The probable cause of a 2016 private plane crash that killed all six people on board near Tuscaloosa Regional Airport has been determined to be the pilot’s fuel mismanagement and failure to follow the emergency checklist, according to the National Transportation Safety Board’s final report on the accident.

“It is likely the pilot failed to return the fuel selectors from the outboard to the inboard tank positions once the outboard tank were exhausted of fuel; however, the pilot misdiagnosed the situation as a fuel pump anomaly,” NTSB noted in the report, dated May 9.

The Piper PA plane with the pilot and five passengers on board was flying from Orlando, Florida, to its intended destination of Oxford, Mississippi on Aug. 14 , 2016 when the pilot requested a diversion to the Tuscaloosa Regional Airport around 11 a.m. The airplane never made it to the airport, crashing into trees about 1,650 feet short of the runway.

The pilot had requested the diversion after reporting a failure of the right engine fuel pump before later asserting that the plane had “lost both fuel pumps,” according to the NTSB report.

However, post-accident examination of the plane conducted by the NTSB revealed that none of the six fuel pumps on the plane “exhibited any anomalies that would have precluded normal operation before the accident.”

The NTSB report instead indicated that the pilot’s failure to switch from the outboard to the inboard tank positions once the outboards tanks were empty resulted in a loss of power to both engines due to a lack of fuel. 

“The National Transportation Safety Board determines the probable cause(s) of this accident to be: A total loss of power in both engines due to fuel starvation as a result of the pilot’s fuel mismanagement, and his subsequent failure to follow the emergency checklist,” the report stated.

The victims of the plane crash were three married couples returning from a dental conference in Florida. They left behind a total of 11 children.