CALGARY - The Transportation Safety Board says the pilot of a plane that crashed, killing former Alberta premier Jim Prentice, was probably disoriented.

The Cessna Citation jet went down shortly after takeoff from Kelowna, B.C., on its way to the Springbank airport west of Calgary in October 2016.

The TSB says there were no flight recording systems on board the aircraft, so it could not definitively determine the cause of the crash.

But the safety board says the "most plausible scenario" is that pilot Jim Kruk became spatially disoriented due to a heavy workload at the controls.

Kruk, a retired RCMP officer, optometrist Ken Gellatly, the father-in-law of one of Prentice's three daughters and Calgary businessman Sheldon Reid all died with Prentice.