sensors Mode-S transponder
A1D8FD
ICAO 24-bit transponder address · allocated to United States
Currently assigned to N218UA · BOEING 777-200 · operated by UNITED AIRLINES INC
- Hex
- A1D8FD
- Octal
- 50354375
- Decimal
- 10,606,845
- Country
- US
- Tail
- N218UA
- Type
- B772
- Flights observed
- 117
- Distinct callsigns
- 20
- Country
- US
- Last broadcast
- 7d ago
Last known position
Country allocation
The ICAO 24-bit address A1D8FD 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 |
|---|---|---|---|
| UAL35 | United Airlines | 13 | 2026-05-06 |
| UAL34 | United Airlines | 5 | 2026-05-07 |
| UAL195 | United Airlines | 5 | 2026-04-15 |
| UAL102 | United Airlines | 5 | 2026-04-15 |
| UAL984 | United Airlines | 4 | 2026-05-19 |
| UAL942 | United Airlines | 4 | 2026-04-26 |
| UAL927 | United Airlines | 4 | 2026-04-17 |
| UAL926 | United Airlines | 4 | 2026-04-16 |
| UAL879 | - | 4 | 2026-04-14 |
| UAL673 | United Airlines | 4 | 2026-05-21 |
| UAL990 | United Airlines | 3 | 2026-05-07 |
| UAL943 | United Airlines | 3 | 2026-04-26 |
| UAL915 | United Airlines | 3 | 2026-05-08 |
| UAL59 | United Airlines | 3 | 2026-05-20 |
| UAL56 | United Airlines | 3 | 2026-05-09 |
| UAL2004 | United Airlines | 3 | 2026-04-27 |
| UAL19 | United Airlines | 3 | 2026-05-09 |
| UAL18 | United Airlines | 3 | 2026-05-10 |
| UAL969 | United Airlines | 2 | 2026-05-04 |
| UAL949 | United Airlines | 2 | 2026-04-19 |
Recent flights last 50
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-05-23 | UAL3930 | ZRH → IAD | May 23, 05:10 UTC | May 23, 05:20 UTC | 10m |
| 2026-05-22 | UAL3930 | ZRH → IAD | May 22, 15:25 UTC | May 23, 04:35 UTC | 13h 9m |
| 2026-05-21 | UAL673 | SFO → BOS | May 21, 14:45 UTC | May 22, 02:00 UTC | 11h 15m |
| 2026-05-21 | UAL672 | EWR → ATL | May 21, 01:00 UTC | May 21, 12:10 UTC | 11h 10m |
| 2026-05-20 | UAL59 | FRA → SFO | May 20, 11:55 UTC | May 20, 22:25 UTC | 10h 30m |
| 2026-05-19 | UAL58 | SFO → FRA | May 19, 21:50 UTC | May 20, 08:05 UTC | 10h 16m |
| 2026-05-19 | UAL984 | CDG → SFO | May 19, 07:39 UTC | May 19, 17:31 UTC | 9h 52m |
| 2026-05-19 | UAL984 | CDG → SFO | May 19, 07:39 UTC | May 19, 17:29 UTC | 9h 50m |
| 2026-05-19 | UAL984 | CDG → SFO | May 19, 07:25 UTC | May 19, 10:10 UTC | 2h 45m |
| 2026-05-18 | UAL57 | EWR → CDG | May 18, 21:55 UTC | May 19, 04:40 UTC | 6h 45m |
| 2026-05-18 | UAL905 | LHR → EWR | May 18, 10:05 UTC | May 18, 17:00 UTC | 6h 55m |
| 2026-05-17 | UAL880 | IAH → LHR | May 17, 21:45 UTC | May 18, 06:20 UTC | 8h 35m |
| 2026-05-16 | UAL4 | LHR → IAH | May 16, 13:01 UTC | May 16, 22:45 UTC | 9h 45m |
| 2026-05-16 | UAL5 | IAH → LHR | May 16, 01:30 UTC | May 16, 10:25 UTC | 8h 56m |
| 2026-05-15 | UAL160 | MUC → IAH | May 15, 10:30 UTC | May 15, 21:10 UTC | 10h 39m |
| 2026-05-15 | UAL160 | MUC → IAH | May 15, 10:39 UTC | May 15, 21:05 UTC | 10h 26m |
| 2026-05-14 | UAL194 | SFO → MUC | May 14, 21:25 UTC | May 15, 07:45 UTC | 10h 20m |
| 2026-05-14 | UAL984 | CDG → SFO | May 14, 07:25 UTC | May 14, 18:30 UTC | 11h 5m |
| 2026-05-13 | UAL57 | EWR → CDG | May 13, 22:15 UTC | May 14, 04:55 UTC | 6h 40m |
| 2026-05-13 | UAL2397 | EWR → PDX | May 13, 04:30 UTC | May 13, 09:05 UTC | 4h 35m |
| 2026-05-13 | UAL2397 | EWR → PDX | May 13, 04:23 UTC | May 13, 09:00 UTC | 4h 37m |
| 2026-05-12 | UAL2238 | IAH → SFO | May 12, 21:01 UTC | May 13, 01:55 UTC | 4h 55m |
| 2026-05-12 | UAL22 | DUB → EWR | May 12, 08:35 UTC | May 12, 15:20 UTC | 6h 45m |
| 2026-05-12 | UAL23 | EWR → DUB | May 12, 04:55 UTC | May 12, 05:35 UTC | 40m |
| 2026-05-11 | UAL905 | LHR → EWR | May 11, 08:50 UTC | May 11, 15:55 UTC | 7h 5m |
| 2026-05-10 | UAL14 | EWR → LHR | May 10, 23:25 UTC | May 11, 05:40 UTC | 6h 15m |
| 2026-05-10 | UAL14 | EWR → LHR | May 10, 23:30 UTC | May 11, 05:40 UTC | 6h 10m |
| 2026-05-10 | UAL18 | MXP → EWR | May 10, 08:25 UTC | May 10, 16:25 UTC | 8h 0m |
| 2026-05-09 | UAL19 | EWR → MXP | May 9, 21:48 UTC | May 10, 05:19 UTC | 7h 31m |
| 2026-05-09 | UAL19 | EWR → MXP | May 9, 21:55 UTC | May 10, 05:20 UTC | 7h 25m |
| 2026-05-09 | UAL56 | CDG → EWR | May 9, 08:05 UTC | May 9, 15:25 UTC | 7h 20m |
| 2026-05-08 | UAL915 | IAD → CDG | May 8, 22:55 UTC | May 9, 06:10 UTC | 7h 15m |
| 2026-05-08 | UAL914 | CDG → IAD | May 8, 10:39 UTC | May 8, 18:40 UTC | 8h 0m |
| 2026-05-07 | UAL990 | SFO → CDG | May 7, 22:05 UTC | May 8, 08:19 UTC | 10h 15m |
| 2026-05-07 | UAL34 | KIX → SFO | May 7, 08:30 UTC | May 7, 17:15 UTC | 8h 45m |
| 2026-05-07 | UAL34 | KIX → SFO | May 7, 04:05 UTC | May 7, 18:15 UTC | 14h 10m |
| 2026-05-06 | UAL35 | SFO → KIX | May 6, 18:15 UTC | May 7, 05:19 UTC | 11h 4m |
| 2026-05-06 | UAL35 | SFO → KIX | May 6, 18:25 UTC | May 7, 04:55 UTC | 10h 30m |
| 2026-05-05 | UAL939 | LHR → SFO | May 5, 16:30 UTC | May 6, 02:25 UTC | 9h 55m |
| 2026-05-05 | UAL930 | SFO → LHR | May 5, 03:00 UTC | May 5, 13:00 UTC | 10h 0m |
| 2026-05-04 | UAL969 | AMS → SFO | May 4, 13:16 UTC | May 4, 23:52 UTC | 10h 36m |
| 2026-05-04 | UAL969 | AMS → SFO | May 4, 13:10 UTC | May 4, 23:55 UTC | 10h 46m |
| 2026-05-03 | UAL968 | SFO → AMS | May 3, 22:34 UTC | May 4, 08:40 UTC | 10h 5m |
| 2026-05-03 | UAL34 | KIX → SFO | May 3, 08:20 UTC | May 3, 17:50 UTC | 9h 30m |
| 2026-05-02 | UAL35 | SFO → KIX | May 2, 18:15 UTC | May 3, 05:00 UTC | 10h 44m |
| 2026-05-02 | UAL35 | SFO → KIX | May 2, 18:15 UTC | May 3, 05:41 UTC | 11h 26m |
| 2026-05-01 | UAL673 | SFO → BOS | May 1, 15:20 UTC | May 1, 17:35 UTC | 2h 15m |
| 2026-05-01 | UAL673 | SFO → BOS | May 1, 15:01 UTC | May 2, 02:56 UTC | 11h 55m |
| 2026-05-01 | UAL673 | SFO → BOS | May 1, 15:01 UTC | May 2, 03:02 UTC | 12h 1m |
| 2026-05-01 | UAL672 | EWR → ATL | May 1, 01:10 UTC | May 1, 12:35 UTC | 11h 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 N218UA page for operator, model, and routing details .