sensors Mode-S transponder

39ACA4

ICAO 24-bit transponder address · allocated to France

Currently assigned to F-HLFE · CESSNA 525B Citation CJ3

Hex
39ACA4
Octal
16326244
Decimal
3,779,748
Country
FR
Tail
F-HLFE
Type
C25B
No current signal · last broadcast 1d ago
Flights observed
2
Distinct callsigns
1
Country
FR
Last broadcast
1d ago

Last known position

Most recent position reported by Mode-S 39ACA4.

Country allocation

The ICAO 24-bit address 39ACA4 falls within the block assigned to France (FR) by ICAO Annex 10, Volume III. Every aircraft registered in France 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
FHLFE - 2 2026-04-13

Recent flights last 2

DateFlightRouteTakeoffLandingDuration
2026-04-13 FHLFE - Apr 13, 11:55 UTCApr 13, 12:10 UTC15m
2026-04-13 FHLFE - Apr 13, 10:45 UTCApr 13, 12:10 UTC1h 25m

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 F-HLFE page for operator, model, and routing details .

Mode-S 39ACA4 frequently asked

What is Mode-S code 39ACA4?
39ACA4 is an ICAO 24-bit transponder address. Allocated to France. Assigned to F-HLFE.
Where is Mode-S 39ACA4 registered?
Mode-S code 39ACA4 is allocated to France (FR). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 39ACA4 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 39ACA4, octal 16326244, decimal 3,779,748.
What flights does 39ACA4 operate?
Mode-S 39ACA4 has broadcast 1 distinct callsign, including FHLFE.