GUTHRIE, Oklahoma - Federal investigators blame the pilot for a plane crash that killed him, critically injured his son and also hurt his grandson.

Darrell Allen Smittle, 62, died when his single-engine Piper PA28 crashed on the afternoon of October 16, 2011 near Guthrie.

Smittle's son, 41-year-old Darrell Stewart Smittle, and his grandson, 11-year-old Joshua Smittle, survived the crash.

The three were returning from a fishing trip in Arkansas when the crash happened. 

According to the National Transportation Safety Board's Probable Cause report, the airplane crashed because it ran out of gas.

The NTSB says the airplane was fueled to capacity, which was 50 gallons, two days before the fatal flight.  The investigator says the plane was flown for three hours and 15 minutes to its destination.  Two days later, the airplane flew for three additional hours, but was not refueled beforehand.

The NTSB says that during that flight, one of the younger Smittles heard the pilot say they were low on fuel.  Shortly thereafter, the engine lost power and the airplane hit power lines then crashed into a storage shed.

According to the report, the airplane was equipped with two 25-gallon fuel tanks.  The report says the airplane would have burned between 38 and 52 gallons for the two flights.