Apparatus

Try JFK, AAL1290, BAW, or N225AN.

sensors Mode-S transponder

400399

ICAO 24-bit transponder address · allocated to United Kingdom

Currently assigned to VQ-THM · ATR-42-500

Hex
400399
Octal
20001631
Decimal
4,195,225
Country
GB
Tail
VQ-THM
Type
AT45
No current signal · last broadcast 9d ago
Flights observed
121
Distinct callsigns
20
Country
GB
Last broadcast
9d ago

Last known position

Most recent position reported by Mode-S 400399.

Country allocation

The ICAO 24-bit address 400399 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 20 distinct

Callsign Airline Flights Last seen
IWY411 Interisland Airways Limited 12 2026-06-04
IWY410 Interisland Airways Limited 12 2026-07-10
IWY510 - 9 2026-07-09
IWY509 Interisland Airways Limited 9 2026-07-10
IWY764 - 8 2026-07-08
IWY512 - 8 2026-07-09
IWY703 - 7 2026-07-08
IWY511 - 7 2026-07-09
IWY508 Interisland Airways Limited 6 2026-05-17
IWY743 - 4 2026-07-07
IWY742 - 4 2026-07-06
IWY513 Interisland Airways Limited 4 2026-05-15
IWY644 Interisland Airways Limited 3 2026-07-10
IWY793 - 2 2026-07-06
IWY792 - 2 2026-07-06
IWY766 - 2 2026-07-04
IWY748 - 2 2026-07-03
IWY643 - 2 2026-07-09
IWY788 - 1 2026-07-03
IWY787 Interisland Airways Limited 1 2026-07-04

Recent flights last 50

DateFlightRouteTakeoffLandingDuration
2026-07-10 IWY410 EIS → SDQ Jul 10, 16:45 UTCJul 10, 17:10 UTC25m
2026-07-10 IWY509 SJU → EIS Jul 10, 14:25 UTCJul 10, 14:40 UTC15m
2026-07-10 IWY644 SKB → SJU Jul 10, 12:50 UTCJul 10, 13:15 UTC25m
2026-07-09 IWY643 - Jul 9, 21:30 UTCJul 9, 21:55 UTC25m
2026-07-09 IWY512 - Jul 9, 19:35 UTCJul 9, 19:55 UTC20m
2026-07-09 IWY511 - Jul 9, 17:20 UTCJul 9, 17:35 UTC15m
2026-07-09 IWY510 - Jul 9, 15:35 UTCJul 9, 15:50 UTC15m
2026-07-08 IWY556 - Jul 8, 15:55 UTCJul 8, 16:35 UTC40m
2026-07-08 IWY703 - Jul 8, 13:15 UTCJul 8, 13:45 UTC30m
2026-07-08 IWY703 - Jul 8, 12:05 UTCJul 8, 12:20 UTC15m
2026-07-08 IWY764 - Jul 8, 00:00 UTCJul 8, 00:10 UTC10m
2026-07-07 IWY764 - Jul 7, 22:55 UTCJul 7, 23:15 UTC20m
2026-07-07 IWY719 GND → BGI Jul 7, 18:00 UTCJul 7, 18:30 UTC30m
2026-07-07 IWY718 SVD → GND Jul 7, 16:45 UTCJul 7, 17:15 UTC30m
2026-07-07 IWY703 - Jul 7, 15:20 UTCJul 7, 15:50 UTC30m
2026-07-07 IWY703 - Jul 7, 14:20 UTCJul 7, 14:30 UTC10m
2026-07-07 IWY764 - Jul 7, 01:50 UTCJul 7, 02:20 UTC30m
2026-07-07 IWY743 - Jul 7, 00:10 UTCJul 7, 00:30 UTC20m
2026-07-06 IWY742 - Jul 6, 22:30 UTCJul 6, 22:45 UTC15m
2026-07-06 IWY793 - Jul 6, 21:00 UTCJul 6, 21:20 UTC20m
2026-07-06 IWY792 - Jul 6, 17:50 UTCJul 6, 18:15 UTC25m
2026-07-06 IWY703 - Jul 6, 16:10 UTCJul 6, 16:35 UTC25m
2026-07-06 IWY764 - Jul 6, 15:15 UTCJul 6, 15:25 UTC10m
2026-07-06 IWY764 - Jul 6, 02:35 UTCJul 6, 02:50 UTC15m
2026-07-06 IWY764 - Jul 6, 01:35 UTCJul 6, 01:55 UTC20m
2026-07-05 IWY743 - Jul 5, 23:55 UTCJul 6, 00:25 UTC30m
2026-07-05 IWY742 - Jul 5, 22:30 UTCJul 5, 22:55 UTC25m
2026-07-05 IWY705 - Jul 5, 15:10 UTCJul 5, 15:35 UTC25m
2026-07-04 IWY766 - Jul 4, 23:45 UTCJul 5, 00:10 UTC25m
2026-07-04 IWY743 - Jul 4, 21:50 UTCJul 4, 22:30 UTC40m
2026-07-04 IWY742 - Jul 4, 19:10 UTCJul 4, 19:30 UTC20m
2026-07-04 IWY717 SVD → BGI Jul 4, 17:15 UTCJul 4, 17:35 UTC20m
2026-07-04 IWY716 BGI → SVD Jul 4, 15:45 UTCJul 4, 16:10 UTC25m
2026-07-04 IWY787 BGI → GEO Jul 4, 14:35 UTCJul 4, 14:50 UTC15m
2026-07-03 IWY788 - Jul 3, 23:40 UTCJul 4, 00:00 UTC20m
2026-07-03 IWY749 - Jul 3, 22:00 UTCJul 3, 22:30 UTC30m
2026-07-03 IWY748 - Jul 3, 21:05 UTCJul 3, 21:15 UTC10m
2026-07-03 IWY748 - Jul 3, 19:55 UTCJul 3, 20:15 UTC20m
2026-07-03 IWY793 - Jul 3, 18:25 UTCJul 3, 18:50 UTC25m
2026-07-03 IWY792 - Jul 3, 15:50 UTCJul 3, 16:25 UTC35m
2026-07-03 IWY707 - Jul 3, 13:30 UTCJul 3, 14:05 UTC35m
2026-06-29 IWY766 - Jun 29, 22:19 UTCJun 29, 22:44 UTC25m
2026-06-29 IWY557 - Jun 29, 20:09 UTCJun 29, 20:44 UTC35m
2026-06-29 IWY554 BGI → EIS Jun 29, 16:10 UTCJun 29, 16:29 UTC20m
2026-06-29 IWY703 GND → SVD Jun 29, 15:00 UTCJun 29, 15:24 UTC25m
2026-06-29 IWY764 - Jun 29, 01:14 UTCJun 29, 01:29 UTC15m
2026-06-29 IWY764 - Jun 29, 00:14 UTCJun 29, 00:34 UTC20m
2026-06-28 IWY743 - Jun 28, 22:34 UTCJun 28, 22:59 UTC25m
2026-06-28 IWY742 - Jun 28, 21:24 UTCJun 28, 21:45 UTC20m
2026-06-28 IWY715 - Jun 28, 20:14 UTCJun 28, 20:29 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 VQ-THM page for operator, model, and routing details .

Mode-S 400399 frequently asked

What is Mode-S code 400399?
400399 is an ICAO 24-bit transponder address. Allocated to United Kingdom. Assigned to VQ-THM.
Where is Mode-S 400399 registered?
Mode-S code 400399 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 400399 broadcasting right now?
No active broadcast right now. Last signal was 9d ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex 400399, octal 20001631, decimal 4,195,225.
What flights does 400399 operate?
Mode-S 400399 has broadcast 20 distinct callsigns, including IWY411, IWY410, IWY510, IWY509, IWY764.