Apparatus

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sensors Mode-S transponder

A1A4C9

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N205CA · CESSNA 402 Businessliner · operated by HYANNIS AIR SERVICE INC DBA, CAPE AIR

Hex
A1A4C9
Octal
50322311
Decimal
10,593,481
Country
US
Tail
N205CA
Type
C402
No current signal · last broadcast 1d ago
Flights observed
9
Distinct callsigns
2
Country
US
Last broadcast
1d ago

Last known position

Most recent position reported by Mode-S A1A4C9.

Country allocation

The ICAO 24-bit address A1A4C9 falls within the block assigned to United States (US) by ICAO Annex 10, Volume III. Every aircraft registered in United States 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
KAP65 Cape Air 6 2026-04-13
KAP55 Cape Air 3 2026-04-12

Recent flights last 9

DateFlightRouteTakeoffLandingDuration
2026-04-13 KAP65 BOS → MVY Apr 13, 20:45 UTCApr 13, 21:05 UTC20m
2026-04-13 KAP65 BOS → MVY Apr 13, 19:35 UTCApr 13, 19:45 UTC10m
2026-04-13 KAP65 BOS → MVY Apr 13, 18:05 UTCApr 13, 18:25 UTC20m
2026-04-13 KAP65 BOS → MVY Apr 13, 16:55 UTCApr 13, 17:10 UTC15m
2026-04-13 KAP65 BOS → MVY Apr 13, 13:35 UTCApr 13, 13:50 UTC15m
2026-04-13 KAP65 BOS → MVY Apr 13, 12:20 UTCApr 13, 12:35 UTC15m
2026-04-12 KAP55 BOS → RUT Apr 12, 19:55 UTCApr 12, 20:15 UTC20m
2026-04-12 KAP55 BOS → RUT Apr 12, 18:35 UTCApr 12, 18:50 UTC15m
2026-04-12 KAP55 BOS → RUT Apr 12, 17:15 UTCApr 12, 17:30 UTC15m

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 N205CA page for operator, model, and routing details .

Mode-S A1A4C9 frequently asked

What is Mode-S code A1A4C9?
A1A4C9 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N205CA.
Where is Mode-S A1A4C9 registered?
Mode-S code A1A4C9 is allocated to United States (US). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is A1A4C9 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 A1A4C9, octal 50322311, decimal 10,593,481.
What flights does A1A4C9 operate?
Mode-S A1A4C9 has broadcast 2 distinct callsigns, including KAP65, KAP55.