sensors Mode-S transponder

4CAC66

ICAO 24-bit transponder address · allocated to Ireland

Currently assigned to EI-AZE · BOEING 737-800

Hex
4CAC66
Octal
23126146
Decimal
5,024,870
Country
IE
Tail
EI-AZE
Type
B738
No current signal · last broadcast 19h ago
Flights observed
3
Distinct callsigns
2
Country
IE
Last broadcast
19h ago

Last known position

Most recent position reported by Mode-S 4CAC66.

Country allocation

The ICAO 24-bit address 4CAC66 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 2 distinct

Callsign Airline Flights Last seen
ABR403 - 2 2026-04-13
ABR402 ASL Airlines Ireland 1 2026-04-14

Recent flights last 3

DateFlightRouteTakeoffLandingDuration
2026-04-14 ABR402 MAD → LEJ Apr 14, 05:15 UTCApr 14, 07:00 UTC1h 45m
2026-04-13 ABR403 - Apr 13, 00:20 UTCApr 13, 01:45 UTC1h 25m
2026-04-12 ABR403 - Apr 12, 23:55 UTCApr 13, 01:45 UTC1h 50m

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-AZE page for operator, model, and routing details .

Mode-S 4CAC66 frequently asked

What is Mode-S code 4CAC66?
4CAC66 is an ICAO 24-bit transponder address. Allocated to Ireland. Assigned to EI-AZE.
Where is Mode-S 4CAC66 registered?
Mode-S code 4CAC66 is allocated to Ireland (IE). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 4CAC66 broadcasting right now?
No active broadcast right now. Last signal was 19h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 4CAC66, octal 23126146, decimal 5,024,870.
What flights does 4CAC66 operate?
Mode-S 4CAC66 has broadcast 2 distinct callsigns, including ABR403, ABR402.