Thomas Stewart's Daughter, Sydney, Thought To Have Caused Helicopter Crash That Killed 5

A 2010 helicopter crash that killed five people was likely caused by a 5-year-old girl who kicked the controls, according to the National Transportation Safety Board.

Thomas Stewart, founder of Services Group of America, co-piloting the aircraft on a flight from his ranch in northern Arizona to his home in Scottsdale, the Associated Press reports. Investigators found that the 64-year-old allowed his young daughter, Sydney, to sit on his lap during the flight. A Nov. 7 report states it's "highly likely" that the girl pushed her foot down on the controls.

Officials believe either Stewart or the pilot responded by abruptly pulling up on the controls, which made the helicopter's main blade bend and hit the tail. The aircraft went down in a rural area near Phoenix, instantly killing everyone inside.

The accident took the lives of Stewart and his daughter, along with Stewart's wife, 40-year-old Madena Stewart; her brother, 38-year-old Mailang Abudula; and 63-year-old company pilot Rick Morton.

Residents who saw the helicopter fall told KTVK-TV that they saw parts flying off of the aircraft before it hit the ground.

Many witnesses called 911, according to the Seattle Times, reporting smoke, loud noises and falling helicopter pieces.

"It literally shook the windows in the house," John Hoeppner, who was at home about 200 yards from the crash site, told the paper.

Both Stewart's company and the family of pilot Rick Morton have challenged the NTSB's version of events, the AP reports. Morton's family believes that a faulty rotor blade fell apart mid-flight and caused the accident. They are suing Eurocopter, a company involved in repairing the blades after a prior issue.

Attorney Gary C. Robb says that Eurocopter "had some input" into NTSB's report. "Eurocopter conducted its own evaluation to exonerate itself," Robb told the AP.

Air-crash investigation professor William Waldock reviewed the report, and though he noted that a "sudden up and down" motion could have indeed causde the crash, he said there was no direct evidence that Sydney Stewart ever touched the controls.