What happened
On October 24, 2015, a Brditschka Alpha, registration HB-YIQ, was engaged in a training flight at Birrfeld Aerodrome (LSZF). The flight was part of a session intended to help the aircraft owner resume pilot training after a three-year hiatus.
Following a pre-flight review of the aircraft's manual and technical characteristics, the flight instructor and the owner conducted several circuit laps. During the first circuit, the owner moved the landing gear lever to the intermediate position after extending the gear, citing concerns regarding the continuous operation of the electric motors and potential clutch wear. This action had not been previously agreed upon.
After completing three circuits, the crew taxied off the runway and performed a post-landing check. During this process, the landing gear guard switch was closed. The instructor, believing the gear lever was in the DOWN position, attempted to move the lever to the intermediate position; however, this movement inadvertently placed the lever in the UP position. While the guard switch initially prevented the gear from retracting, the owner subsequently deactivated the switch during a line-up check while stationary at the runway 08 holding point. This caused the nose gear to retract, resulting in the propeller striking the ground. There were no fatalities, though the crew sustained light injuries and the aircraft suffered damage to the propeller and nose gear.
The investigation
The investigation focused on the sequence of cockpit manipulations and the status of the landing gear safety mechanisms. Investigators examined the use of the landing gear guard switch and the movement of the gear lever during the post-landing phase and the subsequent taxiing procedures. The inquiry established that the instructor's attempt to adjust the lever led to the unintended UP setting, and the subsequent deactivation of the safety guard allowed the gear to collapse.