sensors Mode-S transponder
AA9321
ICAO 24-bit transponder address · allocated to United States
Currently assigned to N78017 · BOEING 777-200 · operated by UNITED AIRLINES INC
- Hex
- AA9321
- Octal
- 52511441
- Decimal
- 11,178,785
- Country
- US
- Tail
- N78017
- Type
- B772
- Flights observed
- 122
- Distinct callsigns
- 20
- Country
- US
- Last broadcast
- 2h ago
Last known position
Country allocation
The ICAO 24-bit address AA9321 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 |
|---|---|---|---|
| UAL888 | United Airlines | 12 | 2026-05-28 |
| UAL889 | United Airlines | 8 | 2026-05-29 |
| UAL96 | United Airlines | 4 | 2026-05-14 |
| UAL939 | United Airlines | 4 | 2026-04-27 |
| UAL932 | United Airlines | 4 | 2026-04-15 |
| UAL927 | United Airlines | 4 | 2026-05-18 |
| UAL925 | United Airlines | 4 | 2026-04-14 |
| UAL507 | United Airlines | 4 | 2026-05-30 |
| UAL46 | - | 4 | 2026-04-13 |
| UAL97 | United Airlines | 3 | 2026-05-15 |
| UAL943 | United Airlines | 3 | 2026-04-16 |
| UAL942 | United Airlines | 3 | 2026-04-16 |
| UAL875 | United Airlines | 3 | 2026-05-19 |
| UAL852 | United Airlines | 3 | 2026-05-11 |
| UAL803 | United Airlines | 3 | 2026-04-18 |
| UAL70 | United Airlines | 3 | 2026-04-21 |
| UAL130 | United Airlines | 3 | 2026-05-20 |
| UAL948 | United Airlines | 2 | 2026-05-16 |
| UAL933 | United Airlines | 2 | 2026-04-15 |
| UAL930 | United Airlines | 2 | 2026-04-27 |
Recent flights last 50
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-05-30 | UAL507 | DEN → LGA | May 30, 00:20 UTC | May 30, 03:05 UTC | 2h 45m |
| 2026-05-29 | UAL889 | PEK → SFO | May 29, 10:50 UTC | May 29, 21:00 UTC | 10h 10m |
| 2026-05-29 | UAL889 | PEK → SFO | May 29, 09:51 UTC | May 29, 20:59 UTC | 11h 8m |
| 2026-05-28 | UAL888 | SFO → PEK | May 28, 18:00 UTC | May 29, 06:25 UTC | 12h 25m |
| 2026-05-28 | UAL916 | AKL → SFO | May 28, 02:00 UTC | May 28, 13:30 UTC | 11h 30m |
| 2026-05-27 | UAL917 | SFO → AKL | May 27, 06:34 UTC | May 27, 19:15 UTC | 12h 40m |
| 2026-05-26 | UAL506 | MSN → DEN | May 26, 13:54 UTC | May 27, 01:59 UTC | 12h 5m |
| 2026-05-26 | UAL507 | DEN → LGA | May 26, 00:29 UTC | May 26, 11:44 UTC | 11h 15m |
| 2026-05-25 | UAL195 | MUC → SFO | May 25, 10:15 UTC | May 25, 12:05 UTC | 1h 50m |
| 2026-05-25 | UAL195 | MUC → SFO | May 25, 10:15 UTC | May 25, 21:20 UTC | 11h 5m |
| 2026-05-24 | UAL102 | IAH → MUC | May 24, 23:00 UTC | May 25, 07:30 UTC | 8h 30m |
| 2026-05-24 | UAL102 | IAH → MUC | May 24, 22:27 UTC | May 25, 07:31 UTC | 9h 4m |
| 2026-05-24 | UAL879 | LHR → IAH | May 24, 09:25 UTC | May 24, 19:20 UTC | 9h 55m |
| 2026-05-23 | UAL918 | IAD → LHR | May 23, 22:56 UTC | May 24, 05:28 UTC | 6h 32m |
| 2026-05-23 | UAL918 | IAD → LHR | May 23, 22:45 UTC | May 24, 05:35 UTC | 6h 50m |
| 2026-05-23 | UAL804 | HND → IAD | May 23, 07:10 UTC | May 23, 19:23 UTC | 12h 13m |
| 2026-05-23 | UAL804 | HND → IAD | May 23, 07:05 UTC | May 23, 19:20 UTC | 12h 15m |
| 2026-05-22 | UAL131 | EWR → HND | May 22, 14:53 UTC | May 23, 04:28 UTC | 13h 35m |
| 2026-05-22 | UAL131 | EWR → HND | May 22, 14:45 UTC | May 22, 23:05 UTC | 8h 20m |
| 2026-05-22 | UAL148 | GRU → EWR | May 22, 00:20 UTC | May 22, 01:05 UTC | 45m |
| 2026-05-22 | UAL148 | GRU → EWR | May 22, 00:21 UTC | May 22, 09:28 UTC | 9h 7m |
| 2026-05-21 | UAL149 | EWR → GRU | May 21, 03:30 UTC | May 21, 05:25 UTC | 1h 55m |
| 2026-05-21 | UAL149 | EWR → GRU | May 21, 02:01 UTC | May 21, 12:22 UTC | 10h 21m |
| 2026-05-20 | UAL130 | HND → EWR | May 20, 09:20 UTC | May 20, 21:20 UTC | 12h 0m |
| 2026-05-19 | UAL875 | SFO → HND | May 19, 18:55 UTC | May 20, 05:25 UTC | 10h 31m |
| 2026-05-18 | UAL927 | FRA → SFO | May 18, 15:50 UTC | May 18, 17:35 UTC | 1h 45m |
| 2026-05-18 | UAL927 | FRA → SFO | May 18, 15:51 UTC | May 19, 02:21 UTC | 10h 30m |
| 2026-05-18 | UAL927 | FRA → SFO | May 18, 15:51 UTC | May 19, 02:24 UTC | 10h 33m |
| 2026-05-18 | UAL926 | SFO → FRA | May 18, 02:25 UTC | May 18, 12:45 UTC | 10h 20m |
| 2026-05-17 | UAL949 | LHR → SFO | May 17, 12:40 UTC | May 17, 22:35 UTC | 9h 55m |
| 2026-05-16 | UAL948 | SFO → LHR | May 16, 23:59 UTC | May 17, 09:32 UTC | 9h 33m |
| 2026-05-16 | UAL948 | SFO → LHR | May 16, 23:55 UTC | May 17, 09:35 UTC | 9h 40m |
| 2026-05-16 | UAL889 | PEK → SFO | May 16, 04:15 UTC | May 16, 20:45 UTC | 16h 30m |
| 2026-05-15 | UAL888 | SFO → PEK | May 15, 22:20 UTC | May 16, 20:45 UTC | 22h 25m |
| 2026-05-15 | UAL888 | SFO → PEK | May 15, 20:20 UTC | May 16, 20:15 UTC | 23h 56m |
| 2026-05-15 | UAL888 | SFO → PEK | May 15, 18:20 UTC | May 16, 12:55 UTC | 18h 36m |
| 2026-05-15 | UAL888 | SFO → PEK | May 15, 18:10 UTC | May 16, 12:55 UTC | 18h 46m |
| 2026-05-15 | UAL97 | BNE → SFO | May 15, 01:05 UTC | May 15, 13:30 UTC | 12h 25m |
| 2026-05-14 | UAL96 | SFO → BNE | May 14, 06:50 UTC | May 14, 20:23 UTC | 13h 33m |
| 2026-05-14 | UAL96 | SFO → BNE | May 14, 06:55 UTC | May 14, 11:40 UTC | 4h 45m |
| 2026-05-13 | UAL673 | SFO → BOS | May 13, 14:40 UTC | May 14, 02:45 UTC | 12h 5m |
| 2026-05-13 | UAL673 | SFO → BOS | May 13, 14:31 UTC | May 14, 02:38 UTC | 12h 7m |
| 2026-05-13 | UAL672 | EWR → ATL | May 13, 01:00 UTC | May 13, 11:50 UTC | 10h 50m |
| 2026-05-11 | UAL852 | TPE → SAN | May 11, 07:55 UTC | May 11, 08:15 UTC | 20m |
| 2026-05-11 | UAL852 | TPE → SAN | May 11, 06:51 UTC | May 11, 17:33 UTC | 10h 42m |
| 2026-05-11 | UAL852 | TPE → SAN | May 11, 06:35 UTC | May 11, 06:50 UTC | 15m |
| 2026-05-10 | UAL853 | SFO → TPE | May 10, 06:50 UTC | May 10, 19:54 UTC | 13h 5m |
| 2026-05-09 | UAL927 | FRA → SFO | May 9, 16:00 UTC | May 10, 02:50 UTC | 10h 50m |
| 2026-05-09 | UAL926 | SFO → FRA | May 9, 02:30 UTC | May 9, 12:45 UTC | 10h 15m |
| 2026-05-08 | UAL889 | PEK → SFO | May 8, 11:56 UTC | May 8, 22:05 UTC | 10h 9m |
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 N78017 page for operator, model, and routing details .