Federal investigators say the pilot in a deadly small plane crash near Mt. Hamilton last year failed to maintain adequate air speed while flying in a canyon.
The National Transportation Safety Board on Tuesday issued findings of its investigation into the April 18, 2009 crash that killed 53-year-old pilot David Hartley and 49-year-old John Bergsma. Both were from Wilton in Sacramento County.
The agency says the failure to maintain airspeed caused the plane to stall or spin before it crashed.
The NTSB also released its findings into three other fatal plane crashes in Northern California.
The agency found that Kenneth Gottlieb, a San Francisco man who died when his plane crashed into a hillside vineyard in Napa County last August, lost track of where he was after takeoff.