sensors Mode-S transponder

AC9AA2

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N911CP · HUGHES 500 · operated by ST LOUIS COUNTY POLICE DEPARTMENT

Hex
AC9AA2
Octal
53115242
Decimal
11,311,778
Country
US
Tail
N911CP
Type
H500
No current signal · last broadcast 1d ago
Flights observed
3
Distinct callsigns
1
Country
US
Last broadcast
1d ago

Last known position

Most recent position reported by Mode-S AC9AA2.

Country allocation

The ICAO 24-bit address AC9AA2 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
N911CP - 3 2026-04-13

Recent flights last 3

DateFlightRouteTakeoffLandingDuration
2026-04-13 N911CP - Apr 13, 20:10 UTCApr 13, 21:55 UTC1h 45m
2026-04-13 N911CP - Apr 13, 16:15 UTCApr 13, 17:40 UTC1h 25m
2026-04-13 N911CP - Apr 13, 15:50 UTCApr 13, 16:15 UTC25m

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 N911CP page for operator, model, and routing details .

Mode-S AC9AA2 frequently asked

What is Mode-S code AC9AA2?
AC9AA2 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N911CP.
Where is Mode-S AC9AA2 registered?
Mode-S code AC9AA2 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 AC9AA2 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 AC9AA2, octal 53115242, decimal 11,311,778.
What flights does AC9AA2 operate?
Mode-S AC9AA2 has broadcast 1 distinct callsign, including N911CP.