sensors Mode-S transponder
4CAF51
ICAO 24-bit transponder address · allocated to Ireland
- Hex
- 4CAF51
- Octal
- 23127521
- Decimal
- 5,025,617
- Country
- IE
- Flights observed
- 22
- Distinct callsigns
- 18
- Country
- IE
- Last broadcast
- 22d ago
Last known position
Country allocation
The ICAO 24-bit address 4CAF51 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 18 distinct
| Callsign | Airline | Flights | Last seen |
|---|---|---|---|
| RYR91XZ | - | 2 | 2026-07-05 |
| RYR6CH | Ryanair | 2 | 2026-06-16 |
| RYR9503 | Ryanair | 1 | 2026-06-14 |
| RYR9078 | - | 1 | 2026-07-02 |
| RYR87SK | - | 1 | 2026-06-29 |
| RYR83AR | - | 1 | 2026-07-02 |
| RYR72SR | - | 1 | 2026-07-03 |
| RYR70CB | - | 1 | 2026-07-05 |
| RYR6814 | Ryanair | 1 | 2026-06-21 |
| RYR62ZH | - | 1 | 2026-07-03 |
| RYR562G | Ryanair | 1 | 2026-06-17 |
| RYR4SG | - | 1 | 2026-07-07 |
| RYR45JL | - | 1 | 2026-07-08 |
| RYR2976 | - | 1 | 2026-06-24 |
| RYR1QD | - | 1 | 2026-07-06 |
| RYR17PE | - | 1 | 2026-07-06 |
| RYR1315 | Ryanair | 1 | 2026-06-13 |
| RY42ZV | - | 1 | 2026-06-29 |
Recent flights last 22
| Date | Flight | Route | Takeoff | Landing | Duration |
|---|---|---|---|---|---|
| 2026-07-08 | RYR45JL | - | Jul 8, 17:30 UTC | Jul 8, 22:25 UTC | 4h 55m |
| 2026-07-07 | RYR4SG | - | Jul 7, 08:50 UTC | Jul 7, 22:00 UTC | 13h 10m |
| 2026-07-06 | RYR17PE | - | Jul 6, 17:50 UTC | Jul 6, 22:00 UTC | 4h 10m |
| 2026-07-06 | RYR1QD | - | Jul 6, 08:00 UTC | Jul 6, 16:00 UTC | 8h 0m |
| 2026-07-05 | RYR91XZ | - | Jul 5, 19:15 UTC | Jul 6, 16:00 UTC | 20h 45m |
| 2026-07-05 | RYR91XZ | - | Jul 5, 14:20 UTC | Jul 6, 10:00 UTC | 19h 40m |
| 2026-07-05 | RYR70CB | - | Jul 5, 05:05 UTC | Jul 5, 19:25 UTC | 14h 20m |
| 2026-07-03 | RYR62ZH | - | Jul 3, 17:40 UTC | Jul 3, 22:45 UTC | 5h 5m |
| 2026-07-03 | RYR72SR | - | Jul 3, 15:55 UTC | Jul 3, 16:10 UTC | 15m |
| 2026-07-02 | RYR83AR | - | Jul 2, 16:40 UTC | Jul 3, 11:20 UTC | 18h 40m |
| 2026-07-02 | RYR9078 | - | Jul 2, 09:55 UTC | Jul 2, 10:05 UTC | 10m |
| 2026-06-29 | RY42ZV | - | Jun 29, 20:59 UTC | Jun 29, 21:09 UTC | 10m |
| 2026-06-29 | RYR87SK | - | Jun 29, 19:05 UTC | Jun 29, 19:15 UTC | 10m |
| 2026-06-24 | RYR2976 | - | Jun 24, 13:34 UTC | Jun 24, 15:54 UTC | 2h 20m |
| 2026-06-21 | RYR6814 | MAN → MAD | Jun 21, 18:35 UTC | Jun 21, 18:44 UTC | 10m |
| 2026-06-17 | RYR562G | LPL → TFS | Jun 17, 14:30 UTC | Jun 17, 14:40 UTC | 10m |
| 2026-06-16 | - | - | Jun 16, 10:20 UTC | Jun 16, 10:30 UTC | 10m |
| 2026-06-16 | RYR6CH | BRS → RZE | Jun 16, 07:05 UTC | Jun 16, 07:15 UTC | 10m |
| 2026-06-16 | RYR6CH | BRS → RZE | Jun 16, 05:15 UTC | Jun 16, 05:25 UTC | 10m |
| 2026-06-14 | RYR9503 | BRS → BZG | Jun 14, 07:05 UTC | Jun 14, 07:15 UTC | 10m |
| 2026-06-13 | - | - | Jun 13, 11:45 UTC | Jun 13, 11:55 UTC | 10m |
| 2026-06-13 | RYR1315 | MRS → BRS | Jun 13, 10:05 UTC | Jun 13, 10:15 UTC | 10m |
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.