What happened
On June 11, 1995, a glider towing operation near Presidente Bernardes, São Paulo, resulted in a fatal accident. During the initial climb, the IPE-02B glider gained excessive altitude relative to the towing aircraft, causing the tow cable to slacken. As the cable subsequently tensioned, the sudden jerk caused the towing aircraft to enter an abrupt nose-down attitude, leading to an engine failure due to fuel starvation caused by the abnormal flight attitude.
The pilot of the towing aircraft initiated an emergency descent but failed to disconnect the tow cable. While the glider pilot eventually disconnected the cable, the glider had already entered a steep dive. In an attempt to recover, the glider pilot likely exceeded the maximum never-exceed speed (VNE) of 190 km/h and deployed the aerodynamic brake. The resulting aerodynamic pressure caused the right wing's brake mechanism to fail and the right wing to detach from the aircraft shortly before impact. The glider struck the ground at an angle of approximately 60 degrees, resulting in two fatalities.
The investigation
CENIPA investigators examined the wreckage and flight logs, establishing that the towing aircraft, an Aeroboero AB-1180, managed to perform an emergency landing at the Presidente Bernardes airfield without significant damage. The investigation focused on the sequence of the cable slackening and re-tensioning, the mechanical failure of the glider's wing, and the operational qualifications of the crew. Investigators also noted that the airfield in use was technically closed for operations at the time of the accident.
Findings
- The pilot of the towing aircraft was not qualified for glider towing operations.
- The glider pilot lacked the necessary experience to operate from the rear cockpit position, which has significantly restricted visibility of the tow plane.
- The towing pilot failed to disconnect the cable during the emergency maneuver.
- Improvisation and complacency regarding standard operating procedures and safety regulations were present in the actions of both pilots.
- The glider exceeded its VNE, leading to the structural failure of the aerodynamic brake and the separation of the right wing.
- There was a lack of mission briefing regarding emergency procedures between the two crews.