sensors Mode-S transponder

AC0921

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N875CF · operated by PARAGON AIRPLANE LEASING CO

Hex
AC0921
Octal
53004441
Decimal
11,274,529
Country
US
Tail
N875CF
Type
P28A
Broadcasting now · callsign N875CF · 2,450 ft
Flights observed
5
Distinct callsigns
1
Country
US
Last broadcast
1d ago

Current position

AC0921 is currently broadcasting. Map zoomed to live position.

Country allocation

The ICAO 24-bit address AC0921 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
N875CF - 5 2026-04-13

Recent flights last 5

DateFlightRouteTakeoffLandingDuration
2026-04-13 N875CF - Apr 13, 18:25 UTCApr 13, 19:50 UTC1h 25m
2026-04-13 N875CF - Apr 13, 16:35 UTCApr 13, 17:40 UTC1h 5m
2026-04-13 N875CF FMY → FMY Apr 13, 14:35 UTCApr 13, 15:40 UTC1h 5m
2026-04-13 N875CF - Apr 13, 10:50 UTCApr 13, 11:55 UTC1h 5m
2026-04-12 N875CF - Apr 12, 17:15 UTCApr 12, 17:50 UTC35m

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 N875CF page for operator, model, and routing details .

Mode-S AC0921 frequently asked

What is Mode-S code AC0921?
AC0921 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N875CF.
Where is Mode-S AC0921 registered?
Mode-S code AC0921 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 AC0921 broadcasting right now?
Yes. Mode-S AC0921 is currently airborne.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex AC0921, octal 53004441, decimal 11,274,529.
What flights does AC0921 operate?
Mode-S AC0921 has broadcast 1 distinct callsign, including N875CF.