US officials have scrambled jet fighters in a supersonic chase of a light aircraft that violated airspace in the Washington DC area.
The jet fighters prompted a sonic boom over the US capital, causing alarm among people in Washington area, as they tried to catch up with the errant Cessna Citation, officials said on Monday (AEST).
A Cessna aircraft crashed into mountainous terrain in south-west Virginia about the time the sonic boom was heard in the capital, the US Federal Aviation Administration said. A Cessna Citation can carry seven to 12 passengers.
A US official said the jet fighters did not cause the crash.
A separate source familiar with the matter said the Cessna was believed to be on autopilot and did not respond to authorities.
Four people were on board the Cessna, CNN reported, citing an unnamed source.
The US military attempted to establish contact with the pilot, who was unresponsive, until the Cessna subsequently crashed near the George Washington National Forest in Virginia, the North American Aerospace Defence Command said in a statement.
“The NORAD aircraft were authorised to travel at supersonic speeds and a sonic boom may have been heard by residents of the region,” the statement said, adding that NORAD aircraft also used flares in an attempt to draw attention from the pilot.
The Cessna took off from Elizabethton Municipal Airport in Elizabethton, Tennessee. It was bound for Long Island MacArthur Airport in New York, about 80 kilometres east of Manhattan, the FAA said in a statement, adding that it and the National Transportation Safety Board would investigate.
The crash occurred about 3.30pm Sunday (local time), the FAA said. Virginia state police said later they were still searching for the downed plane.
According to the flight-tracking website Flight Aware, the plane appeared to reach the New York area and made nearly a 180-degree turn, with the flight ending in Virginia.
Air National Guard F-16s were deployed from Joint Base Andrews, ABC News reported, citing an unnamed US official. At least one military pilot saw that the Cessna pilot had passed out, ABC reported.
While rare, incidents involving unresponsive pilots are not unprecedented. Golfer Payne Stewart died in 1999 along with four others after the aircraft he was in streaked across thousands of kilometres with the pilot and passengers unresponsive. The plane eventually crashed in South Dakota with no survivors.
In the case of Stewart’s flight, the plane lost pressure, causing the occupants to lose consciousness because of oxygen deprivation.
Similarly, a small US private plane with an unresponsive pilot crashed off the east coast of Jamaica in 2014 after veering far off its course toward south-west Florida and triggering a US security alert that prompted a fighter jet escort.
On Sunday, the sonic boom caused alarm among many people in the Washington area who took to Twitter to report hearing a loud noise that shook the ground and walls. Several residents said they heard the noise as far away as northern Virginia and Maryland.
“We are aware of reports from communities throughout the National Capital Region of a loud ‘boom’ this afternoon,” DC Homeland Security & Emergency Management wrote on Twitter.
It said there was no threat to public safety.