Introduction
On 9 June 1964, a Grunau Baby II glider, registration HB-195, sustained substantial damage during an outlanding near Holderbank in the canton of Aargau, Switzerland. The pilot was uninjured.
Investigation Details
The preliminary investigation was opened on 15 June 1964. The cantonal authorities did not conduct a separate investigation. The investigation was carried out under summary procedure according to the regulations on aircraft accident investigations.
Aircraft and Pilot
The glider, a Grunau Baby II, was owned and operated by Fliegerschule Birrfeld, Birrfeld (AG). It had an airworthiness certificate issued on 20 February 1964, valid until 14 July 1964. The aircraft weight was 250 kg. It was built in 1936.
The pilot, born in 1944, held a glider pilot license issued on 13 May 1963, valid until 14 May 1966. His flight experience totaled approximately 19.5 glider flight hours, of which 6.5 hours were accrued since 1 June 1964 during a course of preliminary flight training.
Weather and Location
The accident occurred at a location called Langmatt, between the towns of Wildegg and Holderbank, at an elevation of 350 meters above sea level. The weather was characterized by a high-pressure bise situation with horizontal visibility of 15–20 km and a moderate bise wind. The time was around 10:23 MEZ.
Flight and Accident Sequence
The pilot had been instructed during a weekly course to attempt a five-hour glider flight. He departed from Birrfeld at 10:23 MEZ. After more than three hours of flight, while in the area of Wildegg-Holderbank at an altitude of about 500 meters above ground, he suddenly encountered a strong downdraft of approximately 4 m/s. He intended to return to the Birrfeld airfield but realized that his altitude was insufficient to clear the Kestenberg ridge. He therefore decided to perform an outlanding. He selected a landing site and approached it. The landing was executed with a tailwind and with a slipping motion, resulting in a hard ground contact that caused the glider to break up.
Damage
The pilot remained uninjured. The glider sustained approximately 70–80% damage and was considered a total loss, as rebuilding the 1936-built aircraft was deemed not worthwhile. There was no significant ground damage.
Conclusion
The accident was due to the pilot approaching the chosen, not unsuitable landing area with tailwind and setting down too fast and with a slip.