On June 27, 2001, a Piper PA-38-112 (registration N9341T) was involved in an aviation accident near Bozeman, MT. Investigators recorded the probable cause as: The collision was caused by an updraft during formation flight maneuvers, leading to an unexpected ascent of one aircraft into the propeller of another. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
Two aircraft collided during formation flight maneuvers when an updraft caused one plane to ascend into the propeller of another, resulting in damage to both but safe landings.
What happened
The pilot reported that while maneuvering for a formation flight, his aircraft encountered an updraft and ascended up to the second aircraft. The propeller of the second aircraft contacted the horizontal stabilizer of the first aircraft. Both aircraft were able to return to the departure airport and land without further incident.
The investigation
The investigation revealed that the collision occurred due to the unexpected vertical movement caused by the updraft during formation flight maneuvers. There was no indication of mechanical failure or pilot error in the execution of the formation flight itself.
Findings
The aircraft involved were engaged in a formation flight maneuver.
An updraft caused one aircraft to ascend unexpectedly.
The propeller of the second aircraft contacted the horizontal stabilizer of the first aircraft.
Both aircraft returned to the departure airport and landed safely.
Safety message
Formation flight maneuvers require careful coordination and awareness of environmental conditions such as updrafts, which can cause unexpected vertical movements. Pilots should be prepared for such scenarios and maintain situational awareness to avoid collisions.
Probable cause
The collision was caused by an updraft during formation flight maneuvers, leading to an unexpected ascent of one aircraft into the propeller of another.