What happened
On January 18, 2012, at the Camarenilla airfield in Toledo, Spain, a collision occurred between a Robinson R-44 helicopter, registration EC-KDC, and a Cedimex S-6ES-582 ultralight aircraft, registration EC-CD7.
The helicopter, operated by Intercopters, was conducting a flight instruction session involving a simulated hydraulic failure maneuver. The instructor had selected a landing spot approximately ten meters off the right edge of runway 05, performing a low-altitude hover near the ground.
Simultally, the student pilot of the ultralight was performing solo instruction. After completing traffic patterns, the student landed on runway 05 and immediately initiated a takeoff roll. As the ultralight accelerated to approximately 55 mph, it passed parallel to the helicopter at an altitude of roughly 3 to 4 meters. At this moment, the ultralight's right wingtip dipped toward the helicopter, resulting in a contact between the aircraft's wing and the upper surface of one of the helicopter's main rotor blades. The student pilot regained control and landed immediately, while the helicopter crew heard a sound similar to a balloon bursting and observed the passing ultralight.
The investigation
The CIAIAC investigation focused on the aerodynamic interaction between the two aircraft and the operational procedures in use. The investigation established that the ultralight was not equipped with any air-to-air radio communication equipment. While the helicopter instructor had notified other aircraft in the circuit of the intended emergency maneuver, the ultralight pilot was unaware of the specific positioning of the helicopter's rotor wash.
Inspectors examined the damage to both aircraft. The Robinson R-44 sustained minor scratches to the paint on the upper surface of one rotor blade, but no structural damage was found following a maintenance inspection. The Cedimex S-6ES-582 suffered structural damage, specifically a tear in the fabric and structure of the right wingtip.
Findings
- The primary cause of the collision was the aerodynamic effect of the airflow (rotor wash) generated by the helicopter's main rotor acting upon the ultralight as it entered the helicopter's zone of influence.
- The student pilot was unaware of the aerodynamic impact caused by the downward airflow from a hovering helicopter.
- The ultralight aircraft lacked air-to-air radio equipment, preventing the pilot from receiving situational awareness updates from the helicopter instructor.
- The student pilot failed to abort the takeoff maneuver despite having the helicopter in sight, which would have avoided the collision as required by air traffic regulations.
Safety action
- REC 89/12: It is recommended that the State Agency for Aviation Safety (AESA) update ultralight pilot training programs to include instruction on the characteristics of wakes generated by airplanes and helicopters, specifically the effects of these wakes on ultralight flight stability.