What happened
On July 19, 2003, at Grenchen Airport, a Piper PA38-112 Tomahawk, registration HB-PGU, was taxiing along taxiway ECHO for solo training flights. At the same time, a Cessna 172 P, registration HB-CJM, had recently landed on runway 07 and was taxiing toward parking stand number 13.
The pilot of the Cessna 172 P had assisted a passenger in disembarking and was busy manually maneuvering the aircraft into its final parking position. Due to tight space constraints caused by nearby parked aircraft, the tail and left wing of the Cessna 172 P protruded into the taxiway area. As the Piper PA38-112 Tomahawk proceeded along the taxiway centerline, the student pilot attempted an evasive maneuver, but the left wing of the aircraft struck the passenger, who was walking near the tail of the stationary aircraft. The passenger sustained serious injuries involving internal trauma.
The investigation
The investigation examined the coordination between air traffic control and the aircraft involved, as well as the physical layout of the apron area. Investigators found that the air traffic controller was managing a runway change from runway 07 to runway 25, which required significant coordination. The view from the control tower toward parking stand 13 was obstructed by other parked aircraft.
Furthermore, the investigation looked into the parking procedures at stand 13. Because of limited space, aircraft were often parked in a manner that placed their wings and tails within the taxiway safety zone. It was also noted that the required safety line, intended to demarcate the taxiway boundary, was not visually present on the ground.
Findings
- The primary cause of the accident was the collision between the left wing of the taxiing HB-PGT and the passenger from the Cessna 172 P.
- Inadequate ground traffic coordination by the air traffic controller following the runway change, exacerbated by limited visibility from the tower.
- Insufficient situational awareness by the student pilot while taxiing through a congested area with restricted space.
- Tight parking conditions at stand 13, which forced aircraft to occupy the taxiway safety zone.
- A lack of visible markings on the taxiway to warn of potential hazards.
- Inadequate supervision of the passenger by the pilot of the Cessna 172 P during the parking maneuver.