sensors Mode-S transponder
402991
ICAO 24-bit transponder address · allocated to United Kingdom
Currently assigned to G-GYAV · CESSNA 172 Skyhawk
- Hex
- 402991
- Octal
- 20024621
- Decimal
- 4,204,945
- Country
- GB
- Tail
- G-GYAV
- Type
- C172
- Flights observed
- 24
- Distinct callsigns
- 1
- Country
- GB
- Last broadcast
- 21h ago
Current position
Country allocation
The ICAO 24-bit address 402991 falls within the block assigned to United Kingdom (GB) by ICAO Annex 10, Volume III. Every aircraft registered in United Kingdom 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 1 distinct
| Callsign | Airline | Flights | Last seen |
|---|---|---|---|
| GGYAV | - | 24 | 2026-05-29 |
Recent flights last 24
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-05-29 | GGYAV | - | May 29, 14:40 UTC | May 29, 15:20 UTC | 40m |
| 2026-05-29 | GGYAV | - | May 29, 12:35 UTC | May 29, 13:15 UTC | 40m |
| 2026-05-28 | GGYAV | - | May 28, 15:20 UTC | May 28, 15:55 UTC | 35m |
| 2026-05-28 | GGYAV | - | May 28, 11:35 UTC | May 28, 12:20 UTC | 45m |
| 2026-05-27 | GGYAV | - | May 27, 13:30 UTC | May 27, 14:15 UTC | 45m |
| 2026-05-25 | GGYAV | - | May 25, 12:05 UTC | May 25, 12:45 UTC | 40m |
| 2026-05-23 | GGYAV | - | May 23, 12:35 UTC | May 23, 14:05 UTC | 1h 30m |
| 2026-05-23 | GGYAV | - | May 23, 09:15 UTC | May 23, 11:00 UTC | 1h 45m |
| 2026-05-22 | GGYAV | - | May 22, 16:40 UTC | May 22, 17:30 UTC | 50m |
| 2026-04-25 | GGYAV | - | Apr 25, 13:40 UTC | Apr 25, 14:15 UTC | 35m |
| 2026-04-25 | GGYAV | - | Apr 25, 11:05 UTC | Apr 25, 11:25 UTC | 20m |
| 2026-04-23 | GGYAV | - | Apr 23, 15:20 UTC | Apr 23, 15:30 UTC | 10m |
| 2026-04-23 | GGYAV | - | Apr 23, 13:10 UTC | Apr 23, 13:45 UTC | 35m |
| 2026-04-22 | GGYAV | - | Apr 22, 14:50 UTC | Apr 22, 15:25 UTC | 35m |
| 2026-04-22 | GGYAV | - | Apr 22, 12:45 UTC | Apr 22, 13:25 UTC | 40m |
| 2026-04-21 | GGYAV | - | Apr 21, 13:10 UTC | Apr 21, 13:35 UTC | 25m |
| 2026-04-21 | GGYAV | - | Apr 21, 11:40 UTC | Apr 21, 11:55 UTC | 15m |
| 2026-04-21 | GGYAV | - | Apr 21, 10:15 UTC | Apr 21, 11:05 UTC | 50m |
| 2026-04-19 | GGYAV | - | Apr 19, 10:30 UTC | Apr 19, 11:15 UTC | 45m |
| 2026-04-19 | GGYAV | - | Apr 19, 08:45 UTC | Apr 19, 09:15 UTC | 30m |
| 2026-04-18 | GGYAV | - | Apr 18, 14:30 UTC | Apr 18, 14:50 UTC | 20m |
| 2026-04-18 | GGYAV | - | Apr 18, 12:15 UTC | Apr 18, 12:50 UTC | 35m |
| 2026-04-13 | GGYAV | - | Apr 13, 13:25 UTC | Apr 13, 13:45 UTC | 20m |
| 2026-04-13 | GGYAV | - | Apr 13, 10:50 UTC | Apr 13, 11:50 UTC | 1h 0m |
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 G-GYAV page for operator, model, and routing details .