What happened
On Friday, August 24, 2001, at 17:30, an Avid Flyer ultralight, registration 63-KD, was conducting a training flight from Montmorillon to Ambert. While cruising at flight level 55, the crew contacted Clermont-Ferrand approach to request transit through the southern portion of the Class D TMA. During this communication, the controller alerted the pilots to the departure of two regional transport aircraft heading east and south.
As the crew navigated the airspace, they observed an Embraer 145 climbing on a path that intersected their route approximately four to five kilometers ahead at a similar altitude. Shortly after, a second aircraft was spotted climbing directly toward the Avid Flyer. While the instructor prepared to notify air traffic control of the potential conflict, the ultralight began a progressive left yaw.
Despite immediate corrective rudder inputs, the left yaw accelerated into a flat spin. The instructor attempted to recover by pushing the control stick forward, causing the aircraft to dive while continuing the rotation. Realizing control could not be regained, the instructor pulled the stick back to level the aircraft's attitude and deployed the emergency parachute. The aircraft descended for approximately 20 to 30 seconds before impacting the Allier river at an altitude of roughly 250 meters. Both occupants successfully evacuated the wreckage and reached the riverbanks.
The investigation
The investigation focused on the sequence of events leading to the loss of control and the subsequent impact. Investigators examined the flight path, the proximity of the Embraer 145, and the mechanical performance of the aircraft and its emergency systems. The investigation also looked into the communication failures during the descent and the aircraft's equipment configuration.
Findings
- The primary cause of the loss of control was the aircraft's encounter with the wake turbulence generated by the Embraer 145, which crossed the ultralight's path at a similar altitude.
- The deployment of the emergency parachute caused the coaxial radio antenna cable to break, which prevented the crew from transmitting distress messages during the descent.
- The aircraft was not equipped with a transponder.
- The impact resulted in damage to the left main landing gear and the fuselage.