sensors Mode-S transponder
4D2421
ICAO 24-bit transponder address
Currently assigned to 9H-WAL · AIRBUS A-321neo
- Hex
- 4D2421
- Octal
- 23222041
- Decimal
- 5,055,521
- Tail
- 9H-WAL
- Type
- A21N
Broadcasting now · callsign WMT228 · 37,000 ft
- Flights observed
- 258
- Distinct callsigns
- 20
- Country
- -
- Last broadcast
- 1d ago
Current position
Callsign history 20 distinct
| Callsign | Airline | Flights | Last seen |
|---|---|---|---|
| WMT5UD | - | 4 | 2026-07-04 |
| WMT3051 | - | 4 | 2026-07-26 |
| WMT1TG | - | 4 | 2026-07-04 |
| WZZ5MD | Wizz Air | 3 | 2026-06-24 |
| WZZ4SM | - | 3 | 2026-06-24 |
| WMT9DJ | - | 3 | 2026-07-12 |
| WMT7UV | Wizz Air Malta | 3 | 2026-07-26 |
| WMT7QH | - | 3 | 2026-07-26 |
| WMT7M | - | 3 | 2026-07-20 |
| WMT7CF | Wizz Air Malta | 3 | 2026-07-25 |
| WMT7388 | - | 3 | 2026-07-20 |
| WMT727 | - | 3 | 2026-07-14 |
| WMT6KA | Wizz Air Malta | 3 | 2026-07-25 |
| WMT5353 | - | 3 | 2026-07-14 |
| WMT311M | - | 3 | 2026-07-12 |
| WMT2EK | - | 3 | 2026-07-12 |
| WMT2DN | - | 3 | 2026-07-26 |
| WMT228 | - | 3 | 2026-07-12 |
| WZZ9389 | - | 2 | 2026-06-18 |
| WZZ8594 | - | 2 | 2026-06-15 |
Recent flights last 50
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-07-26 | WMT747 | MLA → OTP | Jul 26, 19:40 UTC | Jul 26, 21:30 UTC | 1h 50m |
| 2026-07-26 | WMT599 | - | Jul 26, 16:40 UTC | Jul 26, 18:40 UTC | 2h 0m |
| 2026-07-26 | WMT2DN | - | Jul 26, 14:05 UTC | Jul 26, 15:20 UTC | 1h 15m |
| 2026-07-26 | WMT3051 | - | Jul 26, 11:50 UTC | Jul 26, 13:10 UTC | 1h 20m |
| 2026-07-26 | WMT7QH | - | Jul 26, 07:40 UTC | Jul 26, 09:55 UTC | 2h 15m |
| 2026-07-26 | WMT7UV | OTP → EIN | Jul 26, 04:10 UTC | Jul 26, 06:40 UTC | 2h 31m |
| 2026-07-25 | WMT6KA | NCE → OTP | Jul 25, 21:15 UTC | Jul 25, 23:05 UTC | 1h 50m |
| 2026-07-25 | WMT7CF | OTP → NCE | Jul 25, 17:50 UTC | Jul 25, 20:10 UTC | 2h 20m |
| 2026-07-25 | WMT551 | LTN → OTP | Jul 25, 13:30 UTC | Jul 25, 16:20 UTC | 2h 50m |
| 2026-07-25 | WMT8585 | - | Jul 25, 09:00 UTC | Jul 25, 12:00 UTC | 3h 0m |
| 2026-07-25 | WMT7WQ | BER → OTP | Jul 25, 05:55 UTC | Jul 25, 07:35 UTC | 1h 40m |
| 2026-07-25 | WMT2GJ | OTP → BER | Jul 25, 02:50 UTC | Jul 25, 04:45 UTC | 1h 55m |
| 2026-07-24 | WMT72ZH | BDS → OTP | Jul 24, 21:25 UTC | Jul 24, 22:35 UTC | 1h 10m |
| 2026-07-24 | WMT3969 | OTP → BDS | Jul 24, 19:20 UTC | Jul 24, 20:25 UTC | 1h 5m |
| 2026-07-24 | WMT367 | HAM → SBZ | Jul 24, 16:05 UTC | Jul 24, 18:15 UTC | 2h 10m |
| 2026-07-24 | WMT4470 | - | Jul 24, 12:15 UTC | Jul 24, 14:40 UTC | 2h 25m |
| 2026-07-24 | WMT7QH | - | Jul 24, 07:30 UTC | Jul 24, 09:40 UTC | 2h 10m |
| 2026-07-24 | WMT7UV | OTP → EIN | Jul 24, 04:05 UTC | Jul 24, 06:35 UTC | 2h 30m |
| 2026-07-23 | WMT4GW | MAD → OTP | Jul 23, 18:05 UTC | Jul 23, 21:20 UTC | 3h 15m |
| 2026-07-23 | WMT5ST | OTP → CGN | Jul 23, 12:30 UTC | Jul 23, 16:15 UTC | 3h 45m |
| 2026-07-23 | WMT7NW | - | Jul 23, 08:05 UTC | Jul 23, 10:45 UTC | 2h 40m |
| 2026-07-23 | WMT6KX | - | Jul 23, 03:30 UTC | Jul 23, 06:05 UTC | 2h 35m |
| 2026-07-22 | WMT4942 | - | Jul 22, 21:00 UTC | Jul 22, 23:15 UTC | 2h 15m |
| 2026-07-22 | WMT272 | - | Jul 22, 17:20 UTC | Jul 22, 20:00 UTC | 2h 40m |
| 2026-07-22 | WMT4E | - | Jul 22, 15:10 UTC | Jul 22, 16:10 UTC | 1h 0m |
| 2026-07-22 | WMT2JK | - | Jul 22, 12:20 UTC | Jul 22, 13:25 UTC | 1h 5m |
| 2026-07-22 | WMT6KX | - | Jul 22, 03:30 UTC | Jul 22, 10:25 UTC | 6h 55m |
| 2026-07-21 | WMT89JC | - | Jul 21, 20:45 UTC | Jul 21, 23:00 UTC | 2h 15m |
| 2026-07-21 | WMT7TW | - | Jul 21, 17:30 UTC | Jul 21, 19:40 UTC | 2h 10m |
| 2026-07-21 | WMT8GC | - | Jul 21, 14:30 UTC | Jul 21, 16:20 UTC | 1h 50m |
| 2026-07-21 | WMT1CF | - | Jul 21, 11:15 UTC | Jul 21, 13:20 UTC | 2h 5m |
| 2026-07-21 | WMT17GF | - | Jul 21, 06:50 UTC | Jul 21, 08:35 UTC | 1h 45m |
| 2026-07-21 | WMT2SX | - | Jul 21, 03:15 UTC | Jul 21, 05:25 UTC | 2h 10m |
| 2026-07-20 | WMT7M | - | Jul 20, 18:45 UTC | Jul 20, 21:25 UTC | 2h 40m |
| 2026-07-20 | WMT7388 | - | Jul 20, 13:55 UTC | Jul 20, 17:15 UTC | 3h 20m |
| 2026-07-20 | WMT193 | - | Jul 20, 11:20 UTC | Jul 20, 12:30 UTC | 1h 10m |
| 2026-07-20 | WMT1800 | - | Jul 20, 08:55 UTC | Jul 20, 10:30 UTC | 1h 35m |
| 2026-07-20 | WMT6UQ | CLJ → VLC | Jul 20, 06:30 UTC | Jul 20, 08:00 UTC | 1h 30m |
| 2026-07-20 | WMT102 | - | Jul 20, 03:45 UTC | Jul 20, 05:30 UTC | 1h 45m |
| 2026-07-19 | WMT905 | - | Jul 19, 19:25 UTC | Jul 19, 22:10 UTC | 2h 45m |
| 2026-07-19 | WMT9CR | - | Jul 19, 14:45 UTC | Jul 19, 18:15 UTC | 3h 30m |
| 2026-07-19 | WMT7BV | - | Jul 19, 11:45 UTC | Jul 19, 13:05 UTC | 1h 20m |
| 2026-07-19 | WMT7340 | - | Jul 19, 09:10 UTC | Jul 19, 10:50 UTC | 1h 40m |
| 2026-07-19 | WMT3662 | - | Jul 19, 06:45 UTC | Jul 19, 08:05 UTC | 1h 20m |
| 2026-07-19 | WMT917 | - | Jul 19, 03:50 UTC | Jul 19, 05:35 UTC | 1h 45m |
| 2026-07-17 | WMT7M | - | Jul 17, 19:15 UTC | Jul 17, 21:55 UTC | 2h 40m |
| 2026-07-17 | WMT7388 | - | Jul 17, 14:20 UTC | Jul 17, 17:30 UTC | 3h 10m |
| 2026-07-17 | WMT7BV | - | Jul 17, 11:50 UTC | Jul 17, 13:10 UTC | 1h 20m |
| 2026-07-17 | WMT7340 | - | Jul 17, 09:15 UTC | Jul 17, 10:44 UTC | 1h 30m |
| 2026-07-17 | WMT3662 | - | Jul 17, 06:50 UTC | Jul 17, 08:20 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-WAL page for operator, model, and routing details .
Mode-S 4D2421 frequently asked
What is Mode-S code 4D2421?
4D2421 is an ICAO 24-bit transponder address. Assigned to 9H-WAL.
Is 4D2421 broadcasting right now?
Yes. Mode-S 4D2421 is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 4D2421, octal 23222041, decimal 5,055,521.