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
- Flights observed
- 66
- Distinct callsigns
- 20
- Country
- IE
- Last broadcast
- 1d ago
Last known position
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 |
|---|---|---|---|
| KZR553 | - | 9 | 2026-04-27 |
| KZR915 | Air Astana | 6 | 2026-05-15 |
| KZR557 | - | 6 | 2026-05-05 |
| KZR215 | Air Astana | 6 | 2026-05-23 |
| KZR907 | Air Astana | 5 | 2026-05-03 |
| KZR216 | Air Astana | 5 | 2026-05-23 |
| KZR963 | Air Astana | 4 | 2026-05-08 |
| KZR139 | Air Astana | 4 | 2026-05-15 |
| KZR908 | Air Astana | 3 | 2026-05-01 |
| KZR964 | Air Astana | 2 | 2026-05-08 |
| KZR916 | Air Astana | 2 | 2026-05-16 |
| KZR554 | - | 2 | 2026-04-27 |
| KZR142 | Air Astana | 2 | 2026-05-09 |
| KZR140 | Air Astana | 2 | 2026-05-11 |
| KZR912 | Air Astana | 1 | 2026-05-03 |
| KZR911 | Air Astana | 1 | 2026-05-03 |
| KZR558 | Air Astana | 1 | 2026-05-05 |
| KZR268 | Air Astana | 1 | 2026-05-17 |
| KZR267 | Air Astana | 1 | 2026-05-17 |
| KZR226 | Air Astana | 1 | 2026-05-28 |
Recent flights last 50
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-05-28 | KZR226 | AYT → NQZ | May 28, 09:30 UTC | May 28, 11:25 UTC | 1h 55m |
| 2026-05-28 | KZR225 | NQZ → AYT | May 28, 06:20 UTC | May 28, 08:10 UTC | 1h 50m |
| 2026-05-23 | KZR216 | AYT → NQZ | May 23, 08:35 UTC | May 23, 10:30 UTC | 1h 55m |
| 2026-05-23 | KZR215 | NQZ → AYT | May 23, 04:55 UTC | May 23, 07:05 UTC | 2h 10m |
| 2026-05-21 | KZR216 | AYT → NQZ | May 21, 09:40 UTC | May 21, 10:55 UTC | 1h 15m |
| 2026-05-21 | KZR216 | AYT → NQZ | May 21, 08:50 UTC | May 21, 09:05 UTC | 15m |
| 2026-05-21 | KZR215 | NQZ → AYT | May 21, 06:40 UTC | May 21, 07:00 UTC | 20m |
| 2026-05-21 | KZR215 | NQZ → AYT | May 21, 04:55 UTC | May 21, 05:55 UTC | 1h 0m |
| 2026-05-20 | KZR216 | AYT → NQZ | May 20, 08:45 UTC | May 20, 11:15 UTC | 2h 30m |
| 2026-05-19 | KZR215 | NQZ → AYT | May 19, 18:40 UTC | May 20, 07:00 UTC | 12h 21m |
| 2026-05-19 | KZR216 | AYT → NQZ | May 19, 08:40 UTC | May 19, 10:40 UTC | 2h 0m |
| 2026-05-19 | KZR215 | NQZ → AYT | May 19, 07:00 UTC | May 19, 07:20 UTC | 20m |
| 2026-05-19 | KZR215 | NQZ → AYT | May 19, 05:05 UTC | May 19, 06:15 UTC | 1h 10m |
| 2026-05-17 | KZR268 | PEK → ALA | May 17, 22:05 UTC | May 17, 22:30 UTC | 25m |
| 2026-05-17 | KZR267 | ALA → PEK | May 17, 20:10 UTC | May 17, 20:25 UTC | 15m |
| 2026-05-16 | KZR916 | AYT → ALA | May 16, 11:01 UTC | May 16, 13:01 UTC | 2h 0m |
| 2026-05-15 | KZR915 | ALA → AYT | May 15, 18:25 UTC | May 16, 09:21 UTC | 14h 56m |
| 2026-05-15 | KZR139 | ALA → TBS | May 15, 16:30 UTC | May 15, 17:00 UTC | 30m |
| 2026-05-11 | KZR140 | TBS → ALA | May 11, 18:40 UTC | May 11, 19:25 UTC | 45m |
| 2026-05-11 | KZR139 | ALA → TBS | May 11, 17:00 UTC | May 11, 17:25 UTC | 25m |
| 2026-05-10 | KZR139 | ALA → TBS | May 10, 18:49 UTC | May 11, 17:25 UTC | 22h 36m |
| 2026-05-10 | KZR140 | TBS → ALA | May 10, 18:39 UTC | May 10, 19:15 UTC | 35m |
| 2026-05-10 | KZR139 | ALA → TBS | May 10, 16:20 UTC | May 10, 16:59 UTC | 40m |
| 2026-05-09 | KZR142 | TBS → ALA | May 9, 10:55 UTC | May 9, 11:25 UTC | 30m |
| 2026-05-08 | KZR964 | DEL → ALA | May 8, 20:15 UTC | May 9, 09:35 UTC | 13h 20m |
| 2026-05-08 | KZR963 | ALA → DEL | May 8, 17:40 UTC | May 8, 18:30 UTC | 50m |
| 2026-05-07 | KZR142 | TBS → ALA | May 7, 09:50 UTC | May 7, 10:25 UTC | 35m |
| 2026-05-07 | KZR141 | ALA → TBS | May 7, 08:15 UTC | May 7, 08:35 UTC | 20m |
| 2026-05-06 | KZR964 | DEL → ALA | May 6, 20:30 UTC | May 6, 21:10 UTC | 40m |
| 2026-05-06 | KZR963 | ALA → DEL | May 6, 17:55 UTC | May 6, 18:35 UTC | 40m |
| 2026-05-05 | KZR558 | SSH → NQZ | May 5, 10:00 UTC | May 5, 13:10 UTC | 3h 10m |
| 2026-05-05 | KZR557 | - | May 5, 04:50 UTC | May 5, 07:45 UTC | 2h 55m |
| 2026-05-03 | KZR912 | IST → ALA | May 3, 20:40 UTC | May 3, 20:55 UTC | 15m |
| 2026-05-03 | KZR911 | ALA → IST | May 3, 06:35 UTC | May 3, 16:15 UTC | 9h 40m |
| 2026-05-03 | KZR907 | ALA → DEL | May 3, 04:15 UTC | May 3, 04:55 UTC | 40m |
| 2026-05-01 | KZR908 | DEL → ALA | May 1, 06:50 UTC | May 1, 07:35 UTC | 45m |
| 2026-05-01 | KZR907 | ALA → DEL | May 1, 04:10 UTC | May 1, 05:00 UTC | 50m |
| 2026-04-29 | KZR908 | DEL → ALA | Apr 29, 06:19 UTC | Apr 29, 06:59 UTC | 40m |
| 2026-04-29 | KZR907 | ALA → DEL | Apr 29, 03:40 UTC | Apr 29, 04:34 UTC | 55m |
| 2026-04-27 | KZR554 | - | Apr 27, 12:10 UTC | Apr 27, 15:20 UTC | 3h 10m |
| 2026-04-27 | KZR553 | - | Apr 27, 06:55 UTC | Apr 27, 10:05 UTC | 3h 10m |
| 2026-04-26 | KZR553 | - | Apr 26, 12:50 UTC | Apr 27, 10:05 UTC | 21h 15m |
| 2026-04-26 | KZR553 | - | Apr 26, 11:00 UTC | Apr 27, 10:05 UTC | 23h 5m |
| 2026-04-25 | KZR915 | ALA → AYT | Apr 25, 20:10 UTC | Apr 26, 09:40 UTC | 13h 30m |
| 2026-04-25 | KZR963 | ALA → DEL | Apr 25, 07:00 UTC | Apr 25, 18:25 UTC | 11h 25m |
| 2026-04-25 | KZR907 | ALA → DEL | Apr 25, 04:20 UTC | Apr 25, 05:05 UTC | 45m |
| 2026-04-23 | KZR908 | DEL → ALA | Apr 23, 07:05 UTC | Apr 23, 07:40 UTC | 35m |
| 2026-04-22 | KZR907 | ALA → DEL | Apr 22, 20:10 UTC | Apr 23, 05:35 UTC | 9h 25m |
| 2026-04-22 | KZR963 | ALA → DEL | Apr 22, 18:00 UTC | Apr 22, 18:35 UTC | 35m |
| 2026-04-21 | KZR557 | - | Apr 21, 04:00 UTC | Apr 21, 13:01 UTC | 9h 0m |
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 .