sensors Mode-S transponder
A2CB12
ICAO 24-bit transponder address · allocated to United States
Currently assigned to N27957 · BOEING 787-9 Dreamliner · operated by UNITED AIRLINES INC
- Hex
- A2CB12
- Octal
- 50545422
- Decimal
- 10,668,818
- Country
- US
- Tail
- N27957
- Type
- B789
- Flights observed
- 110
- Distinct callsigns
- 20
- Country
- US
- Last broadcast
- 4h ago
Last known position
Country allocation
The ICAO 24-bit address A2CB12 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 |
|---|---|---|---|
| UAL83 | United Airlines | 6 | 2026-04-15 |
| UAL62 | United Airlines | 6 | 2026-05-07 |
| UAL82 | United Airlines | 5 | 2026-04-14 |
| UAL713 | United Airlines | 5 | 2026-04-25 |
| UAL7 | United Airlines | 5 | 2026-05-08 |
| UAL6 | United Airlines | 5 | 2026-05-06 |
| UAL1960 | United Airlines | 5 | 2026-04-21 |
| UAL1757 | United Airlines | 5 | 2026-04-23 |
| UAL262 | United Airlines | 4 | 2026-05-19 |
| UAL1849 | United Airlines | 4 | 2026-04-23 |
| UAL935 | United Airlines | 3 | 2026-05-23 |
| UAL923 | United Airlines | 3 | 2026-05-22 |
| UAL79 | United Airlines | 3 | 2026-05-02 |
| UAL78 | United Airlines | 3 | 2026-05-09 |
| UAL63 | United Airlines | 3 | 2026-05-08 |
| UAL435 | United Airlines | 3 | 2026-04-17 |
| UAL1227 | United Airlines | 3 | 2026-04-15 |
| UAL839 | United Airlines | 2 | 2026-05-28 |
| UAL772 | United Airlines | 2 | 2026-05-25 |
| UAL771 | United Airlines | 2 | 2026-05-24 |
Recent flights last 50
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-05-29 | UAL29 | SFO → SIN | May 29, 18:40 UTC | May 29, 19:35 UTC | 55m |
| 2026-05-29 | UAL870 | SYD → SFO | May 29, 00:45 UTC | May 29, 14:05 UTC | 13h 20m |
| 2026-05-28 | UAL839 | LAX → SYD | May 28, 06:09 UTC | May 28, 21:32 UTC | 15h 23m |
| 2026-05-28 | UAL839 | LAX → SYD | May 28, 06:40 UTC | May 28, 21:35 UTC | 14h 55m |
| 2026-05-25 | UAL772 | DEN → DFW | May 25, 05:10 UTC | May 25, 06:30 UTC | 1h 20m |
| 2026-05-25 | UAL772 | DEN → DFW | May 25, 04:29 UTC | May 25, 15:52 UTC | 11h 23m |
| 2026-05-24 | UAL771 | BNA → ORD | May 24, 06:50 UTC | May 24, 19:25 UTC | 12h 35m |
| 2026-05-24 | UAL771 | BNA → ORD | May 24, 06:54 UTC | May 24, 20:35 UTC | 13h 41m |
| 2026-05-23 | UAL935 | LHR → LAX | May 23, 12:35 UTC | May 23, 23:00 UTC | 10h 26m |
| 2026-05-23 | UAL935 | LHR → LAX | May 23, 12:30 UTC | May 23, 22:52 UTC | 10h 22m |
| 2026-05-22 | UAL923 | LAX → LHR | May 22, 22:50 UTC | May 23, 08:50 UTC | 9h 59m |
| 2026-05-22 | UAL923 | LAX → LHR | May 22, 22:53 UTC | May 23, 08:48 UTC | 9h 55m |
| 2026-05-22 | UAL33 | NRT → LAX | May 22, 11:05 UTC | May 22, 20:00 UTC | 8h 55m |
| 2026-05-21 | UAL143 | DEN → NRT | May 21, 21:00 UTC | May 22, 08:10 UTC | 11h 10m |
| 2026-05-20 | UAL761 | MUC → DEN | May 20, 14:40 UTC | May 21, 00:40 UTC | 10h 0m |
| 2026-05-20 | UAL760 | DEN → MUC | May 20, 02:50 UTC | May 20, 11:50 UTC | 9h 1m |
| 2026-05-19 | UAL263 | EWR → PBI | May 19, 14:30 UTC | May 19, 23:35 UTC | 9h 5m |
| 2026-05-19 | UAL262 | DEN → LHR | May 19, 02:58 UTC | May 19, 11:11 UTC | 8h 13m |
| 2026-05-19 | UAL262 | DEN → LHR | May 19, 03:05 UTC | May 19, 04:30 UTC | 1h 25m |
| 2026-05-18 | UAL263 | EWR → PBI | May 18, 14:50 UTC | May 19, 00:20 UTC | 9h 29m |
| 2026-05-18 | UAL262 | DEN → LHR | May 18, 03:01 UTC | May 18, 11:59 UTC | 8h 58m |
| 2026-05-18 | UAL262 | DEN → LHR | May 18, 03:20 UTC | May 18, 04:30 UTC | 1h 10m |
| 2026-05-17 | UAL178 | KIX → GUM | May 17, 12:45 UTC | May 17, 23:40 UTC | 10h 55m |
| 2026-05-16 | UAL177 | GUM → KIX | May 16, 23:45 UTC | May 17, 09:50 UTC | 10h 5m |
| 2026-05-16 | UAL26 | LHR → DEN | May 16, 11:55 UTC | May 16, 20:40 UTC | 8h 45m |
| 2026-05-16 | UAL27 | DEN → LHR | May 16, 01:40 UTC | May 16, 09:40 UTC | 8h 1m |
| 2026-05-15 | UAL181 | FRA → DEN | May 15, 09:45 UTC | May 15, 19:25 UTC | 9h 39m |
| 2026-05-14 | UAL182 | DEN → FRA | May 14, 22:08 UTC | May 15, 06:34 UTC | 8h 26m |
| 2026-05-14 | UAL182 | DEN → FRA | May 14, 21:55 UTC | May 15, 06:40 UTC | 8h 45m |
| 2026-05-14 | UAL142 | NRT → DEN | May 14, 07:55 UTC | May 14, 18:00 UTC | 10h 5m |
| 2026-05-14 | UAL142 | NRT → DEN | May 14, 07:50 UTC | May 14, 17:59 UTC | 10h 9m |
| 2026-05-13 | UAL32 | LAX → NRT | May 13, 17:55 UTC | May 14, 04:45 UTC | 10h 50m |
| 2026-05-13 | UAL32 | LAX → NRT | May 13, 17:50 UTC | May 14, 04:45 UTC | 10h 55m |
| 2026-05-11 | UAL935 | LHR → LAX | May 11, 12:15 UTC | May 11, 22:35 UTC | 10h 20m |
| 2026-05-10 | UAL923 | LAX → LHR | May 10, 23:00 UTC | May 11, 09:00 UTC | 10h 0m |
| 2026-05-10 | UAL2692 | IAD → PHL | May 10, 13:49 UTC | May 10, 19:00 UTC | 5h 10m |
| 2026-05-09 | UAL78 | NRT → EWR | May 9, 08:40 UTC | May 9, 09:05 UTC | 25m |
| 2026-05-09 | UAL78 | NRT → EWR | May 9, 08:51 UTC | May 9, 20:20 UTC | 11h 29m |
| 2026-05-08 | UAL7 | IAH → NRT | May 8, 15:40 UTC | May 9, 05:00 UTC | 13h 20m |
| 2026-05-08 | UAL7 | IAH → NRT | May 8, 15:32 UTC | May 9, 05:00 UTC | 13h 28m |
| 2026-05-08 | UAL63 | GRU → IAH | May 8, 01:14 UTC | May 8, 10:25 UTC | 9h 10m |
| 2026-05-07 | UAL62 | IAH → GRU | May 7, 05:10 UTC | May 7, 09:35 UTC | 4h 25m |
| 2026-05-07 | UAL62 | IAH → GRU | May 7, 00:20 UTC | May 7, 00:35 UTC | 15m |
| 2026-05-07 | UAL62 | IAH → GRU | May 7, 00:23 UTC | May 7, 09:24 UTC | 9h 1m |
| 2026-05-06 | UAL6 | NRT → IAH | May 6, 08:15 UTC | May 6, 08:30 UTC | 15m |
| 2026-05-06 | UAL6 | NRT → IAH | May 6, 08:26 UTC | May 6, 19:28 UTC | 11h 2m |
| 2026-05-05 | UAL7 | IAH → NRT | May 5, 15:35 UTC | May 6, 05:00 UTC | 13h 25m |
| 2026-05-05 | UAL63 | GRU → IAH | May 5, 01:15 UTC | May 5, 10:30 UTC | 9h 15m |
| 2026-05-04 | UAL62 | IAH → GRU | May 4, 01:15 UTC | May 4, 09:40 UTC | 8h 25m |
| 2026-05-04 | UAL62 | IAH → GRU | May 4, 00:15 UTC | May 4, 00:30 UTC | 15m |
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 N27957 page for operator, model, and routing details .