Aircraft and Pilot
The accident involved a Piper Cub J3C (L-4), registration HB-OFH, powered by a 65 hp Continental A-6 5 engine with a two-blade wooden propeller. The aircraft, owned by the Flugsportgruppe Zürcher Oberland, had a maximum takeoff weight of 550 kg and weighed 461 kg at the time of the accident, with its center of gravity within limits. No technical defects were found.
The student pilot, born in 1930, held a learner's permit for motor and glider aircraft since 29 July 1961, with an extension for solo cross-country flights under instructor guidance. He began motor flight training in June 1961 and had a total of 21 hours and 48 minutes of flight time with 152 landings, including 7 hours and 56 landings solo. His training included spiral exercises on 3 May (dual), 23 May (solo), and 15 July 1962 (dual). He had no theoretical or practical training in spin avoidance or recovery. His flying qualifications were unremarkable, with no prior incidents or violations.
The flight instructor, born in 1935, held a commercial pilot license since 24 February 1959, with an extension for training commercial pilots, and had approximately 1150 flight hours with 3300 landings. He had no recorded incidents or violations.
Accident Sequence
On Wednesday, 1 August 1962, the instructor scheduled flight duty with two students at Speck-Fehraltorf airfield. At about 1500, he briefed a planned outlanding at Lommis airfield. He assigned HB-OFH to the more advanced student, instructing him to practice spirals before landing at Lommis without further detail. The student had performed spirals twice dual and once solo previously without difficulty.
The flight departed at 1526. After a normal transit to Lommis, the student began spiral practice from 1000–1100 m above ground. He flew three left turns, regained altitude, then three right turns, then landed at 1546—on the third approach. In the debriefing, the instructor noted the spirals were wide; the student mentioned feeling slow during the second right turn. The instructor advised pushing the nose forward in such cases. For the return flight, the instructor set a similar program without precise spiral instructions.
The return flight departed Lommis at 1621. Over Speck, the student saw the other aircraft landing and began spirals from 1100 m. After three left turns, he climbed to 850 m and initiated right spirals northeast of the field. The instructor, while landing, observed the first spirals but then focused on landing.
The student reported that the first two right turns felt good, but during the third he again sensed slowness and pushed the nose forward. He initially thought the aircraft responded correctly, but it rapidly steepened into a dive and became unresponsive to control inputs. He lost control. At about 1650, the aircraft, in a relatively shallow bank with the engine running, struck a house on the main road between Fehraltorf and Pfäffikon. It tore down a garden fence, pivoted on the right wing, struck an eave with the tail, and came to rest against the house wall.
Damage
The student suffered severe jaw fractures, requiring three weeks of hospitalization, with full work incapacity for 1.5 months and half incapacity for another 1.5 months. The aircraft was destroyed. Damage to the fence, garden, and building was estimated at CHF 4500.
Investigation Findings
The investigation attributed the accident to the student pilot losing control of the aircraft during a spiral training exercise. The student, attempting to correct a perceived shallow spiral, lost situational awareness and control. The instructor's supervision and training thoroughness were noted as less than ideal, but it could not be determined that the accident would not have occurred otherwise. The student's starting altitude and entry were correct, and there was no evidence of careless action.