Apparatus

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sensors Mode-S transponder

4CAF23

ICAO 24-bit transponder address · allocated to Ireland

Currently assigned to EI-KDJ · AIRBUS A-321neo

Hex
4CAF23
Octal
23127443
Decimal
5,025,571
Country
IE
Tail
EI-KDJ
Type
A21N
No current signal · last broadcast 16h ago
Flights observed
148
Distinct callsigns
20
Country
IE
Last broadcast
16h ago

Last known position

Most recent position reported by Mode-S 4CAF23.

Country allocation

The ICAO 24-bit address 4CAF23 falls within the block assigned to Ireland (IE) by ICAO Annex 10, Volume III. Every aircraft registered in Ireland 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
KZR925 - 18 2026-07-12
KZR215 - 13 2026-07-11
KZR553 - 10 2026-06-22
KZR915 - 9 2026-07-08
KZR907 - 9 2026-06-30
KZR926 - 8 2026-07-13
KZR557 - 7 2026-06-09
KZR216 Air Astana 7 2026-06-11
KZR140 Air Astana 6 2026-07-06
KZR964 - 4 2026-07-03
KZR963 Air Astana 4 2026-05-08
KZR908 - 4 2026-06-18
KZR897 - 4 2026-07-07
KZR591 - 4 2026-07-10
KZR226 - 4 2026-07-09
KZR225 - 4 2026-07-08
KZR139 Air Astana 4 2026-05-15
KZR292 - 3 2026-07-01
KZR267 - 3 2026-07-05
KZR916 Air Astana 2 2026-05-16

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-13 KZR926 - Jul 13, 09:10 UTCJul 13, 11:05 UTC1h 55m
2026-07-12 KZR925 - Jul 12, 10:50 UTCJul 13, 07:40 UTC20h 50m
2026-07-12 KZR925 - Jul 12, 09:15 UTCJul 13, 07:40 UTC22h 25m
2026-07-12 KZR925 - Jul 12, 05:20 UTCJul 12, 07:45 UTC2h 25m
2026-07-11 KZR925 - Jul 11, 10:50 UTCJul 12, 07:45 UTC20h 55m
2026-07-11 KZR925 - Jul 11, 08:55 UTCJul 12, 07:45 UTC22h 50m
2026-07-11 KZR215 - Jul 11, 05:05 UTCJul 11, 07:30 UTC2h 25m
2026-07-10 KZR215 - Jul 10, 10:50 UTCJul 11, 07:30 UTC20h 40m
2026-07-10 KZR215 - Jul 10, 10:30 UTCJul 11, 07:30 UTC21h 1m
2026-07-10 KZR591 - Jul 10, 06:00 UTCJul 10, 08:25 UTC2h 25m
2026-07-09 KZR591 - Jul 9, 08:50 UTCJul 10, 08:25 UTC23h 35m
2026-07-09 KZR226 - Jul 9, 07:50 UTCJul 10, 06:40 UTC22h 50m
2026-07-08 KZR225 - Jul 8, 11:00 UTCJul 9, 06:15 UTC19h 15m
2026-07-08 KZR915 - Jul 8, 07:15 UTCJul 8, 09:30 UTC2h 15m
2026-07-07 KZR915 - Jul 7, 12:25 UTCJul 8, 09:30 UTC21h 5m
2026-07-07 KZR915 - Jul 7, 10:15 UTCJul 8, 08:35 UTC22h 20m
2026-07-07 KZR897 - Jul 7, 08:15 UTCJul 7, 08:25 UTC10m
2026-07-06 KZR140 TBS → ALA Jul 6, 18:35 UTCJul 7, 06:20 UTC11h 45m
2026-07-06 KZR140 TBS → ALA Jul 6, 16:35 UTCJul 6, 17:05 UTC30m
2026-07-05 KZR140 TBS → ALA Jul 5, 22:10 UTCJul 6, 17:05 UTC18h 55m
2026-07-05 KZR267 - Jul 5, 20:05 UTCJul 5, 20:25 UTC20m
2026-07-05 KZR926 - Jul 5, 09:45 UTCJul 5, 11:30 UTC1h 45m
2026-07-05 KZR925 - Jul 5, 05:25 UTCJul 5, 07:50 UTC2h 25m
2026-07-04 KZR925 - Jul 4, 12:25 UTCJul 5, 07:50 UTC19h 25m
2026-07-04 KZR925 - Jul 4, 10:15 UTCJul 5, 07:50 UTC21h 35m
2026-07-03 KZR964 - Jul 3, 20:15 UTCJul 4, 08:45 UTC12h 30m
2026-07-03 KZR926 - Jul 3, 09:15 UTCJul 3, 18:50 UTC9h 35m
2026-07-03 KZR925 - Jul 3, 05:25 UTCJul 3, 07:50 UTC2h 25m
2026-07-02 KZR925 - Jul 2, 10:50 UTCJul 3, 07:50 UTC21h 0m
2026-07-02 KZR925 - Jul 2, 09:20 UTCJul 3, 07:50 UTC22h 30m
2026-07-01 KZR925 - Jul 1, 20:15 UTCJul 2, 07:45 UTC11h 30m
2026-07-01 KZR292 - Jul 1, 00:45 UTCJul 1, 18:45 UTC18h 0m
2026-06-30 KZR291 DEL → BOM Jun 30, 06:45 UTCJun 30, 23:15 UTC16h 30m
2026-06-30 KZR907 - Jun 30, 04:15 UTCJun 30, 05:15 UTC1h 0m
2026-06-29 KZR907 BUS → DEL Jun 29, 07:55 UTCJun 30, 05:15 UTC21h 21m
2026-06-27 KZR169 ALA → BUS Jun 27, 10:40 UTCJun 28, 03:05 UTC16h 25m
2026-06-27 KZR897 - Jun 27, 06:30 UTCJun 27, 08:49 UTC2h 20m
2026-06-26 KZR897 - Jun 26, 10:50 UTCJun 27, 08:49 UTC22h 0m
2026-06-26 KZR926 AYT → ALA Jun 26, 09:35 UTCJun 27, 08:44 UTC23h 10m
2026-06-26 KZR926 AYT → ALA Jun 26, 07:20 UTCJun 27, 06:35 UTC23h 15m
2026-06-26 KZR925 ALA → AYT Jun 26, 05:35 UTCJun 26, 11:09 UTC5h 35m
2026-06-25 KZR925 ALA → AYT Jun 25, 10:50 UTCJun 26, 10:44 UTC23h 55m
2026-06-25 KZR926 AYT → ALA Jun 25, 09:10 UTCJun 26, 07:24 UTC22h 15m
2026-06-24 KZR925 ALA → AYT Jun 24, 18:20 UTCJun 25, 07:39 UTC13h 20m
2026-06-24 KZR140 TBS → ALA Jun 24, 16:40 UTCJun 24, 17:10 UTC30m
2026-06-23 KZR636 TGD → ALA Jun 23, 10:04 UTCJun 23, 12:49 UTC2h 45m
2026-06-22 KZR635 ALA → TGD Jun 22, 13:35 UTCJun 23, 08:09 UTC18h 35m
2026-06-22 KZR553 - Jun 22, 08:29 UTCJun 22, 11:35 UTC3h 5m
2026-06-20 KZR267 ALA → PEK Jun 20, 20:20 UTCJun 20, 20:34 UTC15m
2026-06-20 KZR898 - Jun 20, 10:34 UTCJun 20, 11:05 UTC30m

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 EI-KDJ page for operator, model, and routing details .

Mode-S 4CAF23 frequently asked

What is Mode-S code 4CAF23?
4CAF23 is an ICAO 24-bit transponder address. Allocated to Ireland. Assigned to EI-KDJ.
Where is Mode-S 4CAF23 registered?
Mode-S code 4CAF23 is allocated to Ireland (IE). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 4CAF23 broadcasting right now?
No active broadcast right now. Last signal was 16h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 4CAF23, octal 23127443, decimal 5,025,571.
What flights does 4CAF23 operate?
Mode-S 4CAF23 has broadcast 20 distinct callsigns, including KZR925, KZR215, KZR553, KZR915, KZR907.