sensors Mode-S transponder
A31A2D
ICAO 24-bit transponder address · allocated to United States
Currently assigned to N29961 · BOEING 787-9 Dreamliner · operated by UNITED AIRLINES INC
- Hex
- A31A2D
- Octal
- 50615055
- Decimal
- 10,689,069
- Country
- US
- Tail
- N29961
- Type
- B789
- Flights observed
- 220
- Distinct callsigns
- 20
- Country
- US
- Last broadcast
- Jul 24, 19:40 UTC
Last known position
Country allocation
The ICAO 24-bit address A31A2D 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 |
|---|---|---|---|
| UAL2222 | - | 8 | 2026-06-26 |
| UAL198 | - | 8 | 2026-06-29 |
| UAL820 | - | 7 | 2026-06-16 |
| UAL2023 | - | 7 | 2026-07-17 |
| UAL152 | United Airlines | 7 | 2026-05-26 |
| UAL870 | - | 6 | 2026-07-01 |
| UAL821 | - | 6 | 2026-06-17 |
| UAL29 | United Airlines | 6 | 2026-07-22 |
| UAL28 | United Airlines | 6 | 2026-07-23 |
| UAL2096 | United Airlines | 6 | 2026-06-24 |
| UAL199 | United Airlines | 6 | 2026-06-29 |
| UAL153 | United Airlines | 6 | 2026-05-27 |
| UAL122 | - | 6 | 2026-07-03 |
| UAL1122 | - | 6 | 2026-06-25 |
| UAL1011 | - | 6 | 2026-07-17 |
| UAL62 | - | 5 | 2026-07-10 |
| UAL61 | United Airlines | 5 | 2026-06-03 |
| UAL187 | - | 5 | 2026-06-22 |
| UAL83 | United Airlines | 4 | 2026-07-05 |
| UAL78 | United Airlines | 4 | 2026-04-14 |
Recent flights last 50
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-07-24 | UAL3896 | IAH → EWR | Jul 24, 07:26 UTC | Jul 24, 19:20 UTC | 11h 54m |
| 2026-07-24 | UAL3896 | IAH → EWR | Jul 24, 07:25 UTC | Jul 24, 19:40 UTC | 12h 15m |
| 2026-07-23 | UAL28 | SIN → SFO | Jul 23, 16:30 UTC | Jul 24, 04:55 UTC | 12h 25m |
| 2026-07-23 | UAL28 | SIN → SFO | Jul 23, 13:36 UTC | Jul 24, 04:47 UTC | 15h 11m |
| 2026-07-22 | UAL29 | SFO → SIN | Jul 22, 19:50 UTC | Jul 23, 11:15 UTC | 15h 25m |
| 2026-07-21 | UAL114 | - | Jul 21, 07:10 UTC | Jul 21, 15:05 UTC | 7h 55m |
| 2026-07-20 | UAL115 | SFO → PPT | Jul 20, 21:15 UTC | Jul 21, 05:05 UTC | 7h 50m |
| 2026-07-19 | UAL1757 | IAD → SFO | Jul 19, 02:53 UTC | Jul 19, 07:31 UTC | 4h 38m |
| 2026-07-19 | UAL1757 | - | Jul 19, 02:55 UTC | Jul 19, 07:30 UTC | 4h 35m |
| 2026-07-17 | UAL2023 | - | Jul 17, 18:15 UTC | Jul 17, 18:34 UTC | 20m |
| 2026-07-17 | UAL2023 | BOS → ORD | Jul 17, 18:21 UTC | Jul 18, 09:04 UTC | 14h 43m |
| 2026-07-17 | UAL1011 | - | Jul 17, 12:30 UTC | Jul 17, 12:40 UTC | 10m |
| 2026-07-16 | UAL1011 | - | Jul 16, 23:05 UTC | Jul 16, 23:49 UTC | 45m |
| 2026-07-16 | UAL1849 | - | Jul 16, 15:45 UTC | Jul 16, 20:19 UTC | 4h 35m |
| 2026-07-16 | UAL3923 | DEN → SFO | Jul 16, 03:20 UTC | Jul 16, 06:05 UTC | 2h 45m |
| 2026-07-14 | UAL26 | - | Jul 14, 12:30 UTC | Jul 14, 21:00 UTC | 8h 30m |
| 2026-07-14 | UAL27 | DEN → LHR | Jul 14, 00:10 UTC | Jul 14, 08:40 UTC | 8h 30m |
| 2026-07-13 | UAL27 | DEN → LHR | Jul 13, 23:58 UTC | Jul 14, 08:28 UTC | 8h 30m |
| 2026-07-13 | UAL181 | - | Jul 13, 09:45 UTC | Jul 13, 19:15 UTC | 9h 30m |
| 2026-07-13 | UAL181 | FRA → DEN | Jul 13, 09:51 UTC | Jul 13, 19:11 UTC | 9h 20m |
| 2026-07-12 | UAL182 | DEN → FRA | Jul 12, 22:35 UTC | Jul 13, 07:35 UTC | 9h 0m |
| 2026-07-12 | UAL142 | - | Jul 12, 07:50 UTC | Jul 12, 08:20 UTC | 30m |
| 2026-07-12 | UAL142 | NRT → DEN | Jul 12, 07:50 UTC | Jul 12, 17:49 UTC | 9h 59m |
| 2026-07-12 | UAL142 | NRT → DEN | Jul 12, 07:50 UTC | Jul 12, 17:51 UTC | 10h 1m |
| 2026-07-11 | UAL7 | - | Jul 11, 16:15 UTC | Jul 12, 04:50 UTC | 12h 35m |
| 2026-07-11 | UAL63 | GRU → IAH | Jul 11, 01:11 UTC | Jul 11, 10:33 UTC | 9h 22m |
| 2026-07-10 | UAL62 | IAH → GRU | Jul 10, 00:03 UTC | Jul 10, 09:06 UTC | 9h 3m |
| 2026-07-09 | UAL62 | - | Jul 9, 23:55 UTC | Jul 10, 04:50 UTC | 4h 55m |
| 2026-07-09 | UAL6 | - | Jul 9, 08:20 UTC | Jul 9, 19:45 UTC | 11h 25m |
| 2026-07-09 | UAL6 | NRT → IAH | Jul 9, 08:26 UTC | Jul 9, 19:45 UTC | 11h 19m |
| 2026-07-08 | UAL32 | LAX → NRT | Jul 8, 18:15 UTC | Jul 9, 04:50 UTC | 10h 35m |
| 2026-07-08 | UAL32 | - | Jul 8, 18:15 UTC | Jul 9, 04:55 UTC | 10h 40m |
| 2026-07-08 | UAL99 | - | Jul 8, 00:00 UTC | Jul 8, 13:30 UTC | 13h 30m |
| 2026-07-07 | UAL98 | LAX → MEL | Jul 7, 06:20 UTC | Jul 7, 21:40 UTC | 15h 20m |
| 2026-07-06 | UAL2692 | EWR → LAX | Jul 6, 13:49 UTC | Jul 6, 18:25 UTC | 4h 36m |
| 2026-07-06 | UAL2692 | - | Jul 6, 13:35 UTC | Jul 6, 18:30 UTC | 4h 55m |
| 2026-07-05 | UAL83 | DEL → EWR | Jul 5, 18:25 UTC | Jul 5, 19:00 UTC | 35m |
| 2026-07-05 | UAL83 | DEL → EWR | Jul 5, 18:32 UTC | Jul 6, 10:07 UTC | 15h 35m |
| 2026-07-05 | UAL82 | EWR → DEL | Jul 5, 01:44 UTC | Jul 5, 15:28 UTC | 13h 44m |
| 2026-07-05 | UAL82 | - | Jul 5, 01:40 UTC | Jul 5, 11:55 UTC | 10h 15m |
| 2026-07-04 | UAL123 | - | Jul 4, 07:00 UTC | Jul 4, 14:10 UTC | 7h 10m |
| 2026-07-04 | UAL123 | LHR → EWR | Jul 4, 06:52 UTC | Jul 4, 14:05 UTC | 7h 13m |
| 2026-07-03 | UAL122 | EWR → LHR | Jul 3, 15:05 UTC | Jul 3, 21:20 UTC | 6h 15m |
| 2026-07-03 | UAL122 | EWR → LHR | Jul 3, 14:09 UTC | Jul 3, 21:15 UTC | 7h 6m |
| 2026-07-02 | UAL83 | DEL → EWR | Jul 2, 18:40 UTC | Jul 3, 10:25 UTC | 15h 45m |
| 2026-07-02 | UAL83 | DEL → EWR | Jul 2, 18:36 UTC | Jul 3, 10:17 UTC | 15h 41m |
| 2026-07-02 | UAL82 | EWR → DEL | Jul 2, 02:30 UTC | Jul 2, 16:15 UTC | 13h 45m |
| 2026-07-01 | UAL713 | - | Jul 1, 17:55 UTC | Jul 1, 22:35 UTC | 4h 40m |
| 2026-07-01 | UAL870 | - | Jul 1, 01:15 UTC | Jul 1, 13:55 UTC | 12h 40m |
| 2026-06-30 | UAL839 | - | Jun 30, 07:15 UTC | Jun 30, 21:40 UTC | 14h 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 N29961 page for operator, model, and routing details .