sensors Mode-S transponder
43BC99
ICAO 24-bit transponder address · allocated to United Kingdom
- Hex
- 43BC99
- Octal
- 20736231
- Decimal
- 4,439,193
- Country
- GB
- Flights observed
- 25
- Distinct callsigns
- 1
- Country
- GB
- Last broadcast
- 5d ago
Current position
Country allocation
The ICAO 24-bit address 43BC99 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 |
|---|---|---|---|
| TOPCLFE3 | - | 25 | 2026-07-12 |
Recent flights last 25
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-07-12 | TOPCLFE3 | - | Jul 12, 12:45 UTC | Jul 12, 15:35 UTC | 2h 50m |
| 2026-07-12 | TOPCLFE3 | - | Jul 12, 09:50 UTC | Jul 12, 11:35 UTC | 1h 45m |
| 2026-07-05 | TOPCLFE3 | - | Jul 5, 11:10 UTC | Jul 5, 11:50 UTC | 40m |
| 2026-06-27 | TOPCLFE3 | - | Jun 27, 10:19 UTC | Jun 27, 15:49 UTC | 5h 30m |
| 2026-06-21 | TOPCLFE3 | - | Jun 21, 09:44 UTC | Jun 21, 15:44 UTC | 6h 0m |
| 2026-06-21 | TOPCLFE3 | - | Jun 21, 07:45 UTC | Jun 21, 09:10 UTC | 1h 25m |
| 2026-06-20 | TOPCLFE3 | - | Jun 20, 08:39 UTC | Jun 20, 15:04 UTC | 6h 25m |
| 2026-06-14 | TOPCLFE3 | - | Jun 14, 09:55 UTC | Jun 14, 11:10 UTC | 1h 15m |
| 2026-06-14 | TOPCLFE3 | - | Jun 14, 09:05 UTC | Jun 14, 09:15 UTC | 10m |
| 2026-06-13 | TOPCLFE3 | - | Jun 13, 10:20 UTC | Jun 13, 11:40 UTC | 1h 20m |
| 2026-06-07 | TOPCLFE3 | - | Jun 7, 13:20 UTC | Jun 7, 13:50 UTC | 30m |
| 2026-06-07 | TOPCLFE3 | - | Jun 7, 10:10 UTC | Jun 7, 11:15 UTC | 1h 5m |
| 2026-05-25 | TOPCLFE3 | - | May 25, 08:45 UTC | May 25, 14:45 UTC | 6h 0m |
| 2026-05-23 | TOPCLFE3 | - | May 23, 08:50 UTC | May 23, 09:00 UTC | 10m |
| 2026-05-17 | TOPCLFE3 | - | May 17, 09:30 UTC | May 17, 14:55 UTC | 5h 25m |
| 2026-05-16 | TOPCLFE3 | - | May 16, 07:35 UTC | May 16, 15:25 UTC | 7h 50m |
| 2026-05-10 | TOPCLFE3 | - | May 10, 13:10 UTC | May 10, 14:49 UTC | 1h 40m |
| 2026-05-10 | TOPCLFE3 | - | May 10, 10:45 UTC | May 10, 11:50 UTC | 1h 5m |
| 2026-05-10 | TOPCLFE3 | - | May 10, 09:24 UTC | May 10, 10:15 UTC | 50m |
| 2026-05-04 | TOPCLFE3 | - | May 4, 09:25 UTC | May 4, 15:00 UTC | 5h 35m |
| 2026-04-26 | TOPCLFE3 | - | Apr 26, 12:25 UTC | Apr 26, 14:50 UTC | 2h 25m |
| 2026-04-25 | TOPCLFE3 | - | Apr 25, 09:35 UTC | Apr 25, 15:45 UTC | 6h 10m |
| 2026-04-19 | TOPCLFE3 | - | Apr 19, 12:10 UTC | Apr 19, 14:10 UTC | 2h 0m |
| 2026-04-19 | TOPCLFE3 | - | Apr 19, 09:15 UTC | Apr 19, 11:25 UTC | 2h 10m |
| 2026-04-18 | TOPCLFE3 | - | Apr 18, 09:00 UTC | Apr 18, 14:25 UTC | 5h 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.