Lieutenant Colonel Eric Schults died from injuries sustained after the military aircraft he was flying crashed on Tuesday.

The US Air Force won’t reveal what aircraft he was flying.

It also took authorities three days before publicly announcing his death.

Both elements are highly unusual, especially given it came a day before two A-10C Thunderbolt II ground-attack aircraft crashed on the same weapons testing range. Both pilots managed to eject to safety.

"Information about the type of aircraft involved is classified and not releasable," Major Christina Sukach, chief of public affairs for the 99 Air Base Wing at Nellis, told military.com.

Schultz was a highly qualified former civilian test pilot who joined the US Air Force in 2001. He became the 29th pilot allowed to fly the F-35 stealth fighter in 2011.

All that is known about the aircraft that he was flying is that it was assigned to US Air Force Materiel Command.

This body administers research, development, testing and evaluation of both existing and future weapon systems.

Essentially, it runs US Air Force "black ops" and secret development programs.

Camera Icon An overhead view of work on the Area 51 facility.

The accident happened about 6pm local time as the unidentified aircraft was flying what was reported as a training mission over the Nevada Test and Training Range, about 200km northwest of the major Nellis Air Force Base.

A spokeswoman for the 99th Air Base Wing told local media Schultz died as a result of injuries sustained in the accident.

While the Nellis air base has tweeted statements relating to the crash of the A-10 attack jets, nothing has been mentioned about the accident which caused Lt. Col. Schultz’s death.

If the fatal accident involved an F-35 strike fighter, it would be the first involving the controversial and troubled aircraft. After suffering delays amounting to almost a decade, the aircraft has recently experienced dangerous engine fires -- including one incident which burnt its pilots head, neck and face.

But the possibility also remains open that he may have been flying a new or experimental aircraft out of Area 51, a highly secretive testing facility for futuristic designs which is contained within the Nevada Test and Training Range itself.

The base has undergone considerable redevelopment in recent years, with enthusiasts pointing to the construction of new and large hangars and support buildings.

Its existence was only formally admitted by the CIA in 2013.

- News Corp Network