Accident summary

On March 10, approximately 5 PM, an instructor was landing with a new student on a tandem flight at Marshall and hit unexpected sink during a top landing.  The sink caused a higher than expected descent rate at touchdown and the student lifted his legs at touchdown rather than using his legs to cushion the touchdown.  Student hit the ground on his tailbone and immediately stated he was in pain.

Conditions

The recorded winds at Marshall were 7-10 MPH south at 5 PM on July 10.

Emergency response

The pilot was driven to a hospital from Marshall.

Injuries

Compression fracture of the vertebrae

Damage

None noted

Pilot involved

The tandem pilot was properly rated to give commercial tandem instruction at Marshall.

Root cause

Unexpected sink caused higher than expected descent rate at touchdown

Proximate cause

Approach was toward the back side of the Marshall complex which increased the possibility of encountering sink conditions.

Corrective action

Instructor has improved his tandem prelaunch and prelanding briefings to emphasize that new PG pilots tend to pull up their legs as the ground approaches and it is important to overcome that tendency and keep one’s legs out.

Additionally, the instructor will only make tandem approaches at Marshall toward the front of the hill to minimize the chance of hitting sink.