Apparatus

Try JFK, AAL1290, BAW, or N225AN.

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 Jul 26, 20:25 UTC
Flights observed
684
Distinct callsigns
20
Country
MT
Last broadcast
Jul 26, 20:25 UTC

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
RYR9WK Ryanair 7 2026-07-26
RYR6WH Ryanair 7 2026-07-26
RYR4LW - 7 2026-07-26
RYR319 Ryanair 7 2026-07-26
RYR26LR Ryanair 6 2026-07-26
RYR9F - 5 2026-07-25
RYR7404 Ryanair 5 2026-07-25
RYR4982 Ryanair 5 2026-07-26
RYR8LM - 4 2026-07-08
RYR8124 - 4 2026-07-08
RYR5641 - 4 2026-07-25
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
RYR71XU - 3 2026-07-24
RYR66SW - 3 2026-07-25
RYR5SR - 3 2026-06-20
RYR59GQ Ryanair 3 2026-06-10

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 RYR6WH ATH → CHQ Jul 26, 20:00 UTCJul 26, 20:25 UTC25m
2026-07-26 RYR319 MAD → MRS Jul 26, 18:10 UTCJul 26, 18:45 UTC35m
2026-07-26 RYR4982 SKG → CHQ Jul 26, 16:35 UTCJul 26, 17:20 UTC45m
2026-07-26 RYR26LR CHQ → SKG Jul 26, 14:15 UTCJul 26, 15:15 UTC1h 0m
2026-07-26 RYR4LW - Jul 26, 12:25 UTCJul 26, 13:25 UTC1h 0m
2026-07-26 RYR9WK CHQ → SOF Jul 26, 10:00 UTCJul 26, 11:05 UTC1h 5m
2026-07-26 RYR9SY VCE → MAN Jul 26, 08:00 UTCJul 26, 09:10 UTC1h 10m
2026-07-26 RYR9715 DUB → GNB Jul 26, 04:20 UTCJul 26, 05:40 UTC1h 20m
2026-07-25 RYR7404 MLA → CHQ Jul 25, 20:35 UTCJul 25, 21:35 UTC1h 0m
2026-07-25 RYR9F - Jul 25, 18:05 UTCJul 25, 19:25 UTC1h 20m
2026-07-25 RYR5641 - Jul 25, 16:10 UTCJul 25, 17:10 UTC1h 0m
2026-07-25 RYR66SW - Jul 25, 13:15 UTCJul 25, 14:30 UTC1h 15m
2026-07-25 RYR340A BGY → CHQ Jul 25, 10:20 UTCJul 25, 12:15 UTC1h 55m
2026-07-25 RYR4HB HAM → VLC Jul 25, 06:50 UTCJul 25, 09:05 UTC2h 15m
2026-07-25 RYR4982 SKG → CHQ Jul 25, 04:55 UTCJul 25, 05:35 UTC40m
2026-07-25 RYR26LR CHQ → SKG Jul 25, 03:00 UTCJul 25, 03:55 UTC55m
2026-07-24 RYR5084 PFO → CHQ Jul 24, 20:10 UTCJul 24, 21:10 UTC1h 0m
2026-07-24 RYR71XU - Jul 24, 17:10 UTCJul 24, 18:05 UTC55m
2026-07-24 RYR4LW - Jul 24, 14:50 UTCJul 24, 16:00 UTC1h 10m
2026-07-24 RYR9WK CHQ → SOF Jul 24, 12:50 UTCJul 24, 13:50 UTC1h 0m
2026-07-24 RYR1WN DUB → OTP Jul 24, 09:35 UTCJul 24, 11:20 UTC1h 45m
2026-07-24 RYR42PQ CHQ → BUD Jul 24, 06:05 UTCJul 24, 07:50 UTC1h 45m
2026-07-24 RYR6WH ATH → CHQ Jul 24, 04:40 UTCJul 24, 05:05 UTC25m
2026-07-24 RYR319 MAD → MRS Jul 24, 02:45 UTCJul 24, 03:15 UTC30m
2026-07-23 RYR5335 - Jul 23, 20:40 UTCJul 23, 21:25 UTC45m
2026-07-23 RYR50EX - Jul 23, 18:05 UTCJul 23, 19:00 UTC55m
2026-07-23 RYR11HW NAP → CHQ Jul 23, 15:45 UTCJul 23, 16:45 UTC1h 0m
2026-07-23 RYR3SX STN → BCN Jul 23, 11:55 UTCJul 23, 13:35 UTC1h 40m
2026-07-23 RYR1AK KIR → DUB Jul 23, 08:45 UTCJul 23, 10:50 UTC2h 5m
2026-07-23 RYR9ZE FCO → PMO Jul 23, 04:25 UTCJul 23, 06:40 UTC2h 15m
2026-07-22 RYR4LW - Jul 22, 22:00 UTCJul 22, 23:10 UTC1h 10m
2026-07-22 RYR9WK CHQ → SOF Jul 22, 20:00 UTCJul 22, 21:10 UTC1h 10m
2026-07-22 RYR6WH ATH → CHQ Jul 22, 18:45 UTCJul 22, 19:15 UTC30m
2026-07-22 RYR319 MAD → MRS Jul 22, 17:15 UTCJul 22, 17:55 UTC40m
2026-07-22 RYR4982 SKG → CHQ Jul 22, 14:10 UTCJul 22, 15:00 UTC50m
2026-07-22 RYR26LR CHQ → SKG Jul 22, 11:55 UTCJul 22, 12:45 UTC50m
2026-07-21 RYR5641 - Jul 21, 21:25 UTCJul 21, 22:40 UTC1h 15m
2026-07-21 RYR66SW - Jul 21, 19:00 UTCJul 21, 20:25 UTC1h 25m
2026-07-21 RYR6WH ATH → CHQ Jul 21, 17:25 UTCJul 21, 18:00 UTC35m
2026-07-21 RYR319 MAD → MRS Jul 21, 13:30 UTCJul 21, 14:05 UTC35m
2026-07-21 RYR7404 MLA → CHQ Jul 21, 11:10 UTCJul 21, 12:25 UTC1h 15m
2026-07-21 RYR9F - Jul 21, 07:10 UTCJul 21, 08:25 UTC1h 15m
2026-07-21 RYR4LW - Jul 21, 05:15 UTCJul 21, 06:20 UTC1h 5m
2026-07-21 RYR9WK CHQ → SOF Jul 21, 02:50 UTCJul 21, 03:55 UTC1h 5m
2026-07-20 RYR5084 - Jul 20, 17:40 UTCJul 20, 18:40 UTC1h 0m
2026-07-20 RYR71XU - Jul 20, 15:05 UTCJul 20, 16:10 UTC1h 5m
2026-07-20 RYR7404 MLA → CHQ Jul 20, 13:00 UTCJul 20, 14:20 UTC1h 20m
2026-07-20 RYR9F - Jul 20, 09:40 UTCJul 20, 10:55 UTC1h 15m
2026-07-20 RYR11HW NAP → CHQ Jul 20, 07:20 UTCJul 20, 08:50 UTC1h 30m
2026-07-20 RYR3SX STN → BCN Jul 20, 04:20 UTCJul 20, 05:40 UTC1h 20m

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 Jul 26, 20:25 UTC.
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 RYR9WK, RYR6WH, RYR4LW, RYR319, RYR26LR.