The US Federal Aviation Administration and Gulfstream Aerospace have confirmed one of the manufacturer's five G650 test aircraft has crashed at Roswell International Air Center Airport in Roswell, New Mexico, killing two pilots and two test engineers aboard.
According to the FAA, the aircraft - operating as Gulfstream Test 31 - had spent the morning, approximately 2.5h, conducting takeoff-performance and brake testing when it was cleared for takeoff on runway 21, at around 09:30 local time.
On its take-off roll the aircraft had "just gotten airborne" when the right wingtip struck the ground, causing the aircraft to lose altitude, collapsing the gear, skidding on the runway and catching fire.
The FAA says winds were under 10kts at the time of the accident.
Gulfstream Aerospace president, Joe Lombardo, says: "Our thoughts and prayers go out to the families of those who were lost. We are cooperating 100 percent with the investigation."
Both the National Transportation Safety Board and FAA investigators are enroute to the scene.
A source familiar with the accident says S/N 6002, registered N652GD, was the airframe involved. S/N 6002 first flew on 25 February 2010 and was tasked with validating the aircraft's systems, as part of the planned 1,800h certification campaign.
Gulfstream has targeted 2011 for FAA and EASA certification of the large cabin ultra-long range G650, with its first planned delivery in 2012.
Gulfstream has identified the four crew members killed in the crash as experimental pilots Kent Crenshaw (64) and Vivan Ragusa (51) and technical specialists David McCollum (47) and Reece Ollenburg (48).