Apparatus

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sensors Mode-S transponder

A4CA20

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N4078P · ROBINSON R-22 Mariner · operated by HAWAII PACIFIC AVIATION INC

Hex
A4CA20
Octal
51145040
Decimal
10,799,648
Country
US
Tail
N4078P
Type
R22
No current signal · last broadcast 1d ago
Flights observed
7
Distinct callsigns
1
Country
US
Last broadcast
1d ago

Last known position

Most recent position reported by Mode-S A4CA20.

Country allocation

The ICAO 24-bit address A4CA20 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 1 distinct

Callsign Airline Flights Last seen
N4078P - 7 2026-04-13

Recent flights last 7

DateFlightRouteTakeoffLandingDuration
2026-04-13 N4078P KOA → KOA Apr 13, 21:20 UTCApr 13, 22:00 UTC40m
2026-04-13 N4078P KOA → KOA Apr 13, 19:50 UTCApr 13, 20:40 UTC50m
2026-04-13 N4078P KOA → KOA Apr 13, 19:35 UTCApr 13, 19:45 UTC10m
2026-04-13 N4078P KOA → KOA Apr 13, 00:20 UTCApr 13, 00:55 UTC35m
2026-04-13 N4078P KOA → KOA Apr 13, 00:05 UTCApr 13, 00:55 UTC50m
2026-04-12 N4078P KOA → KOA Apr 12, 19:50 UTCApr 12, 20:15 UTC25m
2026-04-12 N4078P KOA → KOA Apr 12, 17:50 UTCApr 12, 18:45 UTC55m

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 N4078P page for operator, model, and routing details .

Mode-S A4CA20 frequently asked

What is Mode-S code A4CA20?
A4CA20 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N4078P.
Where is Mode-S A4CA20 registered?
Mode-S code A4CA20 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 A4CA20 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 A4CA20, octal 51145040, decimal 10,799,648.
What flights does A4CA20 operate?
Mode-S A4CA20 has broadcast 1 distinct callsign, including N4078P.