(Adds details of crowding, witness quote) By Emilie Ritter BUTTE, Montana, March 23 (Reuters) - The plane that crashed in Montana and killed all seven children and seven adults aboard had more passengers than seats, a federal official said on Monday. National Transportation Safety Board Acting Chairman Mark Rosenker said his team is investigating whether the 10-seat plane was carrying too much weight and why it nose-dived short of the runway in mountainous Butte, Montana. The single-engine plane had no "black box" flight data recorder and the investigation could take months. All the children were under age 10. Only one, a 1-year-old, by regulation could have been seated on an adult's lap for the flight. That left 13 people and 10 seats. "We are going to have to try and understand how, and why, there were three additional people on board the aircraft." Rosenker told reporters. He stopped short of saying the plane was overcrowded. Officials changed the number of passengers and seats aboard the plane as the investigation progressed. Rosenker said three families were in the Pilatus PC-12 turboprop plane heading from California to a ski vacation near Bozeman, Montana. Bozeman and Butte are towns of about 30,000 each in the mountainous western part of the state. The pilot, a 65-year-old man with years of flying experience, requested twice to divert to Butte from Bozeman, without giving a reason, and both times the Salt Lake City flight controller approved the change, Rosenker said. Rosenker said the plane appeared to have enough fuel. Witnesses, including Harley Howard, described the plane flying low and suddenly diving. "All of a sudden, the airplane tail lifted up and as it lifted, it spun around and was at a 90 degree angle to the ground, and the top of the airplane was facing us and just looked like someone took a hold of the plane and it just drove into the ground," he said. "There was a ball of fire when it crashed." (Reporting by Emilie Ritter, writing by Peter Henderson, editing by Bill Trott)
A grieving parent cries as she burns incense and her dead child's clothes in front of the rubble of the Beichuan Number One Middle School, located around 150 km (93 miles) ...
