sensors Mode-S transponder
A87223
ICAO 24-bit transponder address · allocated to United States
Currently assigned to N643UA · BOEING 767-300 · operated by UNITED AIRLINES INC
- Hex
- A87223
- Octal
- 52071043
- Decimal
- 11,039,267
- Country
- US
- Tail
- N643UA
- Type
- B763
- Flights observed
- 59
- Distinct callsigns
- 17
- Country
- US
- Last broadcast
- 58m ago
Current position
Country allocation
The ICAO 24-bit address A87223 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 17 distinct
| Callsign | Airline | Flights | Last seen |
|---|---|---|---|
| UAL20 | United Airlines | 9 | 2026-05-25 |
| UAL855 | United Airlines | 8 | 2026-05-20 |
| UAL854 | United Airlines | 6 | 2026-05-19 |
| UAL128 | United Airlines | 6 | 2026-05-16 |
| UAL947 | United Airlines | 5 | 2026-05-26 |
| UAL330 | United Airlines | 4 | 2026-04-17 |
| UAL129 | United Airlines | 4 | 2026-05-15 |
| UAL331 | United Airlines | 3 | 2026-04-17 |
| UAL21 | United Airlines | 3 | 2026-05-17 |
| UAL52 | United Airlines | 2 | 2026-05-27 |
| UAL3940 | United Airlines | 2 | 2026-05-21 |
| UAL2190 | United Airlines | 2 | 2026-05-20 |
| UAL946 | United Airlines | 1 | 2026-05-29 |
| UAL53 | United Airlines | 1 | 2026-05-28 |
| UAL3907 | United Airlines | 1 | 2026-04-29 |
| UAL3905 | United Airlines | 1 | 2026-05-24 |
| UAL1095 | United Airlines | 1 | 2026-04-18 |
Recent flights last 50
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-05-29 | UAL946 | IAD → AMS | May 29, 23:50 UTC | May 30, 00:45 UTC | 55m |
| 2026-05-28 | UAL53 | ZRH → IAD | May 28, 10:10 UTC | May 28, 18:35 UTC | 8h 25m |
| 2026-05-27 | UAL52 | IAD → ZRH | May 27, 22:10 UTC | May 28, 06:00 UTC | 7h 50m |
| 2026-05-27 | UAL52 | IAD → ZRH | May 27, 22:20 UTC | May 28, 04:45 UTC | 6h 25m |
| 2026-05-26 | UAL947 | AMS → IAD | May 26, 09:35 UTC | May 26, 17:34 UTC | 7h 59m |
| 2026-05-26 | UAL947 | AMS → IAD | May 26, 09:25 UTC | May 26, 17:35 UTC | 8h 10m |
| 2026-05-25 | UAL20 | IAH → AMS | May 25, 21:54 UTC | May 26, 06:49 UTC | 8h 55m |
| 2026-05-24 | UAL3905 | TPE → SFO | May 24, 13:40 UTC | May 24, 23:46 UTC | 10h 6m |
| 2026-05-21 | UAL20 | IAH → AMS | May 21, 21:50 UTC | May 22, 06:30 UTC | 8h 40m |
| 2026-05-21 | UAL3940 | DEN → SEA | May 21, 16:29 UTC | May 21, 19:39 UTC | 3h 10m |
| 2026-05-21 | UAL3940 | DEN → SEA | May 21, 16:35 UTC | May 21, 19:45 UTC | 3h 10m |
| 2026-05-20 | UAL2190 | EWR → MSP | May 20, 22:25 UTC | May 21, 01:50 UTC | 3h 25m |
| 2026-05-20 | UAL2190 | EWR → MSP | May 20, 22:37 UTC | May 21, 01:47 UTC | 3h 10m |
| 2026-05-20 | UAL855 | LIM → IAH | May 20, 06:35 UTC | May 20, 13:10 UTC | 6h 35m |
| 2026-05-20 | UAL855 | LIM → IAH | May 20, 06:18 UTC | May 20, 13:15 UTC | 6h 57m |
| 2026-05-19 | UAL854 | IAH → LIM | May 19, 22:30 UTC | May 20, 04:00 UTC | 5h 30m |
| 2026-05-17 | UAL21 | AMS → IAH | May 17, 09:20 UTC | May 17, 19:50 UTC | 10h 30m |
| 2026-05-16 | UAL20 | IAH → AMS | May 16, 21:35 UTC | May 17, 06:45 UTC | 9h 10m |
| 2026-05-16 | UAL20 | IAH → AMS | May 16, 21:42 UTC | May 17, 06:32 UTC | 8h 50m |
| 2026-05-16 | UAL128 | GIG → IAH | May 16, 01:25 UTC | May 16, 10:55 UTC | 9h 31m |
| 2026-05-16 | UAL128 | GIG → IAH | May 16, 00:25 UTC | May 16, 00:35 UTC | 10m |
| 2026-05-16 | UAL128 | GIG → IAH | May 16, 00:26 UTC | May 16, 10:46 UTC | 10h 20m |
| 2026-05-15 | UAL129 | IAH → GIG | May 15, 01:20 UTC | May 15, 10:30 UTC | 9h 10m |
| 2026-05-09 | UAL855 | LIM → IAH | May 9, 07:35 UTC | May 9, 13:30 UTC | 5h 55m |
| 2026-05-08 | UAL854 | IAH → LIM | May 8, 22:00 UTC | May 9, 03:35 UTC | 5h 35m |
| 2026-05-08 | UAL128 | GIG → IAH | May 8, 02:29 UTC | May 8, 10:19 UTC | 7h 50m |
| 2026-05-08 | UAL128 | GIG → IAH | May 8, 00:25 UTC | May 8, 00:34 UTC | 10m |
| 2026-05-07 | UAL129 | IAH → GIG | May 7, 01:50 UTC | May 7, 11:25 UTC | 9h 35m |
| 2026-05-06 | UAL21 | AMS → IAH | May 6, 11:55 UTC | May 6, 22:25 UTC | 10h 30m |
| 2026-05-05 | UAL20 | IAH → AMS | May 5, 22:25 UTC | May 6, 07:25 UTC | 9h 0m |
| 2026-05-05 | UAL855 | LIM → IAH | May 5, 06:45 UTC | May 5, 12:45 UTC | 6h 0m |
| 2026-05-04 | UAL854 | IAH → LIM | May 4, 22:25 UTC | May 5, 03:50 UTC | 5h 25m |
| 2026-05-04 | UAL854 | IAH → LIM | May 4, 22:17 UTC | May 5, 04:08 UTC | 5h 51m |
| 2026-05-04 | UAL128 | GIG → IAH | May 4, 01:44 UTC | May 4, 10:40 UTC | 8h 55m |
| 2026-05-03 | UAL129 | IAH → GIG | May 3, 02:35 UTC | May 3, 11:10 UTC | 8h 34m |
| 2026-05-03 | UAL129 | IAH → GIG | May 3, 01:35 UTC | May 3, 01:45 UTC | 10m |
| 2026-04-29 | UAL3907 | HKG → GUM | Apr 29, 08:15 UTC | Apr 29, 11:20 UTC | 3h 6m |
| 2026-04-18 | UAL1095 | MYR → EWR | Apr 18, 11:20 UTC | Apr 18, 16:30 UTC | 5h 10m |
| 2026-04-17 | UAL331 | CDG → IAD | Apr 17, 23:25 UTC | Apr 17, 23:35 UTC | 10m |
| 2026-04-17 | UAL331 | CDG → IAD | Apr 17, 21:50 UTC | Apr 17, 23:20 UTC | 1h 30m |
| 2026-04-17 | UAL331 | CDG → IAD | Apr 17, 15:24 UTC | Apr 17, 23:38 UTC | 8h 14m |
| 2026-04-17 | UAL330 | SFO → LAX | Apr 17, 09:20 UTC | Apr 17, 10:10 UTC | 50m |
| 2026-04-17 | UAL330 | SFO → LAX | Apr 17, 08:35 UTC | Apr 17, 09:15 UTC | 40m |
| 2026-04-17 | UAL330 | SFO → LAX | Apr 17, 03:20 UTC | Apr 17, 05:00 UTC | 1h 41m |
| 2026-04-17 | UAL330 | SFO → LAX | Apr 17, 03:10 UTC | Apr 17, 03:15 UTC | 5m |
| 2026-04-16 | UAL947 | AMS → IAD | Apr 16, 17:15 UTC | Apr 16, 17:44 UTC | 30m |
| 2026-04-16 | UAL947 | AMS → IAD | Apr 16, 15:30 UTC | Apr 16, 17:10 UTC | 1h 40m |
| 2026-04-16 | UAL947 | AMS → IAD | Apr 16, 09:35 UTC | Apr 16, 11:04 UTC | 1h 30m |
| 2026-04-16 | UAL20 | IAH → AMS | Apr 16, 05:24 UTC | Apr 16, 07:05 UTC | 1h 40m |
| 2026-04-16 | UAL20 | IAH → AMS | Apr 16, 01:10 UTC | Apr 16, 01:50 UTC | 40m |
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 N643UA page for operator, model, and routing details .