The Cessna T310Q crashed shortly after takeoff. For clues into the cause of the crash, the press has focused on the fact that the pilot, Nouri Hijazi, had difficulty getting the engines started.
But what one witness had to say suggests that the plane was improperly loaded – specifically, it had too much weight in the back. According to the San Jose Mercury News, the witness watched the plane head off to the runway and saw something odd:
[The witness] said she watched uneasily as the plane slowly taxied for takeoff. As it did, the plane rocked back and forth, front to back, its tail nearly touching the ground.
That can happen when there is too much weight in the back of the plane. And when an aircraft is loaded such that is isn't in proper balance, it can become uncontrollable shortly after takeoff and enter an aerodynamic spin or stall, even with the engines developing full power. That is, though there engines are running fine, the aircraft will stop flying and simply fall out of the sky. Judging from the security camera footage of the crash, something like may have happened. The video show the aircraft "falling" rather than "flying."