A plane crash is a serious accident that occurs when an airplane has an unplanned landing or collision. A full investigation by the National Transportation Safety Board (NTSB) or other agency may be required to determine the cause of a plane crash. Plane crashes can be caused by pilot error, traffic control error, an act of God or a mechanical problem. Planes crashes that are caused by human error or mechanical failure may lead to lawsuits by plane crash victims or their survivors. Possible causes of action for a plane crash include negligence and product liability.