Apparatus

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sensors Mode-S transponder

4CAD51

ICAO 24-bit transponder address · allocated to Ireland

Currently assigned to EI-HDK · ATR-72-600

Hex
4CAD51
Octal
23126521
Decimal
5,025,105
Country
IE
Tail
EI-HDK
Type
AT76
No current signal · last broadcast 8h ago
Flights observed
711
Distinct callsigns
20
Country
IE
Last broadcast
8h ago

Last known position

Most recent position reported by Mode-S 4CAD51.

Country allocation

The ICAO 24-bit address 4CAD51 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
EAI09U - 17 2026-07-12
EAI8C Elite Air 16 2026-07-12
EAI73N - 15 2026-07-13
EAI93D Elite Air 14 2026-07-09
EAI69M - 13 2026-07-11
EAI51C - 13 2026-07-01
EAI38D - 13 2026-07-11
EAI33S Elite Air 13 2026-07-06
EAI31Q Elite Air 13 2026-07-06
EAI95C Elite Air 12 2026-06-14
EAI92B Elite Air 12 2026-07-09
EAI50E - 12 2026-07-01
EAI42A - 12 2026-07-08
EAI37E - 12 2026-07-13
EAI2DM Elite Air 12 2026-07-08
EAI29GA - 12 2026-07-08
EAI26PK - 12 2026-07-08
EAI8BR - 11 2026-07-04
EAI81A - 11 2026-07-04
EAI53BS Elite Air 11 2026-07-07

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-13 EAI89DF BRS → DUB Jul 13, 19:45 UTCJul 13, 20:45 UTC1h 0m
2026-07-13 EAI17C ORK → BRS Jul 13, 17:55 UTCJul 13, 19:00 UTC1h 5m
2026-07-13 EAI18K BRS → ORK Jul 13, 16:00 UTCJul 13, 17:05 UTC1h 5m
2026-07-13 EAI86W DUB → BRS Jul 13, 14:10 UTCJul 13, 15:05 UTC55m
2026-07-13 EAI65Y - Jul 13, 12:10 UTCJul 13, 13:10 UTC1h 0m
2026-07-13 EAI64B DUB → BHX Jul 13, 10:20 UTCJul 13, 11:15 UTC55m
2026-07-13 EAI37E - Jul 13, 08:20 UTCJul 13, 09:25 UTC1h 5m
2026-07-13 EAI73N DUB → NCL Jul 13, 06:35 UTCJul 13, 07:30 UTC55m
2026-07-12 EAI09U SOU → DUB Jul 12, 19:40 UTCJul 12, 21:00 UTC1h 20m
2026-07-12 EAI8C DUB → SOU Jul 12, 17:25 UTCJul 12, 18:45 UTC1h 20m
2026-07-12 EAI89W NCL → DUB Jul 12, 15:45 UTCJul 12, 16:45 UTC1h 0m
2026-07-12 EAI79D DUB → NCL Jul 12, 13:50 UTCJul 12, 14:45 UTC55m
2026-07-12 EAI71G NQY → DUB Jul 12, 11:55 UTCJul 12, 12:50 UTC55m
2026-07-12 EAI62N DUB → NQY Jul 12, 10:25 UTCJul 12, 11:15 UTC50m
2026-07-12 EAI37E - Jul 12, 08:05 UTCJul 12, 09:15 UTC1h 10m
2026-07-12 EAI73N DUB → NCL Jul 12, 06:30 UTCJul 12, 07:20 UTC50m
2026-07-11 EAI7B BES → DUB Jul 11, 16:00 UTCJul 11, 17:35 UTC1h 35m
2026-07-11 EAI6F DUB → BES Jul 11, 13:45 UTCJul 11, 15:20 UTC1h 35m
2026-07-11 EAI38D MAN → DUB Jul 11, 11:55 UTCJul 11, 12:45 UTC50m
2026-07-11 EAI69M DUB → MAN Jul 11, 10:10 UTCJul 11, 10:50 UTC40m
2026-07-11 EAI91M - Jul 11, 08:01 UTCJul 11, 08:55 UTC55m
2026-07-11 EAI9L - Jul 11, 06:25 UTCJul 11, 07:20 UTC55m
2026-07-10 EAI73B BHX → DUB Jul 10, 16:55 UTCJul 10, 17:55 UTC1h 0m
2026-07-10 EAI72V DUB → BHX Jul 10, 14:20 UTCJul 10, 15:30 UTC1h 10m
2026-07-10 EAI39V LPL → DUB Jul 10, 12:15 UTCJul 10, 13:05 UTC50m
2026-07-10 EAI19L DUB → LPL Jul 10, 10:45 UTCJul 10, 11:25 UTC40m
2026-07-10 EAI23GA GLA → DUB Jul 10, 08:45 UTCJul 10, 09:45 UTC1h 0m
2026-07-10 EAI25G DUB → GLA Jul 10, 07:10 UTCJul 10, 08:00 UTC50m
2026-07-09 EAI09U SOU → DUB Jul 9, 19:55 UTCJul 9, 21:10 UTC1h 15m
2026-07-09 EAI8C DUB → SOU Jul 9, 18:00 UTCJul 9, 19:15 UTC1h 15m
2026-07-09 EAI93D LBA → LBA Jul 9, 16:15 UTCJul 9, 17:10 UTC55m
2026-07-09 EAI92B DUB → LBA Jul 9, 14:25 UTCJul 9, 15:15 UTC50m
2026-07-09 EAI65Y - Jul 9, 12:15 UTCJul 9, 13:10 UTC55m
2026-07-09 EAI64B DUB → BHX Jul 9, 10:15 UTCJul 9, 11:15 UTC1h 0m
2026-07-09 EAI37E NCL → DUB Jul 9, 08:15 UTCJul 9, 09:10 UTC55m
2026-07-09 EAI73N - Jul 9, 06:30 UTCJul 9, 07:25 UTC55m
2026-07-08 EAI29GA - Jul 8, 21:05 UTCJul 8, 21:50 UTC45m
2026-07-08 EAI38JL ORK → GLA Jul 8, 19:00 UTCJul 8, 20:20 UTC1h 20m
2026-07-08 EAI43S - Jul 8, 16:45 UTCJul 8, 18:05 UTC1h 20m
2026-07-08 EAI28QB DUB → GLA Jul 8, 15:05 UTCJul 8, 15:55 UTC50m
2026-07-08 EAI2DM GLA → DUB Jul 8, 12:45 UTCJul 8, 13:35 UTC50m
2026-07-08 EAI26PK DUB → GLA Jul 8, 11:10 UTCJul 8, 12:00 UTC50m
2026-07-08 EAI34N - Jul 8, 08:55 UTCJul 8, 10:10 UTC1h 15m
2026-07-08 EAI42A - Jul 8, 07:00 UTCJul 8, 08:05 UTC1h 5m
2026-07-07 EAI89DF - Jul 7, 19:25 UTCJul 7, 20:20 UTC55m
2026-07-07 EAI17C ORK → BRS Jul 7, 17:50 UTCJul 7, 18:50 UTC1h 0m
2026-07-07 EAI18K BRS → ORK Jul 7, 15:55 UTCJul 7, 17:00 UTC1h 5m
2026-07-07 EAI86W DUB → BRS Jul 7, 14:05 UTCJul 7, 15:05 UTC1h 0m
2026-07-07 EAI53BS EDI → DUB Jul 7, 11:30 UTCJul 7, 12:30 UTC1h 0m
2026-07-07 EAI52NE DUB → EDI Jul 7, 09:35 UTCJul 7, 10:35 UTC1h 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-HDK page for operator, model, and routing details .

Mode-S 4CAD51 frequently asked

What is Mode-S code 4CAD51?
4CAD51 is an ICAO 24-bit transponder address. Allocated to Ireland. Assigned to EI-HDK.
Where is Mode-S 4CAD51 registered?
Mode-S code 4CAD51 is allocated to Ireland (IE). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 4CAD51 broadcasting right now?
No active broadcast right now. Last signal was 8h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 4CAD51, octal 23126521, decimal 5,025,105.
What flights does 4CAD51 operate?
Mode-S 4CAD51 has broadcast 20 distinct callsigns, including EAI09U, EAI8C, EAI73N, EAI93D, EAI69M.