sensors Mode-S transponder

3991E5

ICAO 24-bit transponder address · allocated to France

Currently assigned to F-HEPF · AIRBUS A-320

Hex
3991E5
Octal
16310745
Decimal
3,772,901
Country
FR
Tail
F-HEPF
Type
A320
No current signal · last broadcast 37m ago
Flights observed
5
Distinct callsigns
6
Country
FR
Last broadcast
37m ago

Last known position

Most recent position reported by Mode-S 3991E5.

Country allocation

The ICAO 24-bit address 3991E5 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 6 distinct

Callsign Airline Flights Last seen
AFR99GT Air France 1 2026-05-22
AFR97RN Air France 1 2026-05-22
AFR64PU Air France 1 2026-05-22
AFR363S - 1 2026-05-21
AFR361V Air France 1 2026-05-21
AFR1896 Air France 1 2026-05-22

Recent flights last 6

DateFlightRouteTakeoffLandingDuration
2026-05-22 AFR99GT BER → CDG May 22, 17:35 UTCMay 22, 18:50 UTC1h 15m
2026-05-22 AFR64PU CDG → BER May 22, 15:15 UTCMay 22, 16:30 UTC1h 15m
2026-05-22 AFR97RN CMN → CDG May 22, 09:40 UTCMay 22, 12:05 UTC2h 25m
2026-05-22 AFR1896 CDG → CMN May 22, 05:20 UTCMay 22, 07:50 UTC2h 30m
2026-05-21 AFR361V CMN → CDG May 21, 16:20 UTCMay 21, 18:05 UTC1h 45m
2026-05-21 AFR363S - May 21, 11:00 UTCMay 21, 14:25 UTC3h 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-HEPF page for operator, model, and routing details .

Mode-S 3991E5 frequently asked

What is Mode-S code 3991E5?
3991E5 is an ICAO 24-bit transponder address. Allocated to France. Assigned to F-HEPF.
Where is Mode-S 3991E5 registered?
Mode-S code 3991E5 is allocated to France (FR). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 3991E5 broadcasting right now?
No active broadcast right now. Last signal was 37m ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 3991E5, octal 16310745, decimal 3,772,901.
What flights does 3991E5 operate?
Mode-S 3991E5 has broadcast 6 distinct callsigns, including AFR99GT, AFR97RN, AFR64PU, AFR363S, AFR361V.