HARTFORD, Conn. - A business jet flying over New England earlier this month violently pitched upward, fatally injuring a passenger, after pilots responding to automated cockpit warnings shut off a system that helps keep the aircraft stable, U.S. transportation investigators reported Friday.
The National Transportation Safety Board didn't reach any conclusions in its preliminary report on the main cause of the deadly March 3 accident, but it described a series of things that went wrong before and after the plane swooped out of control.
The report said that pilots followed a checklist and turned off a switch that trims or adjusts the stabilizer on the aircraft's tail, in response to several alerts in the cockpit of the Bombardier jet.
The nose of the plane then swept upward, subjecting the people inside to forces about four times the force of gravity, then pointing lower before pilots could regain control, the report said.
Pilots told investigators they did not encounter turbulence, as the NTSB had said in an initial assessment the day after the incident.
The trim system of the Bombardier Challenger 300 twin-engine jet was the subject of a Federal Aviation Administration mandate last year that pilots conduct extra safety checks before flights.
Bombardier did not respond directly to the report's contents, saying in a statement that it was carefully studying it. The Canadian manufacturer said it stood behind its Challenger 300 jets and their airworthiness in a previous statement.
The company said Friday that they will continue to support and provide assistance to all authorities as needed.
The two pilots and three passengers were traveling from Keene, New Hampshire to Leesburg, Virginia before transferring to Bradley International Airport in Connecticut. One passenger, Dana Hyde, 55, of Cabin John, Maryland, died from blunt force injuries.
Hyde served in government positions during the Clinton and Obama administrations, and was counsel for the 9-11 Commission, formally known as the National Commission on Terrorist Attacks Upon the United States.
It was not known whether Hyde was in her seat or up and about, in the cabin of the jet owned by Conexon, based in Kansas City, Missouri. Her husband and son, along with the pilot and co-pilot, were not injured in the incident, the report said.
A company specializing in rural internet, Conexon, has a representative who doesn't want to make a statement Friday.
The pilots canceled their initial takeoff because no one removed a plastic cover from one of the exterior tubes that determine airspeed, and they took off with a rudder limiter fault alert on, according to the report.
Autopilot stabilizer trim failure was reported by another warning. The report said the plane suddenly sipped upward as the pilots moved the stabilizer trim switch from primary to off while working through procedures on a checklist.
The report said that the plane's onboard computer thought that the plane was in danger of an aerodynamic stall, because the plane violently oscillated up and down and the stick pusher activated.
John Cox, a former airline pilot and now a safety consultant, said there were definitely issues with the pilots pre-flight actions, but he said they reacted correctly when they followed the checklist for responding to trim failure.
The flight crew was comprised of two experienced pilots with 5,000 and 8,000 hours of flying time and held ratings needed to fly for an airline. Both were relatively new to the model of aircraft, earning their ratings last October.
The FAA issued its directive about Bombardier Challenger 300 jets last year after multiple instances where the horizontal stabilizer on the aircrafts caused the nose of the plane to turn down after the pilot tried to make the aircraft climb.