ASN Wikibase Occurrence # 29627
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| Date: | Friday 6 May 1966 |
| Time: | day |
| Type: | Slingsby T.50 Skylark 4 |
| Owner/operator: | Yorkshire Gliding Club |
| Registration: | BGA 1069 |
| MSN: | 1349 |
| Fatalities: | Fatalities: 1 / Occupants: 1 |
| Aircraft damage: | Destroyed |
| Location: | near Easingwold, Yorkshire -
 United Kingdom
|
| Phase: | En route |
| Nature: | Private |
| Departure airport: | Sutton Bank, North Yorkshire |
| Confidence Rating: |  Information is only available from news, social media or unofficial sources |
On 6th May 1966 the pilot of this glider was carrying out a local flight when the glider entered a cumulo-nimbus cloud which was obscured by a continuous sheet of medium cloud. The glider sustained a lightning strike which either melted or vaporised the aileron cables and caused the wing centre section to disintegrate. The pilot fell out of the glider and was wearing a parachute but he did not deploy it and was killed. Pilot - Mr Peter Hill, killed.
According to the official accident report (No. 275), which was published in "Sailplane & Gliding Magazine" (June-July 1967 issue):
"THE Board of Trade has now published the report on the Accident Investigation Branch enquiry into the accident to Slingsby Skylark 4, BGA No. 1069, which occurred near Easingwold, Yorkshire, on 6th May, 1966, in which Peter Hill was killed. Copies of the report may be obtained from H.M. Stationery Office, price 3 shillings.
The summary of the accident states:-
"During a local soaring flight the glider entered a cumulonimbus cloud which was partially obscured by a continuous sheet of medium cloud; the aircraft sustained a medium to severe lightning strike which melted or possibly vapourised the aileron cables and caused the wing centre-plane to disintegrate.
The pilot, who was wearing a parachute, fell clear of the wrecked glider but for reasons which have not been established did not deploy his parachute and was killed."
The report shows quite clearly that the flight was well planned and weather information was obtained from the Bawtry meteorological office. Further, the pilot discussed his intentions with his CFI, who was also the tug pilot, and emphasised that he would not attempt to fly in cu-nimb cloud which had been forecast and, indeed, was visible from Sutton Bank. He did, however, propose practising instrument flying in suitable clouds.
The pilot had received formal training in instrument flying during his service as a pilot in the Royal Air Force. In spite of the pilot's competence and planning, he inadvertently entered a cu-nimb cloud which was obscured by medium cloud. He was unfortunate enough to intercept a cloud to ground type of discharge with currents in excess of 50,000 amps which would have raised the inside temperature of the wing to about 3,000 degrees C, causing the aileron cables to vaporise and an explosive pressure increase inside the wing.
It is now quite clear that lightning strikes are lethal and it is doubtful if the bonding required by the BGA would be effective against a strike of this magnitude. The fact that the strike occurred at the relatively low height of 7,800 ft would seem to indicate that one cannot determine if one is in acu-nimb merely by the height achieved.
It is not known if the pilot had any prior warning of the type of cloud in which he was flying, but it seems unlikely in view of the fact that he was in R/T contact with his crew and would probably have mentioned encountering static or seeing lightning.
The lesson to learn from this tragic: accident is that if thunderstorm activity exists or is forecast. it is extremely dangerous to enter even innocuous looking cloud. It is not known with any certainty why the pilot did not deploy his parachute. Evidence showed that be undid his safety harness and was probably ejected through the glider cockpit canopy by the forces resulting from the gyrations of the wrecked glider. There were no burn marks or other indications that the pilot was incapacitated by the strike.
Medical tests suggested that all injuries were sustained on ground impact. The most likely theory is that, following advice to delay opening his parachute until clear of cloud (to obviate the risk of being carried aloft in the updraught), the pilot was waiting for visual contact with the ground. Because he was in heavy rain and in all probability in a stable back fall position, he did not appreciate the proximity of the ground. A body has a higher terminal velocity than raindrops and this would cause great difficulty in looking down.
The rain would appear to the pilot to be coming up at him, obscuring his vision and possibly causing disorientation. In view of the history of the people being carried up in thunderstorms the advice to delay opening the parachute is quite sound. However, in the light of this accident it would be as well to warn pilots that confusion can exist in conditions of heavy precipitation and under these circumstances, failing to open the 'chute until too late is a real hazard.
ROGER A. NEAVES
Chairman, Safety Panel"
Sources:
1. http://www.yorkshire-aircraft.co.uk/aircraft/yorkshire/yorksother/1069.html
2. http://www.rcawsey.co.uk/skylark4.htm
3. https://en.wikipedia.org/wiki/Slingsby_Skylark_4
4. Sailplane & Gliding Magazine June-July 1967 issue, page 244: http://www.lakesgc.co.uk/mainwebpages/Sailplane%20&%20Gliding%201961%20to%201970/Volume%2018%20No%203%20Jun-Jul%201967.pdf
5. National Archives (PRO Kew) File AVIA 101/466 to AVIA 101/471 (6 files): https://discovery.nationalarchives.gov.uk/details/r/C5070476 to https://discovery.nationalarchives.gov.uk/details/r/C5070481
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 27-Sep-2008 01:00 | ASN archive | Added |
| 14-Dec-2012 16:56 | Dr. John Smith | Updated [Operator, Total fatalities, Total occupants, Other fatalities, Location, Phase, Nature, Departure airport, Source, Damage, Narrative] |
| 13-Nov-2019 20:54 | Dr. John Smith | Updated [Source, Narrative] |
| 13-Nov-2019 20:55 | Dr. John Smith | Updated [Narrative] |
| 29-Nov-2020 21:59 | Dr. John Smith | Updated [Time, Source] |
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