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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
Broadcasting now · callsign AEZ2618 · 1,525 ft
Flights observed
482
Distinct callsigns
20
Country
MT
Last broadcast
Jul 26, 17:50 UTC

Current position

4D21CF is currently broadcasting. Map zoomed to live position.

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
AEZ519C - 11 2026-07-22
AEZ516C Aerial Transit Company 11 2026-07-23
AEZ31TR - 11 2026-07-11
AEZ20GR - 11 2026-07-07
AEZ514C - 10 2026-07-21
AEZ40GR - 10 2026-06-26
AEZ158C - 10 2026-07-22
AEZ157Q - 10 2026-07-20
AEZ139V Aerial Transit Company 10 2026-07-26
AEZ12RG - 10 2026-07-16
AEZ833J - 9 2026-07-26
AEZ8094 - 9 2026-07-15
AEZ7817 Aerial Transit Company 9 2026-07-10
AEZ7813 Aerial Transit Company 9 2026-07-23
AEZ60RG - 9 2026-06-21
AEZ500Q - 9 2026-06-26
AEZ47LG - 9 2026-07-15
AEZ318W - 9 2026-07-23
AEZ2616 - 9 2026-07-10
AEZ145N Aerial Transit Company 9 2026-06-24

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 AEZ833J - Jul 26, 16:55 UTCJul 26, 17:50 UTC55m
2026-07-26 AEZ131R FCO → OLB Jul 26, 12:00 UTCJul 26, 12:25 UTC25m
2026-07-26 AEZ7812 OLB → FCO Jul 26, 09:55 UTCJul 26, 10:20 UTC25m
2026-07-26 AEZ139V FCO → OLB Jul 26, 08:10 UTCJul 26, 08:30 UTC20m
2026-07-26 AEZ7810 OLB → FCO Jul 26, 05:25 UTCJul 26, 05:55 UTC30m
2026-07-25 AEZ839Y LIN → OLB Jul 25, 19:20 UTCJul 25, 20:05 UTC45m
2026-07-25 AEZ2631 LIN → OLB Jul 25, 14:20 UTCJul 25, 15:10 UTC50m
2026-07-25 AEZ2630 - Jul 25, 12:20 UTCJul 25, 13:00 UTC40m
2026-07-25 AEZ2629 LIN → OLB Jul 25, 09:20 UTCJul 25, 10:20 UTC1h 0m
2026-07-25 AEZ2628 OLB → LIN Jul 25, 07:20 UTCJul 25, 08:00 UTC40m
2026-07-24 AEZ833J LIN → OLB Jul 24, 16:50 UTCJul 24, 17:55 UTC1h 5m
2026-07-24 AEZ835L - Jul 24, 12:00 UTCJul 24, 12:55 UTC55m
2026-07-24 AEZ38TM - Jul 24, 09:25 UTCJul 24, 10:15 UTC50m
2026-07-24 AEZ836S LIN → OLB Jul 24, 07:15 UTCJul 24, 08:00 UTC45m
2026-07-24 AEZ389L OLB → LIN Jul 24, 05:10 UTCJul 24, 06:00 UTC50m
2026-07-23 AEZ318W - Jul 23, 11:55 UTCJul 23, 12:20 UTC25m
2026-07-23 AEZ7813 FCO → OLB Jul 23, 10:15 UTCJul 23, 10:40 UTC25m
2026-07-23 AEZ516C CTA → FCO Jul 23, 05:05 UTCJul 23, 06:00 UTC55m
2026-07-22 AEZ519C - Jul 22, 17:40 UTCJul 22, 18:35 UTC55m
2026-07-22 AEZ158C - Jul 22, 14:25 UTCJul 22, 15:10 UTC45m
2026-07-21 AEZ519C - Jul 21, 17:30 UTCJul 21, 18:30 UTC1h 0m
2026-07-21 AEZ158C - Jul 21, 14:15 UTCJul 21, 15:05 UTC50m
2026-07-21 AEZ514C - Jul 21, 10:00 UTCJul 21, 10:55 UTC55m
2026-07-21 AEZ155Z - Jul 21, 07:35 UTCJul 21, 08:25 UTC50m
2026-07-21 AEZ516C - Jul 21, 05:05 UTCJul 21, 06:05 UTC1h 0m
2026-07-20 AEZ157Q - Jul 20, 20:00 UTCJul 20, 20:45 UTC45m
2026-07-20 AEZ519C - Jul 20, 17:35 UTCJul 20, 18:35 UTC1h 0m
2026-07-20 AEZ158C - Jul 20, 14:10 UTCJul 20, 14:55 UTC45m
2026-07-20 AEZ514C - Jul 20, 10:00 UTCJul 20, 11:00 UTC1h 0m
2026-07-20 AEZ155Z - Jul 20, 08:05 UTCJul 20, 08:55 UTC50m
2026-07-20 AEZ516C - Jul 20, 05:10 UTCJul 20, 06:10 UTC1h 0m
2026-07-19 AEZ157Q - Jul 19, 20:20 UTCJul 19, 21:05 UTC45m
2026-07-19 AEZ519C - Jul 19, 17:45 UTCJul 19, 18:45 UTC1h 0m
2026-07-19 AEZ158C - Jul 19, 10:00 UTCJul 19, 10:45 UTC45m
2026-07-19 AEZ516C - Jul 19, 05:05 UTCJul 19, 06:05 UTC1h 0m
2026-07-18 AEZ157Q - Jul 18, 19:50 UTCJul 18, 20:35 UTC45m
2026-07-18 AEZ519C - Jul 18, 17:35 UTCJul 18, 18:35 UTC1h 0m
2026-07-18 AEZ158C - Jul 18, 14:00 UTCJul 18, 14:50 UTC50m
2026-07-18 AEZ514C - Jul 18, 09:55 UTCJul 18, 10:55 UTC1h 0m
2026-07-18 AEZ155Z - Jul 18, 07:35 UTCJul 18, 08:20 UTC45m
2026-07-18 AEZ516C - Jul 18, 05:20 UTCJul 18, 06:20 UTC1h 0m
2026-07-17 AEZ157Q - Jul 17, 20:55 UTCJul 17, 21:50 UTC55m
2026-07-17 AEZ519C - Jul 17, 18:05 UTCJul 17, 19:05 UTC1h 0m
2026-07-16 AEZ2349 - Jul 16, 20:29 UTCJul 16, 21:00 UTC30m
2026-07-16 AEZ70MH - Jul 16, 18:19 UTCJul 16, 19:05 UTC45m
2026-07-16 AEZ12RG - Jul 16, 15:55 UTCJul 16, 16:35 UTC40m
2026-07-16 AEZ22LO - Jul 16, 13:54 UTCJul 16, 14:29 UTC35m
2026-07-16 AEZ112X - Jul 16, 11:45 UTCJul 16, 12:09 UTC25m
2026-07-16 AEZ81GR - Jul 16, 08:35 UTCJul 16, 09:15 UTC40m
2026-07-15 AEZ2363 - Jul 15, 17:30 UTCJul 15, 18:30 UTC1h 0m

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?
Yes. Mode-S 4D21CF is currently airborne.
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 AEZ519C, AEZ516C, AEZ31TR, AEZ20GR, AEZ514C.