JEFFERSON CITY, MO. Aviation investigators said Wednesday there was a wind shift before the plane crash that killed Gov. Mel Carnahan, his son and an aide.
The National Transportation Safety Board said the shift occurred about the altitude the plane was flying before it went down. Officials said their examination of the plane's two engines had not provided any conclusive information about the cause of the Oct. 16 crash.
The NTSB also said it is investigating pilot Roger "Randy" Carnahan and his training, flying habits activities for the 72 hours before the accident. The governor's eldest son was killed along with Chris Sifford, a longtime aide.
Relatives of the Carnahans and Sifford have sued alleging the crash was caused by a failed vacuum pump and manifold system on the Cessna 335.
The system helps control the plane's directional gyroscope, which tells pilots what direction the plane is flying, and the artificial horizon, which is used to help maintain level flight.
The NTSB said examinations of the right engine vacuum pump and pieces of the left engine did not produce any conclusive information. The investigation continues.
The NTSB has said Roger Carnahan told air traffic controllers he was having problems with the plane's artificial horizon during the flight. Twelve minutes later, the plane dropped from about 7,100 feet to 3,900 feet in nine seconds, then disappeared from radar, NTSB officials said.
The NTSB said the wind shift occurred about 7,000 feet.