 12, 18:35 UTC | May 13, 10:10 UTC | 15h 35m |
| 2026-05-12 | UAL82 | EWR → DEL | May 12, 05:55 UTC | May 12, 14:45 UTC | 8h 50m |
| 2026-05-11 | UAL78 | NRT → EWR | May 11, 08:35 UTC | May 11, 20:50 UTC | 12h 15m |
| 2026-05-10 | UAL7 | IAH → NRT | May 10, 15:39 UTC | May 11, 04:40 UTC | 13h 0m |
| 2026-05-10 | UAL63 | GRU → IAH | May 10, 02:20 UTC | May 10, 11:25 UTC | 9h 5m |
| 2026-05-09 | UAL62 | IAH → GRU | May 9, 00:20 UTC | May 9, 09:10 UTC | 8h 50m |
| 2026-05-08 | UAL6D | NRT → IAH | May 8, 08:14 UTC | May 8, 19:30 UTC | 11h 15m |
| 2026-05-07 | UAL79 | EWR → NRT | May 7, 15:45 UTC | May 8, 05:09 UTC | 13h 24m |
| 2026-05-06 | UAL1855 | ORD → BOS | May 6, 20:30 UTC | May 7, 00:35 UTC | 4h 5m |
| 2026-05-06 | UAL153 | HKG → LAX | May 6, 04:50 UTC | May 6, 17:50 UTC | 12h 59m |
| 2026-05-06 | UAL153 | HKG → LAX | May 6, 02:15 UTC | May 6, 02:20 UTC | 5m |
| 2026-05-05 | UAL152 | LAX → HKG | May 5, 13:00 UTC | May 5, 13:10 UTC | 10m |
| 2026-05-05 | UAL152 | LAX → HKG | May 5, 12:49 UTC | May 5, 15:04 UTC | 2h 15m |
| 2026-05-05 | UAL152 | LAX → HKG | May 5, 09:50 UTC | May 5, 10:10 UTC | 20m |
| 2026-05-04 | UAL152 | LAX → HKG | May 4, 19:15 UTC | May 5, 09:15 UTC | 14h 0m |
| 2026-05-04 | UAL152 | LAX → HKG | May 4, 19:17 UTC | May 5, 10:05 UTC | 14h 48m |
| 2026-05-03 | UAL1321 | MIA → EWR | May 3, 16:05 UTC | May 3, 21:24 UTC | 5h 20m |
| 2026-05-02 | UAL713 | ORD → DEL | May 2, 17:45 UTC | May 2, 22:25 UTC | 4h 40m |
| 2026-05-02 | UAL114 | PPT → SFO | May 2, 07:15 UTC | May 2, 14:45 UTC | 7h 30m |
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 N29978 page for operator, model, and routing details .