sensors Mode-S transponder
A31A50
ICAO 24-bit transponder address · allocated to United States
Currently assigned to N29971 · BOEING 787-9 Dreamliner · operated by UNITED AIRLINES INC
- Hex
- A31A50
- Octal
- 50615120
- Decimal
- 10,689,104
- Country
- US
- Tail
- N29971
- Type
- B789
- Flights observed
- 214
- Distinct callsigns
- 20
- Country
- US
- Last broadcast
- Jul 26, 21:30 UTC
Last known position
Country allocation
The ICAO 24-bit address A31A50 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 |
|---|---|---|---|
| UAL27 | - | 8 | 2026-06-25 |
| UAL262 | - | 8 | 2026-06-29 |
| UAL153 | United Airlines | 8 | 2026-05-30 |
| UAL33 | - | 7 | 2026-07-05 |
| UAL152 | United Airlines | 7 | 2026-05-29 |
| UAL32 | United Airlines | 6 | 2026-06-01 |
| UAL263 | - | 6 | 2026-06-29 |
| UAL26 | - | 6 | 2026-06-26 |
| UAL935 | United Airlines | 5 | 2026-05-31 |
| UAL79 | United Airlines | 5 | 2026-04-30 |
| UAL923 | - | 4 | 2026-07-05 |
| UAL892 | - | 4 | 2026-06-22 |
| UAL863 | United Airlines | 4 | 2026-07-24 |
| UAL842 | United Airlines | 4 | 2026-07-25 |
| UAL820 | United Airlines | 4 | 2026-07-26 |
| UAL805 | - | 4 | 2026-06-19 |
| UAL62 | - | 4 | 2026-07-03 |
| UAL61 | United Airlines | 4 | 2026-04-28 |
| UAL2222 | - | 4 | 2026-07-11 |
| UAL1855 | United Airlines | 4 | 2026-05-17 |
Recent flights last 50
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-07-26 | UAL820 | MEX → SFO | Jul 26, 07:40 UTC | Jul 26, 21:20 UTC | 13h 40m |
| 2026-07-25 | UAL353 | SAN → EWR | Jul 25, 23:35 UTC | Jul 26, 04:30 UTC | 4h 55m |
| 2026-07-25 | UAL2096 | LAX → EWR | Jul 25, 16:05 UTC | Jul 25, 20:40 UTC | 4h 35m |
| 2026-07-25 | UAL842 | SYD → LAX | Jul 25, 00:05 UTC | Jul 25, 13:10 UTC | 13h 5m |
| 2026-07-24 | UAL842 | SYD → LAX | Jul 24, 23:51 UTC | Jul 25, 13:05 UTC | 13h 14m |
| 2026-07-24 | UAL863 | SFO → SYD | Jul 24, 06:45 UTC | Jul 24, 20:50 UTC | 14h 5m |
| 2026-07-23 | UAL870 | SYD → SFO | Jul 23, 01:20 UTC | Jul 23, 14:10 UTC | 12h 50m |
| 2026-07-22 | UAL839 | LAX → SYD | Jul 22, 19:00 UTC | Jul 22, 22:00 UTC | 3h 0m |
| 2026-07-22 | UAL839 | LAX → SYD | Jul 22, 07:24 UTC | Jul 22, 21:58 UTC | 14h 34m |
| 2026-07-21 | UAL199 | - | Jul 21, 06:20 UTC | Jul 22, 01:15 UTC | 18h 55m |
| 2026-07-20 | UAL198 | LAX → PVG | Jul 20, 20:30 UTC | Jul 21, 15:55 UTC | 19h 24m |
| 2026-07-18 | UAL99 | - | Jul 18, 23:55 UTC | Jul 19, 14:05 UTC | 14h 10m |
| 2026-07-18 | UAL98 | - | Jul 18, 07:05 UTC | Jul 18, 21:45 UTC | 14h 40m |
| 2026-07-17 | UAL199 | PVG → LAX | Jul 17, 12:31 UTC | Jul 18, 00:12 UTC | 11h 41m |
| 2026-07-16 | UAL198 | - | Jul 16, 20:39 UTC | Jul 17, 15:00 UTC | 18h 20m |
| 2026-07-16 | UAL772 | - | Jul 16, 05:05 UTC | Jul 16, 16:25 UTC | 11h 20m |
| 2026-07-15 | UAL771 | - | Jul 15, 06:50 UTC | Jul 15, 18:55 UTC | 12h 5m |
| 2026-07-14 | UAL821 | HKG → LAX | Jul 14, 14:00 UTC | Jul 15, 03:05 UTC | 13h 4m |
| 2026-07-14 | UAL821 | - | Jul 14, 11:15 UTC | Jul 14, 11:35 UTC | 20m |
| 2026-07-14 | UAL821 | - | Jul 14, 09:10 UTC | Jul 14, 09:30 UTC | 20m |
| 2026-07-14 | UAL820 | - | Jul 14, 02:15 UTC | Jul 14, 02:30 UTC | 15m |
| 2026-07-14 | UAL820 | - | Jul 14, 00:20 UTC | Jul 14, 00:30 UTC | 10m |
| 2026-07-13 | UAL820 | - | Jul 13, 07:40 UTC | Jul 13, 21:25 UTC | 13h 45m |
| 2026-07-12 | UAL353 | - | Jul 12, 23:10 UTC | Jul 13, 03:50 UTC | 4h 40m |
| 2026-07-11 | UAL2222 | CPT → EWR | Jul 11, 18:12 UTC | Jul 12, 08:29 UTC | 14h 17m |
| 2026-07-11 | UAL2222 | - | Jul 11, 17:55 UTC | Jul 12, 08:30 UTC | 14h 35m |
| 2026-07-11 | UAL1122 | - | Jul 11, 15:00 UTC | Jul 11, 15:15 UTC | 15m |
| 2026-07-11 | UAL1122 | - | Jul 11, 01:20 UTC | Jul 11, 01:55 UTC | 35m |
| 2026-07-09 | UAL83 | DEL → EWR | Jul 9, 18:35 UTC | Jul 9, 19:15 UTC | 40m |
| 2026-07-09 | UAL83 | DEL → EWR | Jul 9, 18:37 UTC | Jul 10, 10:22 UTC | 15h 45m |
| 2026-07-09 | UAL82 | - | Jul 9, 02:10 UTC | Jul 9, 16:05 UTC | 13h 55m |
| 2026-07-08 | UAL2096 | LAX → EWR | Jul 8, 15:45 UTC | Jul 8, 20:15 UTC | 4h 30m |
| 2026-07-08 | UAL842 | SYD → LAX | Jul 8, 00:06 UTC | Jul 8, 12:44 UTC | 12h 38m |
| 2026-07-08 | UAL842 | - | Jul 8, 00:05 UTC | Jul 8, 12:45 UTC | 12h 40m |
| 2026-07-07 | UAL863 | SFO → SYD | Jul 7, 06:38 UTC | Jul 7, 21:02 UTC | 14h 24m |
| 2026-07-07 | UAL863 | SFO → SYD | Jul 7, 06:35 UTC | Jul 7, 21:00 UTC | 14h 25m |
| 2026-07-06 | UAL949 | - | Jul 6, 12:30 UTC | Jul 6, 15:00 UTC | 2h 30m |
| 2026-07-06 | UAL949 | LHR → SFO | Jul 6, 12:25 UTC | Jul 6, 22:47 UTC | 10h 22m |
| 2026-07-05 | UAL923 | - | Jul 5, 23:05 UTC | Jul 6, 09:00 UTC | 9h 55m |
| 2026-07-05 | UAL33 | - | Jul 5, 08:00 UTC | Jul 5, 17:35 UTC | 9h 35m |
| 2026-07-05 | UAL33 | NRT → LAX | Jul 5, 08:05 UTC | Jul 5, 17:29 UTC | 9h 24m |
| 2026-07-04 | UAL7 | - | Jul 4, 15:45 UTC | Jul 5, 04:30 UTC | 12h 45m |
| 2026-07-04 | UAL63 | - | Jul 4, 01:10 UTC | Jul 4, 10:35 UTC | 9h 25m |
| 2026-07-03 | UAL62 | - | Jul 3, 00:05 UTC | Jul 3, 09:30 UTC | 9h 25m |
| 2026-07-02 | UAL6 | - | Jul 2, 08:25 UTC | Jul 2, 19:20 UTC | 10h 55m |
| 2026-07-01 | UAL143 | DEN → NRT | Jul 1, 18:00 UTC | Jul 2, 05:05 UTC | 11h 5m |
| 2026-06-30 | UAL761 | MUC → DEN | Jun 30, 14:40 UTC | Jul 1, 00:55 UTC | 10h 15m |
| 2026-06-30 | UAL760 | DEN → MUC | Jun 30, 02:50 UTC | Jun 30, 12:00 UTC | 9h 10m |
| 2026-06-29 | UAL263 | - | Jun 29, 14:29 UTC | Jun 29, 23:39 UTC | 9h 10m |
| 2026-06-29 | UAL263 | LHR → DEN | Jun 29, 14:14 UTC | Jun 29, 23:32 UTC | 9h 18m |
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 N29971 page for operator, model, and routing details .