sensors Mode-S transponder
A1B535
ICAO 24-bit transponder address · allocated to United States
Currently assigned to N209UA · BOEING 777-200 · operated by UNITED AIRLINES INC
- Hex
- A1B535
- Octal
- 50332465
- Decimal
- 10,597,685
- Country
- US
- Tail
- N209UA
- Type
- B772
- Flights observed
- 191
- Distinct callsigns
- 20
- Country
- US
- Last broadcast
- Jul 26, 19:25 UTC
Last known position
Country allocation
The ICAO 24-bit address A1B535 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 |
|---|---|---|---|
| UAL59 | - | 11 | 2026-07-08 |
| UAL35 | United Airlines | 10 | 2026-07-26 |
| UAL984 | - | 8 | 2026-07-18 |
| UAL34 | - | 8 | 2026-07-05 |
| UAL852 | - | 7 | 2026-07-13 |
| UAL926 | - | 6 | 2026-07-15 |
| UAL853 | - | 6 | 2026-07-12 |
| UAL819 | United Airlines | 6 | 2026-07-23 |
| UAL57 | - | 6 | 2026-07-17 |
| UAL97 | - | 5 | 2026-07-10 |
| UAL969 | United Airlines | 5 | 2026-06-08 |
| UAL968 | United Airlines | 5 | 2026-06-07 |
| UAL933 | - | 5 | 2026-07-15 |
| UAL58 | - | 5 | 2026-07-07 |
| UAL45 | - | 5 | 2026-07-14 |
| UAL195 | United Airlines | 5 | 2026-07-25 |
| UAL160 | United Airlines | 5 | 2026-07-22 |
| UAL927 | - | 4 | 2026-07-11 |
| UAL803 | United Airlines | 4 | 2026-06-25 |
| UAL44 | - | 4 | 2026-07-13 |
Recent flights last 50
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-07-26 | UAL35 | SFO → KIX | Jul 26, 18:55 UTC | Jul 26, 19:25 UTC | 30m |
| 2026-07-25 | UAL195 | MUC → SFO | Jul 25, 10:05 UTC | Jul 25, 21:15 UTC | 11h 10m |
| 2026-07-24 | UAL102 | IAH → MUC | Jul 24, 22:20 UTC | Jul 25, 07:15 UTC | 8h 55m |
| 2026-07-24 | UAL102 | IAH → MUC | Jul 24, 22:22 UTC | Jul 25, 07:45 UTC | 9h 23m |
| 2026-07-24 | UAL818 | EZE → IAH | Jul 24, 00:10 UTC | Jul 24, 09:50 UTC | 9h 40m |
| 2026-07-23 | UAL819 | IAH → EZE | Jul 23, 02:25 UTC | Jul 23, 11:50 UTC | 9h 25m |
| 2026-07-22 | UAL160 | MUC → IAH | Jul 22, 11:10 UTC | Jul 22, 21:15 UTC | 10h 5m |
| 2026-07-21 | UAL160 | MUC → IAH | Jul 21, 23:20 UTC | Jul 22, 21:15 UTC | 21h 55m |
| 2026-07-21 | UAL160 | MUC → IAH | Jul 21, 21:25 UTC | Jul 22, 21:15 UTC | 23h 50m |
| 2026-07-18 | UAL984 | - | Jul 18, 09:05 UTC | Jul 18, 10:45 UTC | 1h 40m |
| 2026-07-18 | UAL984 | CDG → SFO | Jul 18, 08:57 UTC | Jul 18, 19:34 UTC | 10h 37m |
| 2026-07-18 | UAL984 | CDG → SFO | Jul 18, 08:57 UTC | Jul 18, 19:40 UTC | 10h 43m |
| 2026-07-17 | UAL57 | EWR → CDG | Jul 17, 23:33 UTC | Jul 18, 06:21 UTC | 6h 48m |
| 2026-07-17 | UAL57 | - | Jul 17, 23:45 UTC | Jul 18, 01:20 UTC | 1h 35m |
| 2026-07-17 | UAL56 | CDG → EWR | Jul 17, 08:20 UTC | Jul 17, 15:49 UTC | 7h 30m |
| 2026-07-17 | UAL56 | CDG → EWR | Jul 17, 08:22 UTC | Jul 17, 15:48 UTC | 7h 26m |
| 2026-07-16 | UAL915 | IAD → CDG | Jul 16, 22:31 UTC | Jul 17, 05:41 UTC | 7h 10m |
| 2026-07-16 | UAL915 | - | Jul 16, 22:45 UTC | Jul 17, 05:15 UTC | 6h 30m |
| 2026-07-15 | UAL933 | FRA → IAD | Jul 15, 15:55 UTC | Jul 16, 00:00 UTC | 8h 5m |
| 2026-07-15 | UAL933 | FRA → IAD | Jul 15, 15:51 UTC | Jul 15, 23:59 UTC | 8h 8m |
| 2026-07-15 | UAL926 | SFO → FRA | Jul 15, 02:49 UTC | Jul 15, 13:44 UTC | 10h 55m |
| 2026-07-15 | UAL926 | SFO → FRA | Jul 15, 03:25 UTC | Jul 15, 13:40 UTC | 10h 15m |
| 2026-07-14 | UAL45 | ZRH → SFO | Jul 14, 12:27 UTC | Jul 14, 23:56 UTC | 11h 29m |
| 2026-07-14 | UAL45 | - | Jul 14, 12:35 UTC | Jul 14, 14:40 UTC | 2h 5m |
| 2026-07-13 | UAL44 | SFO → ZRH | Jul 13, 21:48 UTC | Jul 14, 08:18 UTC | 10h 30m |
| 2026-07-13 | UAL44 | SFO → ZRH | Jul 13, 22:05 UTC | Jul 14, 08:15 UTC | 10h 10m |
| 2026-07-13 | UAL852 | - | Jul 13, 07:05 UTC | Jul 13, 09:15 UTC | 2h 10m |
| 2026-07-13 | UAL852 | TPE → SFO | Jul 13, 06:51 UTC | Jul 13, 18:39 UTC | 11h 48m |
| 2026-07-13 | UAL852 | TPE → SFO | Jul 13, 06:51 UTC | Jul 13, 18:43 UTC | 11h 52m |
| 2026-07-12 | UAL853 | SFO → TPE | Jul 12, 07:41 UTC | Jul 12, 19:43 UTC | 12h 2m |
| 2026-07-12 | UAL853 | - | Jul 12, 07:35 UTC | Jul 12, 08:01 UTC | 25m |
| 2026-07-11 | UAL927 | - | Jul 11, 16:00 UTC | Jul 12, 03:15 UTC | 11h 15m |
| 2026-07-11 | UAL927 | FRA → SFO | Jul 11, 15:51 UTC | Jul 12, 03:24 UTC | 11h 33m |
| 2026-07-11 | UAL926 | SFO → FRA | Jul 11, 02:44 UTC | Jul 11, 12:36 UTC | 9h 52m |
| 2026-07-11 | UAL926 | - | Jul 11, 02:30 UTC | Jul 11, 11:15 UTC | 8h 45m |
| 2026-07-10 | UAL97 | BNE → SFO | Jul 10, 07:18 UTC | Jul 10, 19:38 UTC | 12h 20m |
| 2026-07-10 | UAL97 | BNE → SFO | Jul 10, 07:18 UTC | Jul 10, 19:37 UTC | 12h 19m |
| 2026-07-10 | UAL97 | - | Jul 10, 07:20 UTC | Jul 10, 07:55 UTC | 35m |
| 2026-07-09 | UAL96 | SFO → BNE | Jul 9, 15:35 UTC | Jul 10, 05:15 UTC | 13h 40m |
| 2026-07-08 | UAL59 | - | Jul 8, 11:20 UTC | Jul 8, 13:15 UTC | 1h 55m |
| 2026-07-08 | UAL59 | FRA → SFO | Jul 8, 11:24 UTC | Jul 8, 22:19 UTC | 10h 55m |
| 2026-07-08 | UAL59 | FRA → SFO | Jul 8, 11:24 UTC | Jul 8, 22:19 UTC | 10h 55m |
| 2026-07-07 | UAL58 | SFO → FRA | Jul 7, 21:45 UTC | Jul 8, 07:50 UTC | 10h 5m |
| 2026-07-06 | UAL59 | - | Jul 6, 11:25 UTC | Jul 6, 13:20 UTC | 1h 55m |
| 2026-07-06 | UAL59 | FRA → SFO | Jul 6, 11:29 UTC | Jul 6, 22:19 UTC | 10h 50m |
| 2026-07-05 | UAL58 | SFO → FRA | Jul 5, 22:10 UTC | Jul 6, 08:15 UTC | 10h 5m |
| 2026-07-05 | UAL34 | - | Jul 5, 08:10 UTC | Jul 5, 17:50 UTC | 9h 40m |
| 2026-07-04 | UAL35 | SFO → KIX | Jul 4, 18:35 UTC | Jul 5, 05:15 UTC | 10h 40m |
| 2026-07-03 | UAL889 | PEK → SFO | Jul 3, 21:00 UTC | Jul 4, 07:15 UTC | 10h 15m |
| 2026-07-03 | UAL889 | PEK → SFO | Jul 3, 19:41 UTC | Jul 4, 07:17 UTC | 11h 36m |
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 N209UA page for operator, model, and routing details .