What happened
On May 11, 2021, at 11:12 UTC, a student pilot was taxiing a Cessna F152, registration OK-VYR, at Prague Letňany Airport (LKLT). After landing on runway 05R, the pilot received instructions from the tower to expedite taxiing toward the fuel station to clear the area for an upcoming parachute jump operation.
In an effort to comply quickly with the instruction, the pilot transitioned from the grass area onto a paved taxiway. While following the yellow centerline, the pilot misjudged the distance to a stationary Robinson R44 helicopter, registration OK-BAD, which was parked near the edge of the pavement. The left wing of the Cessna F152 struck the fuselage of the helicopter, causing initial damage.
Following the first impact, the pilot failed to stop the aircraft immediately. The momentum caused the aircraft to veer further left, resulting in a second impact with the helicopter's anti-collision beacon and a third impact with the tail rotor. The collision caused the tail rotor to rotate despite the brake being applied. There were no injuries to any personnel, though the helicopter sustained significant damage and the aircraft sustained minor damage.
The investigation
The ÚZPLN investigation reviewed statements from the student pilot, the flight instructor, airport witnesses, and police records. The investigation also analyzed airport security camera footage and radio communications from the Letňany tower.
Investigators examined the positioning of the aircraft on the taxiway and the status of the parked helicopter. The investigation established that the Robinson R44 had been parked on the pavement for approximately 20 minutes, exceeding the 15-minute limit for that specific area without being marked as an obstacle. The investigation also reviewed the student pilot's experience level and adherence to taxiing regulations.
Findings
- The primary cause of the accident was the failure to adhere to ground movement regulations during taxiing.
- The student pilot's decision to use the paved taxiway to expedite the clearing of the runway for parachutists led to a misjudgment of the clearance required to pass the parked helicopter.
- A contributing factor was the improper positioning of the Robinson R44, which was parked in a manner that created the illusion of a safe passage along the centerline.
- The helicopter was not marked as an obstacle, despite having exceeded the permitted time limit for stationary use in that specific area of the airport.
- The pilot's failure to stop the aircraft immediately after the initial contact exacerbated the damage to the helicopter's tail rotor and beacon.