The unresponsive Cessna jet that veered off course over Washington, D.C., plunged in a "near-vertical descent" into a Virginia mountain at a "high velocity" before bursting into flames, according to a federal report released Wednesday.
The National Transportation Safety Board's preliminary report offered few new details on the June 4 crash, which killed 4 people and caused military jets to scramble at supersonic speed to intercept the Cessna. But investigators were able to provide a more detailed timeline of the private jet's movements before the crash.
Shortly after takeoff, pilot Jeff Hefner made contact with the Atlanta Air Route Traffic Control Center and was given clearance for higher altitude, according to audio recordings reviewed by investigators. Hefner continued to read back instructions as the Cessna was cleared for higher and higher altitudes but stopped responding after a controller tried to amend a prior altitude clearance, the report added.
The jet then flew for about two hours before plunging into a mountain near rural Montebello, Virginia, about 60 miles southwest of Charlottesville, Virginia.
The wreckage "was extremely fragmented, scattered around a main crater, and evidence of a post-impact fire was observed," according to the report. Investigators were unable to find a cockpit voice recorder or flight data recorder at the crash site.
A final report that will provide details and conclusions about the accident, including probable cause, will likely take at least 12 to 24 months to complete.
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Timeline of Cessna's movements
The Cessna had departed from Elizabethton, Tennessee, at 1:13 p.m. and was headed to Long Island Mac Arthur Airport in New York, according to the report.
While Hefner and air traffic controllers initially maintained normal communication, the report said Hefner stopped responding after about 15 minutes when an air traffic controller instructed the pilot to stop his climb at 33,000 feet because of crossing air traffic.
But the jet climbed to 34,000 feet and leveled off, according to the report. Despite repeated attempts to contact Hefner, the Cessna flew past its intended destination in New York before changing its course and flying directly over the heavily restricted airspace of Washington, D.C.
According to a North American Aerospace Defense Command statement, six F-16 fighter jets were deployed and scrambled to intercept the Cessna, causing a loud sonic boom over the region. The fighter jets also attempted to contact the pilot with several radio transmissions and flare deployment, the report said.
Pilots of the fighter jets reported that Hefner appeared slumped over. Hefner and three other passengers died on impact.
Cockpit voice recorder not located
According to the report, maintenance inspection records showed that the jet was equipped with a cockpit voice recorder that could reveal what may have happened onboard. Investigators have not located the cockpit voice recorder.
The jet's cockpit was "destroyed" in the impact, the report said, adding that the plane was not required to be equipped with a flight data recorder. Outside experts and observers have theorized that a lack of oxygen inside the jet may have affected the pilot, causing him to lose consciousness.
"The most likely scenario right now is a pressurization failure or a mis-setting of the pressurization system," said Alan Diehl, an aviation psychologist who previously worked for the Federal Aviation Administration, the National Transportation Safety Board, and the U.S. Air Force.
John Rumpel, the owner of the Cessna jet, identified his daughter, Adina Azarian, granddaughter, Aria, and the granddaughter's nanny as the victims, along with the pilot. Rumpel also theorized that Hefner probably lost consciousness from a lack of oxygen.
Rumpel told the Associated Press earlier this month that Hefner had recently had a physical and he was not aware of any concerning medical conditions.
"He was top shelf, absolutely top shelf. I wouldn't have had my daughter and my grandbaby fly with him if he wasn't," Rumpel said Tuesday.
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Contributing: The Associated Press
This article originally appeared on USA TODAY: Virginia private plane crash: Aircraft plunged down at 'high speed'