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
- 114
- Distinct callsigns
- 20
- Country
- US
- Last broadcast
- 3h ago
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 |
|---|---|---|---|
| UAL198 | United Airlines | 7 | 2026-05-28 |
| UAL152 | United Airlines | 7 | 2026-05-26 |
| UAL153 | United Airlines | 6 | 2026-05-27 |
| UAL2023 | United Airlines | 5 | 2026-05-05 |
| UAL199 | United Airlines | 5 | 2026-05-28 |
| UAL820 | United Airlines | 4 | 2026-04-24 |
| UAL78 | United Airlines | 4 | 2026-04-14 |
| UAL61 | United Airlines | 4 | 2026-05-09 |
| UAL2222 | United Airlines | 4 | 2026-04-17 |
| UAL187 | United Airlines | 4 | 2026-05-11 |
| UAL1321 | United Airlines | 4 | 2026-04-20 |
| UAL1011 | United Airlines | 4 | 2026-05-05 |
| UAL821 | United Airlines | 3 | 2026-04-24 |
| UAL772 | United Airlines | 3 | 2026-05-21 |
| UAL771 | United Airlines | 3 | 2026-05-20 |
| UAL761 | United Airlines | 3 | 2026-04-13 |
| UAL29 | United Airlines | 3 | 2026-04-30 |
| UAL2096 | United Airlines | 3 | 2026-04-15 |
| UAL188 | United Airlines | 3 | 2026-05-10 |
| UAL143 | United Airlines | 3 | 2026-04-14 |
Recent flights last 50
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-05-30 | UAL123 | ANC → ORD | May 30, 06:50 UTC | May 30, 08:05 UTC | 1h 15m |
| 2026-05-29 | UAL122 | IAD → LHR | May 29, 14:09 UTC | May 29, 20:10 UTC | 6h 1m |
| 2026-05-29 | UAL122 | IAD → LHR | May 29, 13:50 UTC | May 29, 20:10 UTC | 6h 20m |
| 2026-05-29 | UAL2303 | IAD → SAN | May 29, 06:25 UTC | May 29, 10:55 UTC | 4h 30m |
| 2026-05-29 | UAL2303 | IAD → SAN | May 29, 06:34 UTC | May 29, 10:55 UTC | 4h 21m |
| 2026-05-28 | UAL199 | PVG → LAX | May 28, 07:05 UTC | May 28, 23:55 UTC | 16h 50m |
| 2026-05-28 | UAL198 | LAX → PVG | May 28, 01:20 UTC | May 28, 23:55 UTC | 22h 35m |
| 2026-05-28 | UAL198 | LAX → PVG | May 28, 00:45 UTC | May 28, 23:15 UTC | 22h 30m |
| 2026-05-27 | UAL198 | LAX → PVG | May 27, 20:45 UTC | May 28, 14:55 UTC | 18h 10m |
| 2026-05-27 | UAL153 | HKG → LAX | May 27, 05:08 UTC | May 27, 17:46 UTC | 12h 38m |
| 2026-05-27 | UAL153 | HKG → LAX | May 27, 04:55 UTC | May 27, 05:14 UTC | 20m |
| 2026-05-27 | UAL153 | HKG → LAX | May 27, 02:14 UTC | May 27, 02:34 UTC | 20m |
| 2026-05-26 | UAL152 | LAX → HKG | May 26, 12:54 UTC | May 26, 13:10 UTC | 15m |
| 2026-05-26 | UAL152 | LAX → HKG | May 26, 12:49 UTC | May 26, 15:00 UTC | 2h 11m |
| 2026-05-25 | UAL152 | LAX → HKG | May 25, 20:04 UTC | May 25, 20:34 UTC | 30m |
| 2026-05-25 | UAL152 | LAX → HKG | May 25, 20:08 UTC | May 26, 10:25 UTC | 14h 17m |
| 2026-05-24 | UAL935 | LHR → LAX | May 24, 12:15 UTC | May 24, 21:45 UTC | 9h 30m |
| 2026-05-23 | UAL923 | LAX → LHR | May 23, 22:45 UTC | May 24, 08:35 UTC | 9h 50m |
| 2026-05-23 | UAL153 | HKG → LAX | May 23, 04:45 UTC | May 23, 17:55 UTC | 13h 10m |
| 2026-05-23 | UAL153 | HKG → LAX | May 23, 02:10 UTC | May 23, 02:25 UTC | 15m |
| 2026-05-23 | UAL153 | HKG → LAX | May 23, 00:19 UTC | May 23, 02:24 UTC | 2h 5m |
| 2026-05-22 | UAL152 | LAX → HKG | May 22, 13:50 UTC | May 22, 14:05 UTC | 15m |
| 2026-05-22 | UAL152 | LAX → HKG | May 22, 10:25 UTC | May 22, 10:40 UTC | 15m |
| 2026-05-21 | UAL152 | LAX → HKG | May 21, 20:25 UTC | May 22, 09:55 UTC | 13h 30m |
| 2026-05-21 | UAL772 | DEN → DFW | May 21, 05:20 UTC | May 21, 15:35 UTC | 10h 15m |
| 2026-05-20 | UAL772 | DEN → DFW | May 20, 17:20 UTC | May 21, 15:35 UTC | 22h 15m |
| 2026-05-20 | UAL772 | DEN → DFW | May 20, 16:55 UTC | May 21, 15:15 UTC | 22h 20m |
| 2026-05-20 | UAL771 | BNA → ORD | May 20, 07:20 UTC | May 21, 07:05 UTC | 23h 45m |
| 2026-05-20 | UAL771 | BNA → ORD | May 20, 06:55 UTC | May 20, 19:10 UTC | 12h 15m |
| 2026-05-20 | UAL771 | BNA → ORD | May 20, 06:24 UTC | May 20, 20:23 UTC | 13h 59m |
| 2026-05-19 | UAL199 | PVG → LAX | May 19, 12:31 UTC | May 19, 23:39 UTC | 11h 8m |
| 2026-05-18 | UAL198 | LAX → PVG | May 18, 20:15 UTC | May 19, 08:25 UTC | 12h 10m |
| 2026-05-18 | UAL33 | NRT → LAX | May 18, 08:01 UTC | May 18, 17:25 UTC | 9h 25m |
| 2026-05-17 | UAL32 | LAX → NRT | May 17, 18:01 UTC | May 18, 04:51 UTC | 10h 50m |
| 2026-05-16 | UAL199 | PVG → LAX | May 16, 13:35 UTC | May 16, 15:10 UTC | 1h 35m |
| 2026-05-16 | UAL199 | PVG → LAX | May 16, 12:31 UTC | May 16, 23:28 UTC | 10h 57m |
| 2026-05-16 | UAL199 | PVG → LAX | May 16, 01:20 UTC | May 16, 23:35 UTC | 22h 15m |
| 2026-05-15 | UAL198 | LAX → PVG | May 15, 23:30 UTC | May 16, 23:15 UTC | 23h 45m |
| 2026-05-15 | UAL198 | LAX → PVG | May 15, 20:25 UTC | May 16, 08:11 UTC | 11h 46m |
| 2026-05-15 | UAL198 | LAX → PVG | May 15, 20:08 UTC | May 16, 09:27 UTC | 13h 19m |
| 2026-05-15 | UAL33 | NRT → LAX | May 15, 08:00 UTC | May 15, 17:30 UTC | 9h 29m |
| 2026-05-14 | UAL7 | IAH → NRT | May 14, 16:15 UTC | May 15, 04:35 UTC | 12h 20m |
| 2026-05-14 | UAL63 | GRU → IAH | May 14, 12:50 UTC | May 14, 13:10 UTC | 20m |
| 2026-05-14 | UAL63 | GRU → IAH | May 14, 03:30 UTC | May 14, 11:50 UTC | 8h 20m |
| 2026-05-13 | UAL62 | IAH → GRU | May 13, 00:10 UTC | May 13, 09:30 UTC | 9h 20m |
| 2026-05-13 | UAL62 | IAH → GRU | May 13, 00:03 UTC | May 13, 09:19 UTC | 9h 16m |
| 2026-05-12 | UAL6 | NRT → IAH | May 12, 08:10 UTC | May 12, 19:45 UTC | 11h 35m |
| 2026-05-11 | UAL79 | EWR → NRT | May 11, 16:25 UTC | May 12, 05:30 UTC | 13h 5m |
| 2026-05-11 | UAL187 | JNB → EWR | May 11, 12:40 UTC | May 11, 13:15 UTC | 35m |
| 2026-05-10 | UAL187 | JNB → EWR | May 10, 21:35 UTC | May 11, 00:40 UTC | 3h 5m |
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 .