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 8h ago
Flights observed
202
Distinct callsigns
20
Country
MT
Last broadcast
8h 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

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-05-30 AEZ516C CTA → FCO May 30, 05:05 UTCMay 30, 06:00 UTC55m
2026-05-29 AEZ157Q FCO → CTA May 29, 19:45 UTCMay 29, 20:35 UTC50m
2026-05-29 AEZ519C CTA → FCO May 29, 17:30 UTCMay 29, 18:25 UTC55m
2026-05-29 AEZ2824 BGY → CTA May 29, 14:55 UTCMay 29, 16:15 UTC1h 20m
2026-05-29 AEZ2825 CTA → BGY May 29, 12:00 UTCMay 29, 13:25 UTC1h 25m
2026-05-29 AEZ155Z FCO → CTA May 29, 07:35 UTCMay 29, 08:25 UTC50m
2026-05-29 AEZ419P PMO → FCO May 29, 05:30 UTCMay 29, 06:10 UTC40m
2026-05-28 AEZ146R FCO → PMO May 28, 19:40 UTCMay 28, 20:20 UTC40m
2026-05-28 AEZ418P PMO → FCO May 28, 17:20 UTCMay 28, 18:10 UTC50m
2026-05-28 AEZ145N FCO → PMO May 28, 14:10 UTCMay 28, 14:50 UTC40m
2026-05-28 AEZ60RG CAG → FCO May 28, 10:05 UTCMay 28, 10:45 UTC40m
2026-05-28 AEZ7117 - May 28, 08:05 UTCMay 28, 08:40 UTC35m
2026-05-28 AEZ20GR CAG → FCO May 28, 05:55 UTCMay 28, 06:40 UTC45m
2026-05-27 AEZ2362 CAG → LIN May 27, 15:50 UTCMay 27, 16:45 UTC55m
2026-05-27 AEZ47LG CAG → LIN May 27, 10:50 UTCMay 27, 11:50 UTC1h 0m
2026-05-27 AEZ8094 LIN → CAG May 27, 08:30 UTCMay 27, 09:25 UTC55m
2026-05-26 AEZ2367 LIN → CAG May 26, 20:09 UTCMay 26, 21:00 UTC50m
2026-05-26 AEZ49KF CAG → LIN May 26, 18:19 UTCMay 26, 19:15 UTC55m
2026-05-26 AEZ12RG FCO → CAG May 26, 16:15 UTCMay 26, 16:40 UTC25m
2026-05-26 AEZ11GR CAG → FCO May 26, 11:20 UTCMay 26, 11:54 UTC35m
2026-05-26 AEZ8041 LIN → CAG May 26, 06:29 UTCMay 26, 07:24 UTC55m
2026-05-26 AEZ48LG CAG → LIN May 26, 04:15 UTCMay 26, 05:10 UTC55m
2026-05-25 AEZ47LG CAG → LIN May 25, 10:50 UTCMay 25, 11:50 UTC1h 0m
2026-05-25 AEZ8094 LIN → CAG May 25, 08:30 UTCMay 25, 09:20 UTC50m
2026-05-24 AEZ7814 OLB → FCO May 24, 16:05 UTCMay 24, 16:30 UTC25m
2026-05-24 AEZ318W OLB → FCO May 24, 11:45 UTCMay 24, 12:15 UTC30m
2026-05-23 AEZ839Y LIN → OLB May 23, 19:55 UTCMay 23, 20:35 UTC40m
2026-05-23 AEZ385Z OLB → LIN May 23, 18:10 UTCMay 23, 19:00 UTC50m
2026-05-23 AEZ833J LIN → OLB May 23, 16:05 UTCMay 23, 16:50 UTC45m
2026-05-23 AEZ29JD OLB → LIN May 23, 14:15 UTCMay 23, 15:00 UTC45m
2026-05-23 AEZ835L LIN → OLB May 23, 11:55 UTCMay 23, 12:40 UTC45m
2026-05-23 AEZ38TM OLB → LIN May 23, 09:35 UTCMay 23, 10:20 UTC45m
2026-05-23 AEZ836S LIN → OLB May 23, 07:20 UTCMay 23, 08:10 UTC50m
2026-05-23 AEZ389L OLB → LIN May 23, 05:10 UTCMay 23, 05:55 UTC45m
2026-05-22 AEZ2617 FCO → OLB May 22, 20:15 UTCMay 22, 20:55 UTC40m
2026-05-22 AEZ2616 OLB → FCO May 22, 18:25 UTCMay 22, 19:00 UTC35m
2026-05-22 AEZ7817 FCO → OLB May 22, 16:50 UTCMay 22, 17:20 UTC30m
2026-05-22 AEZ514C CTA → FCO May 22, 14:40 UTCMay 22, 15:35 UTC55m
2026-05-22 AEZ158C FCO → CTA May 22, 12:20 UTCMay 22, 13:10 UTC50m
2026-05-22 AEZ60RG CAG → FCO May 22, 10:15 UTCMay 22, 10:55 UTC40m
2026-05-22 AEZ7117 - May 22, 08:40 UTCMay 22, 09:05 UTC25m
2026-05-22 AEZ20GR CAG → FCO May 22, 06:15 UTCMay 22, 06:50 UTC35m
2026-05-21 AEZ811Z - May 21, 13:20 UTCMay 21, 13:55 UTC35m
2026-05-21 AEZ11GR CAG → FCO May 21, 11:10 UTCMay 21, 12:00 UTC50m
2026-05-21 AEZ500Q FCO → CAG May 21, 09:15 UTCMay 21, 09:45 UTC30m
2026-05-21 AEZ40GR CAG → FCO May 21, 07:25 UTCMay 21, 08:05 UTC40m
2026-05-21 AEZ100N FCO → CAG May 21, 05:15 UTCMay 21, 05:40 UTC25m
2026-05-20 AEZ2348 CAG → FCO May 20, 19:45 UTCMay 20, 20:30 UTC45m
2026-05-20 AEZ811Z - May 20, 13:30 UTCMay 20, 14:00 UTC30m
2026-05-20 AEZ11GR CAG → FCO May 20, 11:10 UTCMay 20, 11:55 UTC45m

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 8h 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 AEZ20GR, AEZ60RG, AEZ31TR, AEZ12RG, AEZ7813.