sensors Mode-S transponder

406DF4

ICAO 24-bit transponder address · allocated to United Kingdom

Currently assigned to G-HIAL · DE HAVILLAND DHC-6 Twin Otter

Hex
406DF4
Octal
20066764
Decimal
4,222,452
Country
GB
Tail
G-HIAL
Type
DHC6
No current signal · last broadcast 21h ago
Flights observed
10
Distinct callsigns
1
Country
GB
Last broadcast
21h ago

Last known position

Most recent position reported by Mode-S 406DF4.

Country allocation

The ICAO 24-bit address 406DF4 falls within the block assigned to United Kingdom (GB) by ICAO Annex 10, Volume III. Every aircraft registered in United Kingdom 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
GHIAL - 10 2026-04-14

Recent flights last 10

DateFlightRouteTakeoffLandingDuration
2026-04-14 GHIAL - Apr 14, 09:20 UTCApr 14, 09:40 UTC20m
2026-04-14 GHIAL - Apr 14, 08:25 UTCApr 14, 08:40 UTC15m
2026-04-14 GHIAL - Apr 14, 07:05 UTCApr 14, 07:10 UTC5m
2026-04-13 GHIAL - Apr 13, 17:15 UTCApr 13, 17:45 UTC30m
2026-04-13 GHIAL - Apr 13, 15:55 UTCApr 13, 16:15 UTC20m
2026-04-13 GHIAL - Apr 13, 14:15 UTCApr 13, 14:40 UTC25m
2026-04-13 GHIAL - Apr 13, 12:20 UTCApr 13, 12:35 UTC15m
2026-04-13 GHIAL - Apr 13, 12:05 UTCApr 13, 12:15 UTC10m
2026-04-13 GHIAL - Apr 13, 09:40 UTCApr 13, 10:00 UTC20m
2026-04-13 GHIAL - Apr 13, 08:20 UTCApr 13, 08:35 UTC15m

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 G-HIAL page for operator, model, and routing details .

Mode-S 406DF4 frequently asked

What is Mode-S code 406DF4?
406DF4 is an ICAO 24-bit transponder address. Allocated to United Kingdom. Assigned to G-HIAL.
Where is Mode-S 406DF4 registered?
Mode-S code 406DF4 is allocated to United Kingdom (GB). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is 406DF4 broadcasting right now?
No active broadcast right now. Last signal was 21h ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 406DF4, octal 20066764, decimal 4,222,452.
What flights does 406DF4 operate?
Mode-S 406DF4 has broadcast 1 distinct callsign, including GHIAL.