The National Transportation Safety Board (NTSB) said it began conducting an investigation into the mid-air collision of two historic war planes which occurred during an airshow in Dallas, Texas, on Saturday, November 12.The collision happened at the Wings Over Dallas WWII Airsho​w ​at the Dallas Executive Airport Terminal, killing five crew members of one plane and the pilot of the other.At an NTSB media briefing on November 13, board member Michael Graham said an investigation has been launched, and a preliminary report of the accident is expected in four to six weeks.“Neither aircraft was equipped with a flight data recorder or a cockpit voice recorder, often known as the black box,” Graham said.Given the lack of flight data records, Graham said that videos of the incident from witnesses will be “very critical.”Footage released by the NTSB shows debris from the plane crash and scorch marks on the ground. Credit: National Transportation Safety Board via Storyful