What happened
On August 24, 2014, at approximately 14:45 local time, two light aircraft collided in the airspace near Rickenbach, Switzerland. The first aircraft, a Cessna T210L with registration HB-CXK, was performing a flight from Zurich toward Hausen am Albis. Simultaneously, a Piper PA-28-181, registered as HB-OQW, was conducting a sightseeing flight originating from Lommis.
As the HB-CXK began a right-hand turn, the pilot observed the HB-OQW appearing on the right side, positioned approximately 50 meters away and 100 feet lower. The pilot of the HB-CXK immediately attempted an evasive maneuver to the left and upward. Simultaneously, the pilot of the HB-OQW recognized the approaching HB-CXK from the left and initiated a left turn to fly behind the other aircraft. Despite these efforts, the two planes collided at an altitude of approximately 3500 ft AMSL.
The impact caused significant damage to both aircraft. The right wingtip of the HB-OQW broke off, rendering the aircraft nearly uncontrollable. The pilot was forced to perform an emergency landing in a field near Bronschon/SG. While there were no fatalities in the HB-CXK, the collision resulted in 4 serious injuries and 0 fatalities among the occupants of the HB-OQW, and 2 serious injuries and 1 light injury aboard the HB-CXK.
The investigation
The Swiss Transportation Safety Investigation Board (SUST) examined radar data, pilot statements, passenger testimonies, and eyewitness accounts. The investigation focused on the flight paths of both aircraft, including a third aircraft, a Mooney HB-DGG, which was also in the vicinity and had observed the Piper but did not see the Cessna.
Findings
- The primary cause of the collision was a lack of proactive airspace surveillance by both pilots.
- A significant systemic factor was that neither aircraft was equipped with an airborne collision warning system.
- On the HB-OQW, the pilot had not tasked the passengers with assisting in visual lookout duties.
- During the approach, visibility for certain occupants was obstructed; for example, a passenger in the HB-CXK was focused on instruments rather than the external environment at the critical moment.