Apparatus

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sensors Mode-S transponder

4D21F1

ICAO 24-bit transponder address · allocated to Malta

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

Hex
4D21F1
Octal
23220761
Decimal
5,054,961
Country
MT
Tail
9H-QAI
Type
B738
No current signal · last broadcast 5h ago
Flights observed
596
Distinct callsigns
20
Country
MT
Last broadcast
5h ago

Last known position

Most recent position reported by Mode-S 4D21F1.

Country allocation

The ICAO 24-bit address 4D21F1 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
RYR8LM - 4 2026-07-08
RYR8124 - 4 2026-07-08
RYR20SB - 4 2026-07-12
RYR8UC Ryanair 3 2026-06-09
RYR8BT - 3 2026-06-20
RYR82UJ - 3 2026-04-16
RYR784B - 3 2026-07-10
RYR5SR - 3 2026-06-20
RYR59GQ Ryanair 3 2026-06-10
RYR59CJ Ryanair 3 2026-06-04
RYR4MT - 3 2026-04-16
RYR4KG - 3 2026-04-13
RYR48WU Ryanair 3 2026-06-10
RYR3631 Ryanair 3 2026-07-10
RYR29BC Ryanair 3 2026-05-20
RYR1994 - 3 2026-07-10
RYR17XU Ryanair 3 2026-05-20
RYR1795 Ryanair 3 2026-06-04
RYR16EA - 3 2026-07-10
RYR13KA Ryanair 3 2026-06-13

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-14 RYR5641 - Jul 14, 20:15 UTCJul 14, 21:25 UTC1h 10m
2026-07-14 RYR8KM - Jul 14, 16:50 UTCJul 14, 19:10 UTC2h 20m
2026-07-14 RYR6NG IBZ → STN Jul 14, 12:45 UTCJul 14, 14:45 UTC2h 0m
2026-07-14 RYR5NQ - Jul 14, 09:35 UTCJul 14, 11:50 UTC2h 15m
2026-07-13 RYR8FD - Jul 13, 19:05 UTCJul 13, 21:10 UTC2h 5m
2026-07-13 RYR1T - Jul 13, 15:50 UTCJul 13, 18:05 UTC2h 15m
2026-07-13 RYR5QM - Jul 13, 11:30 UTCJul 13, 14:50 UTC3h 20m
2026-07-13 RYR19AA - Jul 13, 07:45 UTCJul 13, 10:25 UTC2h 40m
2026-07-12 RYR1FE - Jul 12, 21:00 UTCJul 12, 21:50 UTC50m
2026-07-12 RYR4XC - Jul 12, 19:35 UTCJul 12, 20:10 UTC35m
2026-07-12 RYR4RZ TLS → STN Jul 12, 17:10 UTCJul 12, 18:35 UTC1h 25m
2026-07-12 RYR3838 MAN → TLS Jul 12, 14:45 UTCJul 12, 16:20 UTC1h 35m
2026-07-12 RYR3839 TLS → MAN Jul 12, 11:55 UTCJul 12, 13:35 UTC1h 40m
2026-07-12 RYR20SB TLS → TLS Jul 12, 04:25 UTCJul 12, 09:25 UTC5h 0m
2026-07-11 RYR72EU MAH → TLS Jul 11, 19:25 UTCJul 11, 20:20 UTC55m
2026-07-11 RYR7597 TLS → MAH Jul 11, 17:50 UTCJul 11, 18:40 UTC50m
2026-07-11 RYR34HL - Jul 11, 15:45 UTCJul 11, 17:00 UTC1h 15m
2026-07-11 RYR26LU TLS → CRL Jul 11, 13:30 UTCJul 11, 14:50 UTC1h 20m
2026-07-11 RYR2198 - Jul 11, 11:15 UTCJul 11, 12:40 UTC1h 25m
2026-07-11 RYR9BY - Jul 11, 08:40 UTCJul 11, 10:20 UTC1h 40m
2026-07-11 RYR13DX - Jul 11, 06:50 UTCJul 11, 07:55 UTC1h 5m
2026-07-11 RYR64SP TLS → BGY Jul 11, 04:25 UTCJul 11, 05:31 UTC1h 5m
2026-07-10 RYR693D LIS → TLS Jul 10, 20:30 UTCJul 10, 22:00 UTC1h 30m
2026-07-10 RYR32KG TLS → LIS Jul 10, 17:40 UTCJul 10, 19:25 UTC1h 45m
2026-07-10 RYR3631 TSF → TLS Jul 10, 15:20 UTCJul 10, 16:40 UTC1h 20m
2026-07-10 RYR16EA - Jul 10, 13:10 UTCJul 10, 14:35 UTC1h 25m
2026-07-10 RYR4214 - Jul 10, 11:05 UTCJul 10, 11:55 UTC50m
2026-07-10 RYR29UF - Jul 10, 09:20 UTCJul 10, 10:05 UTC45m
2026-07-10 RYR784B - Jul 10, 06:55 UTCJul 10, 08:30 UTC1h 35m
2026-07-10 RYR1994 - Jul 10, 04:40 UTCJul 10, 06:05 UTC1h 25m
2026-07-09 RYR4HL NDR → TLS Jul 9, 18:40 UTCJul 9, 20:05 UTC1h 25m
2026-07-09 RYR3157 - Jul 9, 16:25 UTCJul 9, 17:55 UTC1h 30m
2026-07-09 RYR3PP - Jul 9, 12:50 UTCJul 9, 14:55 UTC2h 5m
2026-07-09 RYR20SB - Jul 9, 09:45 UTCJul 9, 11:35 UTC1h 50m
2026-07-09 RYR8KB SVQ → TLS Jul 9, 07:20 UTCJul 9, 08:45 UTC1h 25m
2026-07-09 RYR1193 TLS → SVQ Jul 9, 05:10 UTCJul 9, 06:35 UTC1h 25m
2026-07-08 RYR4828 PFO → TLS Jul 8, 17:30 UTCJul 8, 21:10 UTC3h 40m
2026-07-08 RYR4829 TLS → PFO Jul 8, 13:00 UTCJul 8, 16:35 UTC3h 35m
2026-07-08 RYR8LM IBZ → TLS Jul 8, 10:55 UTCJul 8, 11:50 UTC55m
2026-07-08 RYR8124 - Jul 8, 09:05 UTCJul 8, 10:00 UTC55m
2026-07-08 RYR1BA - Jul 8, 06:40 UTCJul 8, 07:55 UTC1h 15m
2026-07-08 RYR8WQ - Jul 8, 04:15 UTCJul 8, 05:35 UTC1h 20m
2026-07-07 RYR779 - Jul 7, 18:50 UTCJul 7, 20:30 UTC1h 40m
2026-07-07 RYR778 - Jul 7, 15:55 UTCJul 7, 17:30 UTC1h 35m
2026-07-07 RYR2198 - Jul 7, 13:15 UTCJul 7, 14:45 UTC1h 30m
2026-07-07 RYR9BY TLS → TNG Jul 7, 10:30 UTCJul 7, 12:05 UTC1h 35m
2026-07-07 RYR90FN - Jul 7, 07:05 UTCJul 7, 09:05 UTC2h 0m
2026-07-07 RYR67RW TLS → MLA Jul 7, 04:15 UTCJul 7, 06:15 UTC2h 0m
2026-07-06 RYR829U KRK → TLS Jul 6, 18:30 UTCJul 6, 20:40 UTC2h 10m
2026-07-06 RYR523V TLS → KRK Jul 6, 15:25 UTCJul 6, 17:40 UTC2h 15m

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

Mode-S 4D21F1 frequently asked

What is Mode-S code 4D21F1?
4D21F1 is an ICAO 24-bit transponder address. Allocated to Malta. Assigned to 9H-QAI.
Where is Mode-S 4D21F1 registered?
Mode-S code 4D21F1 is allocated to Malta (MT). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 4D21F1 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 4D21F1, octal 23220761, decimal 5,054,961.
What flights does 4D21F1 operate?
Mode-S 4D21F1 has broadcast 20 distinct callsigns, including RYR8LM, RYR8124, RYR20SB, RYR8UC, RYR8BT.