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 Jul 26, 10:30 UTC
Flights observed
173
Distinct callsigns
20
Country
IE
Last broadcast
Jul 26, 10:30 UTC

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 - 21 2026-07-18
KZR215 - 13 2026-07-11
KZR553 - 10 2026-06-22
KZR915 - 9 2026-07-08
KZR907 - 9 2026-06-30
KZR557 - 8 2026-07-22
KZR926 - 7 2026-07-05
KZR591 - 7 2026-07-14
KZR216 Air Astana 7 2026-06-11
KZR8244 Air Astana 6 2026-07-25
KZR140 Air Astana 6 2026-07-06
KZR226 Air Astana 5 2026-07-21
KZR225 Air Astana 5 2026-07-21
KZR139 Air Astana 5 2026-07-25
KZR964 - 4 2026-07-03
KZR963 Air Astana 4 2026-05-08
KZR908 - 4 2026-06-18
KZR897 - 4 2026-07-07
KZR592 - 4 2026-07-14
KZR292 - 3 2026-07-01

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-26 KZR8245 AYT → ALA Jul 26, 08:40 UTCJul 26, 10:30 UTC1h 50m
2026-07-25 KZR8244 ALA → AYT Jul 25, 18:45 UTCJul 26, 06:40 UTC11h 56m
2026-07-25 KZR139 ALA → TBS Jul 25, 16:45 UTCJul 25, 17:25 UTC40m
2026-07-23 KZR558 SSH → NQZ Jul 23, 06:55 UTCJul 23, 09:20 UTC2h 25m
2026-07-22 KZR557 - Jul 22, 12:15 UTCJul 23, 04:40 UTC16h 25m
2026-07-21 KZR226 AYT → NQZ Jul 21, 08:05 UTCJul 21, 09:55 UTC1h 50m
2026-07-21 KZR225 NQZ → AYT Jul 21, 04:15 UTCJul 21, 06:05 UTC1h 50m
2026-07-20 KZR590 - Jul 20, 08:50 UTCJul 21, 06:05 UTC21h 15m
2026-07-20 KZR590 - Jul 20, 08:35 UTCJul 21, 06:05 UTC21h 30m
2026-07-19 KZR589 - Jul 19, 19:50 UTCJul 20, 06:50 UTC11h 0m
2026-07-19 KZR8245 AYT → ALA Jul 19, 08:45 UTCJul 19, 18:35 UTC9h 50m
2026-07-19 KZR8244 ALA → AYT Jul 19, 04:50 UTCJul 19, 07:15 UTC2h 25m
2026-07-18 KZR8244 ALA → AYT Jul 18, 09:05 UTCJul 19, 07:15 UTC22h 10m
2026-07-18 KZR8244 ALA → AYT Jul 18, 08:20 UTCJul 19, 06:45 UTC22h 25m
2026-07-18 KZR925 - Jul 18, 03:50 UTCJul 18, 06:15 UTC2h 25m
2026-07-17 KZR925 - Jul 17, 09:04 UTCJul 18, 06:15 UTC21h 11m
2026-07-17 KZR925 - Jul 17, 08:10 UTCJul 18, 06:15 UTC22h 6m
2026-07-16 KZR8244 ALA → AYT Jul 16, 12:25 UTCJul 17, 06:45 UTC18h 20m
2026-07-16 KZR8244 ALA → AYT Jul 16, 10:10 UTCJul 17, 06:45 UTC20h 35m
2026-07-15 KZR662 - Jul 15, 12:50 UTCJul 16, 08:30 UTC19h 40m
2026-07-15 KZR661 - Jul 15, 08:45 UTCJul 15, 11:15 UTC2h 30m
2026-07-14 KZR592 - Jul 14, 10:50 UTCJul 15, 10:45 UTC23h 54m
2026-07-14 KZR592 - Jul 14, 10:40 UTCJul 15, 08:45 UTC22h 4m
2026-07-14 KZR591 - Jul 14, 06:05 UTCJul 14, 08:35 UTC2h 30m
2026-07-13 KZR591 - Jul 13, 10:50 UTCJul 14, 08:35 UTC21h 45m
2026-07-13 KZR591 - Jul 13, 09:10 UTCJul 14, 08:35 UTC23h 25m
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

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 Jul 26, 10:30 UTC.
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.