Date:	Thursday 10 October 2024
Time:	07:40 UTC
Type:	Flight Design CTSW
Owner/operator:	Private
Registration:	G-CFFJ
MSN:	8391
Fatalities:	Fatalities: 0 / Occupants: 1
Other fatalities:	0
Aircraft damage:	Destroyed
Category:	Accident
Location:	Carlisle (Lake District) Airport, Irthington, Carlisle, Cumbria -   United Kingdom
Phase:	Take off
Nature:	Private
Departure airport:	Carlisle Lake District Airport (CAX/EGNC)
Destination airport:
Investigating agency:	AAIB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
A Flight Design CTSW, G-CFFJ, suffered a loss of control during takeoff from Carlisle Airport, Cumbria. The aircraft was deemed written off (damaged beyond repair).

The pilot intended to make an early local flight in fine weather. He completed the pre-flight checks, including latching the left cabin door closed as it had been open when he entered the cockpit. He started the engine and taxied to holding point A for Runway 19, where he completed pre-departure checks. As the flight was being made before the airport’s normal opening time, the pilot made blind radio transmissions on the A/G frequency.

He called stating that he was entering Runway 19 for a southerly departure and this call was acknowledged by the driver of an airport vehicle that was being used for runway checks. The pilot applied full power, released the brakes and the aircraft accelerated normally.

During the takeoff ground roll, the aircraft ran across a joint in the paved runway surface and the pilot described hearing a rattle from the left cabin door. He glanced down to his left and thought that he may haveseen a gap between the bottom of the door and the door aperture, however the aircraft was now at flying speed and he rotated into a climbing attitude.

The pilot estimated that the left cabin door suddenly opened whilst the aircraft was passing 50-100 ft in the climbout. He stated “I was hit with tremendous turbulence in the cockpit, with maps and papers swirling around”. He was also concerned about visible flexing to the large cabin door, and the possibility that it might detach and strike the tailplane. He tried to close the cabin door with both hands, whilst holding the control column between his knees, but was unsuccessful and decided to reduce engine power and try again.

During the second attempt to close the door he managed to move the door to its closed position but was unable to move the door locking lever fully forward and during this attempt the aircraft stalled, with the right wing dropping.

The pilot pitched the aircraft nose down and applied full power, however there was insufficient height for a recovery and the aircraft struck an open area of soft ground outside the airport perimeter fence. The pilot received serious facial injuries and fractures to his right foot. No fire occurred and a combination of airport staff and local emergency response vehicles quickly attended the accident site

Aircraft examination
The aircraft wreckage was examined by the AAIB following the accident, and significant wear was observed to the door latching pins at the point where the pin bears against the door aperture’s composite frame when the door is in the closed position. This prompted a survey of three other similar CTSW and CTLS1 aircraft, which were found to also exhibit similar wear of the door latch pins. The force required to move the door latch lever, from a closed (but with the lever out of the detent) to open position, was measured and found to be in the range 20-30 N. This represented a positive effort to unlatch the door, and the owners of the three aircraft examined stated that none had suffered from uncommanded door opening when the door was latched closed with the lever in the detent position.

AAIB Analysis
The cause of the left cabin door opening during the flight was likely due to it being not fully latched closed, with the latch handle in the closed detent, prior to takeoff. Airframe vibration during the takeoff roll, including that experienced when rolling over joints in the runway’s paved surface, probably caused the unlatched lever to migrate sufficiently to allow the door latching pins to disengage from their mating holes in the door aperture frame, allowing the door to open. Once unlatched, opening of the cabin door was assisted by the door gas spring and air loads, causing the rapid door opening experienced by the pilot. The wear observed to the door latching pins was found to be common to other similar aircraft in the fleet and is not considered contributory to the uncommanded door opening.

The unexpected opening of the cabin door created a hazardous situation for the pilot whilst the aircraft was close to the ground, shortly after becoming airborne. His efforts to control the aircraft whilst attempting to close the door were unsuccessful, leading to the aircraft stalling at a height that was insufficient for him to recover

Damage Sustained to airframe
Per the AAIB Report "Aircraft destroyed"

1. AAIB Final Report: https://assets.publishing.service.gov.uk/media/67cffedff5aaff610c9f5ee4/Flight_Design_CTSW_G-CFFJ_03-25.pdf
2. https://airport-data.com/aircraft/G-CFFJ.html
3. AirNav Radar: https://www.airnavradar.com/data/registration/G-CFFJ/2236496814
4. Flight Radar 24: https://www.flightradar24.com/data/aircraft/g-cffj
5. https://planefinder.net/data/aircraft/G-CFFJ
6. https://en.wikipedia.org/wiki/Carlisle_Lake_District_Airport

Built 2008, and only ever UK-registered from new. First UK registered as G-CFFJ on 15 May 2008 to a private owner in Newark, Nottinghamshire. Registration cancelled 28 February 2022 as \\\"owner deceased\\\". Re-registered to the 2nd owner on 28 February 2022. Total amount of hours accumulated on the airframe: 787 at 12 August 2024. Registration still current as at March 2025, although the C of A/Permit to Fly was suspended following the incident at Carlisle on 10 October 2024.

Photo: AAIB

Flight Design CTSW G-CFFJ at Northrepps Airfield, Norfolk 12 July 2020 Flight Design CTSW G-CFFJ at Northrepps Airfield, Norfolk 24 March 2019

Date/time	Contributor	Updates
13-Mar-2025 15:26	Dr. John Smith	Added
13-Mar-2025 15:28	ASN	Updated [Narrative, Accident report, ]
13-Mar-2025 15:30	ASN	Updated [Photo, ]