sensors Mode-S transponder

A3FFAF

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N357K · LEARJET 45 · operated by KIEWIT ENGINEERING GROUP INC

Hex
A3FFAF
Octal
50777657
Decimal
10,747,823
Country
US
Tail
N357K
Type
LJ45
No current signal · last broadcast 1d ago
Flights observed
1
Distinct callsigns
1
Country
US
Last broadcast
1d ago

Last known position

Most recent position reported by Mode-S A3FFAF.

Country allocation

The ICAO 24-bit address A3FFAF 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
DZR357 - 1 2026-04-13

Recent flights last 1

DateFlightRouteTakeoffLandingDuration
2026-04-13 DZR357 CBF → MDW Apr 13, 20:20 UTCApr 13, 21:25 UTC1h 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 N357K page for operator, model, and routing details .

Mode-S A3FFAF frequently asked

What is Mode-S code A3FFAF?
A3FFAF is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N357K.
Where is Mode-S A3FFAF registered?
Mode-S code A3FFAF 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 A3FFAF 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 A3FFAF, octal 50777657, decimal 10,747,823.
What flights does A3FFAF operate?
Mode-S A3FFAF has broadcast 1 distinct callsign, including DZR357.