sensors Mode-S transponder
4D21DD
ICAO 24-bit transponder address · allocated to Malta
Currently assigned to 9H-LKF · BOMBARDIER Regional Jet CRJ-1000
- Hex
- 4D21DD
- Octal
- 23220735
- Decimal
- 5,054,941
- Country
- MT
- Tail
- 9H-LKF
- Type
- CRJX
- Flights observed
- 10
- Distinct callsigns
- 10
- Country
- MT
- Last broadcast
- Jul 26, 19:20 UTC
Current position
Country allocation
The ICAO 24-bit address 4D21DD falls within the block assigned to Malta (MT) by ICAO Annex 10, Volume III. Every aircraft registered in Malta 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 10
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-07-26 | WMT1ZY | - | Jul 26, 17:25 UTC | Jul 26, 19:20 UTC | 1h 55m |
| 2026-07-26 | WMT39FA | - | Jul 26, 14:00 UTC | Jul 26, 15:30 UTC | 1h 30m |
| 2026-07-26 | WMT8917 | FCO → VLC | Jul 26, 11:00 UTC | Jul 26, 12:50 UTC | 1h 50m |
| 2026-07-26 | WMT7474 | - | Jul 26, 08:30 UTC | Jul 26, 09:40 UTC | 1h 10m |
| 2026-07-26 | WMT2977 | - | Jul 26, 05:45 UTC | Jul 26, 07:10 UTC | 1h 26m |
| 2026-07-25 | WMT1488 | - | Jul 25, 23:50 UTC | Jul 26, 01:05 UTC | 1h 15m |
| 2026-07-25 | WMT8077 | - | Jul 25, 19:20 UTC | Jul 25, 20:55 UTC | 1h 35m |
| 2026-07-25 | WMT8FK | - | Jul 25, 16:35 UTC | Jul 25, 18:05 UTC | 1h 30m |
| 2026-07-25 | WMT1EF | - | Jul 25, 13:55 UTC | Jul 25, 15:25 UTC | 1h 30m |
| 2026-07-25 | WMT801 | CRA → OTP | Jul 25, 10:55 UTC | Jul 25, 12:25 UTC | 1h 30m |
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 9H-LKF page for operator, model, and routing details .