Apparatus

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sensors Mode-S transponder

4D21CF

ICAO 24-bit transponder address · allocated to Malta

Currently assigned to 9H-FSJ · BOEING 737-800

Hex
4D21CF
Octal
23220717
Decimal
5,054,927
Country
MT
Tail
9H-FSJ
Type
B738
No current signal · last broadcast 5h ago
Flights observed
428
Distinct callsigns
20
Country
MT
Last broadcast
5h ago

Last known position

Most recent position reported by Mode-S 4D21CF.

Country allocation

The ICAO 24-bit address 4D21CF 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 20 distinct

Callsign Airline Flights Last seen
AEZ31TR - 11 2026-07-11
AEZ20GR - 11 2026-07-07
AEZ40GR - 10 2026-06-26
AEZ7817 Aerial Transit Company 9 2026-07-10
AEZ60RG - 9 2026-06-21
AEZ500Q - 9 2026-06-26
AEZ2616 - 9 2026-07-10
AEZ145N Aerial Transit Company 9 2026-06-24
AEZ139V - 9 2026-07-14
AEZ12RG - 9 2026-07-03
AEZ8094 - 8 2026-07-05
AEZ7814 - 8 2026-07-10
AEZ7813 - 8 2026-07-11
AEZ569P - 8 2026-07-11
AEZ47LG Aerial Transit Company 8 2026-06-15
AEZ418P - 8 2026-06-24
AEZ318W - 8 2026-07-11
AEZ29JD Aerial Transit Company 8 2026-07-13
AEZ835L Aerial Transit Company 7 2026-07-13
AEZ833J - 7 2026-07-13

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-14 AEZ11LJ FCO → CAG Jul 14, 16:35 UTCJul 14, 17:20 UTC45m
2026-07-14 AEZ7812 - Jul 14, 09:40 UTCJul 14, 10:00 UTC20m
2026-07-14 AEZ139V - Jul 14, 07:45 UTCJul 14, 08:05 UTC20m
2026-07-14 AEZ7810 OLB → FCO Jul 14, 05:05 UTCJul 14, 05:40 UTC35m
2026-07-13 AEZ833J LIN → OLB Jul 13, 16:40 UTCJul 13, 17:35 UTC55m
2026-07-13 AEZ29JD OLB → LIN Jul 13, 14:55 UTCJul 13, 15:40 UTC45m
2026-07-13 AEZ835L LIN → OLB Jul 13, 12:25 UTCJul 13, 13:25 UTC1h 0m
2026-07-13 AEZ41ST - Jul 13, 09:55 UTCJul 13, 10:55 UTC1h 0m
2026-07-13 AEZ8662 - Jul 13, 07:40 UTCJul 13, 08:30 UTC50m
2026-07-13 AEZ389L OLB → LIN Jul 13, 05:15 UTCJul 13, 06:10 UTC55m
2026-07-12 AEZ833J LIN → OLB Jul 12, 17:20 UTCJul 12, 18:20 UTC1h 0m
2026-07-12 AEZ29JD OLB → LIN Jul 12, 14:50 UTCJul 12, 15:45 UTC55m
2026-07-12 AEZ835L LIN → OLB Jul 12, 11:50 UTCJul 12, 12:40 UTC50m
2026-07-12 AEZ38TM - Jul 12, 09:25 UTCJul 12, 10:10 UTC45m
2026-07-12 AEZ836S - Jul 12, 07:01 UTCJul 12, 07:55 UTC55m
2026-07-12 AEZ389L - Jul 12, 05:01 UTCJul 12, 05:45 UTC45m
2026-07-11 AEZ839Y - Jul 11, 21:10 UTCJul 11, 22:05 UTC55m
2026-07-11 AEZ569P - Jul 11, 17:45 UTCJul 11, 18:20 UTC35m
2026-07-11 AEZ318W - Jul 11, 11:40 UTCJul 11, 12:15 UTC35m
2026-07-11 AEZ7813 - Jul 11, 09:55 UTCJul 11, 10:30 UTC35m
2026-07-11 AEZ31TR - Jul 11, 07:50 UTCJul 11, 08:20 UTC30m
2026-07-11 AEZ7811 - Jul 11, 05:55 UTCJul 11, 06:25 UTC30m
2026-07-10 AEZ2616 - Jul 10, 19:30 UTCJul 10, 20:00 UTC30m
2026-07-10 AEZ7817 FCO → OLB Jul 10, 17:45 UTCJul 10, 18:15 UTC30m
2026-07-10 AEZ7814 - Jul 10, 15:50 UTCJul 10, 16:15 UTC25m
2026-07-10 AEZ7815 FCO → OLB Jul 10, 14:15 UTCJul 10, 14:45 UTC30m
2026-07-10 AEZ318W - Jul 10, 12:00 UTCJul 10, 12:35 UTC35m
2026-07-10 AEZ7813 - Jul 10, 10:05 UTCJul 10, 10:40 UTC35m
2026-07-10 AEZ31TR - Jul 10, 07:55 UTCJul 10, 08:35 UTC40m
2026-07-10 AEZ7811 - Jul 10, 06:05 UTCJul 10, 06:40 UTC35m
2026-07-09 AEZ2616 - Jul 9, 19:45 UTCJul 9, 20:15 UTC30m
2026-07-09 AEZ7817 FCO → OLB Jul 9, 18:05 UTCJul 9, 18:45 UTC40m
2026-07-09 AEZ9081 - Jul 9, 15:05 UTCJul 9, 15:40 UTC35m
2026-07-09 AEZ2081 - Jul 9, 11:45 UTCJul 9, 13:25 UTC1h 40m
2026-07-09 AEZ2080 - Jul 9, 09:15 UTCJul 9, 10:45 UTC1h 30m
2026-07-08 AEZ9347 - Jul 8, 20:55 UTCJul 8, 21:30 UTC35m
2026-07-07 AEZ9610 - Jul 7, 08:00 UTCJul 7, 08:35 UTC35m
2026-07-07 AEZ20GR - Jul 7, 05:45 UTCJul 7, 06:20 UTC35m
2026-07-06 AEZ2363 - Jul 6, 17:15 UTCJul 6, 18:10 UTC55m
2026-07-06 AEZ88LL LIN → CAG Jul 6, 12:45 UTCJul 6, 13:45 UTC1h 0m
2026-07-06 AEZ44LG - Jul 6, 06:20 UTCJul 6, 07:15 UTC55m
2026-07-05 AEZ2363 - Jul 5, 18:00 UTCJul 5, 18:55 UTC55m
2026-07-05 AEZ88LL LIN → CAG Jul 5, 13:25 UTCJul 5, 14:20 UTC55m
2026-07-05 AEZ8094 - Jul 5, 08:40 UTCJul 5, 09:30 UTC50m
2026-07-04 AEZ81GR - Jul 4, 08:40 UTCJul 4, 09:25 UTC45m
2026-07-04 AEZ300Z - Jul 4, 06:20 UTCJul 4, 06:50 UTC30m
2026-07-03 AEZ12RG - Jul 3, 16:05 UTCJul 3, 16:35 UTC30m
2026-07-03 AEZ22LO - Jul 3, 13:55 UTCJul 3, 14:40 UTC45m
2026-07-03 AEZ112X FCO → CAG Jul 3, 10:45 UTCJul 3, 11:05 UTC20m
2026-07-03 AEZ48LG - Jul 3, 04:20 UTCJul 3, 05:15 UTC55m

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-FSJ page for operator, model, and routing details .

Mode-S 4D21CF frequently asked

What is Mode-S code 4D21CF?
4D21CF is an ICAO 24-bit transponder address. Allocated to Malta. Assigned to 9H-FSJ.
Where is Mode-S 4D21CF registered?
Mode-S code 4D21CF is allocated to Malta (MT). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 4D21CF broadcasting right now?
No active broadcast right now. Last signal was 5h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 4D21CF, octal 23220717, decimal 5,054,927.
What flights does 4D21CF operate?
Mode-S 4D21CF has broadcast 20 distinct callsigns, including AEZ31TR, AEZ20GR, AEZ40GR, AEZ7817, AEZ60RG.