sensors Mode-S transponder
3543C3
ICAO 24-bit transponder address · allocated to Spain
Currently assigned to HD.21-18 · AEROSPATIALE AS-332 Super Puma
- Hex
- 3543C3
- Octal
- 15241703
- Decimal
- 3,490,755
- Country
- ES
- Tail
- HD.21-18
- Type
- AS32
- Flights observed
- 21
- Distinct callsigns
- 10
- Country
- ES
- Last broadcast
- 11h ago
Last known position
Country allocation
The ICAO 24-bit address 3543C3 falls within the block assigned to Spain (ES) by ICAO Annex 10, Volume III. Every aircraft registered in Spain 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 10 distinct
Recent flights last 21
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-07-04 | AME4609 | - | Jul 4, 08:15 UTC | Jul 4, 10:35 UTC | 2h 20m |
| 2026-07-02 | COTOS13A | - | Jul 2, 20:15 UTC | Jul 2, 21:55 UTC | 1h 40m |
| 2026-06-12 | COTOS12 | - | Jun 12, 15:15 UTC | Jun 12, 15:50 UTC | 35m |
| 2026-06-10 | COTOS14A | - | Jun 10, 19:05 UTC | Jun 10, 20:35 UTC | 1h 30m |
| 2026-06-09 | COTOS15A | - | Jun 9, 21:20 UTC | Jun 9, 21:30 UTC | 10m |
| 2026-06-08 | COTOS11 | - | Jun 8, 13:20 UTC | Jun 8, 13:50 UTC | 30m |
| 2026-06-03 | COTOS14 | - | Jun 3, 17:20 UTC | Jun 3, 17:45 UTC | 25m |
| 2026-06-03 | COTOS13 | - | Jun 3, 15:45 UTC | Jun 3, 16:10 UTC | 25m |
| 2026-06-01 | COTOS140 | - | Jun 1, 13:05 UTC | Jun 1, 13:25 UTC | 20m |
| 2026-06-01 | COTOS13 | - | Jun 1, 10:50 UTC | Jun 1, 11:10 UTC | 20m |
| 2026-06-01 | COTOS12 | - | Jun 1, 08:20 UTC | Jun 1, 09:15 UTC | 55m |
| 2026-05-24 | COTOS11 | - | May 24, 12:05 UTC | May 24, 12:15 UTC | 10m |
| 2026-05-21 | COTOS12 | - | May 21, 12:35 UTC | May 21, 13:05 UTC | 30m |
| 2026-05-21 | COTOS12 | - | May 21, 11:05 UTC | May 21, 11:30 UTC | 25m |
| 2026-05-20 | COTOS14 | - | May 20, 17:25 UTC | May 20, 17:40 UTC | 15m |
| 2026-05-20 | COTOS13 | - | May 20, 15:20 UTC | May 20, 15:40 UTC | 20m |
| 2026-05-20 | COTOS11 | - | May 20, 09:00 UTC | May 20, 09:20 UTC | 20m |
| 2026-05-19 | COTOS11 | - | May 19, 10:50 UTC | May 19, 11:00 UTC | 10m |
| 2026-05-19 | COTOS11 | - | May 19, 08:40 UTC | May 19, 08:50 UTC | 10m |
| 2026-05-18 | COTOS12 | - | May 18, 13:00 UTC | May 18, 13:40 UTC | 40m |
| 2026-05-12 | COTOS15 | - | May 12, 19:55 UTC | May 12, 20:20 UTC | 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 HD.21-18 page for operator, model, and routing details .