sensors Mode-S transponder

4CA961

ICAO 24-bit transponder address · allocated to Ireland

Currently assigned to EI-RZC · BOEING 737 MAX 8

Hex
4CA961
Octal
23124541
Decimal
5,024,097
Country
IE
Tail
EI-RZC
Type
B38M
No current signal · last broadcast 1d ago
Flights observed
6
Distinct callsigns
1
Country
IE
Last broadcast
1d ago

Last known position

Most recent position reported by Mode-S 4CA961.

Country allocation

The ICAO 24-bit address 4CA961 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 1 distinct

Callsign Airline Flights Last seen
NOS1350 Neos 6 2026-04-13

Recent flights last 6

DateFlightRouteTakeoffLandingDuration
2026-04-13 NOS1350 LPA → MXP Apr 13, 16:15 UTCApr 13, 17:10 UTC55m
2026-04-13 NOS1350 LPA → MXP Apr 13, 15:50 UTCApr 13, 17:10 UTC1h 20m
2026-04-13 NOS1350 LPA → MXP Apr 13, 13:25 UTCApr 13, 16:15 UTC2h 50m
2026-04-13 NOS1350 LPA → MXP Apr 13, 08:20 UTCApr 13, 09:30 UTC1h 10m
2026-04-13 NOS1350 LPA → MXP Apr 13, 07:55 UTCApr 13, 09:30 UTC1h 35m
2026-04-13 NOS1350 LPA → MXP Apr 13, 06:10 UTCApr 13, 08:15 UTC2h 5m

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

Mode-S 4CA961 frequently asked

What is Mode-S code 4CA961?
4CA961 is an ICAO 24-bit transponder address. Allocated to Ireland. Assigned to EI-RZC.
Where is Mode-S 4CA961 registered?
Mode-S code 4CA961 is allocated to Ireland (IE). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 4CA961 broadcasting right now?
No active broadcast right now. Last signal was 1d ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 4CA961, octal 23124541, decimal 5,024,097.
What flights does 4CA961 operate?
Mode-S 4CA961 has broadcast 1 distinct callsign, including NOS1350.