Date:	Friday 8 June 2018
Time:	15:02 UTC
Type:	Schleicher ASK 21
Owner/operator:	London Gliding Club (Proprietary) Ltd
Registration:	G-CFYF
MSN:	21470
Fatalities:	Fatalities: 0 / Occupants: 2
Aircraft damage:	Minor
Category:	Accident
Location:	Dunstable Downs Airfield, Icknield Way, Whipsnade, Dunstable -   United Kingdom
Phase:	Initial climb
Nature:	Training
Departure airport:	Dunstable Downs, Icknield Way, Whipsnade, Dunstable, Bedfordshire
Destination airport:	Dunstable Downs, Icknield Way, Whipsnade, Dunstable, Bedfordshire
Investigating agency:	AAIB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
AAIB investigation to Pierre Robin DR400/180R Remorqueur, G-LGCC and Schleicher ASK 21, G-CFYF: Mid-air collision, Dunstable Airfield, Bedfordshire, 8 June 2018.

During the recovery to Dunstable Downs Airfield (DDA) after conducting a successful aero-tow launch, the pilot of the tug aircraft, G-LGCC, became aware of a glider ahead of him at close range. The pilot bunted to pass underneath the glider but had insufficient time to avoid a collision. The top of G-LGCC’s fin struck the outboard leading edge of the glider’s right wing. Despite suffering major damage, both aircraft remained controllable and landed without further incident.

G-CFYF, a 2-seater glider also operated by the gliding club, was conducting a training flight for the front-seat occupant. After winch launching to the north-east the glider followed a thermal southward. On reaching the southern airspace boundary the pilots elected to reposition to the north over Dunstable Downs prior to joining the circuit for landing.

Immediately prior to the accident the glider was tracking north easterly at 50 knots and approximately 900 ft agl. Neither occupant saw the tug aircraft and the first they knew of the collision was a loud bang
accompanied by the glider yawing violently to the right. The instructor in the rear-seat took control of G-CFYF to make an initial damage assessment.

Looking to the right he could see significant disruption to the wing structure, but the wingtip angle looked normal, implying that the spar was intact. The glider was still flying and responding normally to control inputs. With members of the public below and the aircraft under control, the instructor elected to continue recovering to the field rather than risk a low-level abandonment. The glider landed without further incident.

=Safety actions=
To reduce the risk of mid-air collisions between aero-tugs and gliders, the gliding club decided to:
● Publicise and enforce the policy of using landing lights on their tug aircraft during normal towing operations.
● Resolve the issue of radio interference generated by LED landing lights on the Club’s aero-tow aircraft.
● Review the policy on FLARM fitment for Club owned aircraft.
● Investigate the possibility of fitting extended life batteries to all Club aircraft with the aim of enabling radio use for all flights and supporting a growth path for wider use of electronic conspicuity systems

=Damage to airframe=
Per the above AAIB report "Full depth gash in outboard section of right wing"

1. AAIB Report into accident between Robin G-LGCC and Schleicher ASK 21 G-CFYF on 8 June 2018: https://assets.publishing.service.gov.uk/media/5f48bdb58fa8f57fbbf80d5b/Pierre_Robin_DR400_180R_G-LGCC_Schleicher_ASK_21_G-CFYF_11-18.pdf
2. BFU Germany Report BFU18-1184-DX: https://www.bfu-web.de/DE/Publikationen/Bulletins/2018/Bulletin2018-08.pdf?__blob=publicationFile&v=2
3. https://www.planelogger.com/Aircraft/Registration/G-CFYF/947022
4. http://www.rcawsey.co.uk/ask212.htm
5. https://www.londonglidingclub.co.uk/about-us/our-airfield
6. https://en.wikipedia.org/wiki/London_Gliding_Club

Schleicher K21 G-CFYF was built in 1990, and initially registered on the British Gliding Association register as BGA 3625. It became G-CFYF from 22 May 2008

Date/time	Contributor	Updates
03-Apr-2024 14:43	Dr. John Smith	Added
03-Apr-2024 14:46	ASN	Updated [Embed code, Accident report]