The crash killed three people -- including two from Merced County.
Federal investigators released a preliminary report Thursday, focusing on the radio communications between the two pilots trying to land.
A witness says the pilot of the approaching plane tried to turn but hit the wing of the smaller aircraft.
Another witness in an office actually snapped a photo that appears to show the collision before both planes fell from the sky.
Investigators say it could take up to two years for a final report to be released on the accident.