Paul J. Richards/AFP, Getty Images

The CV-22 Osprey aircraft combines the vertical takeoff, hover and vertical landing qualities of a helicopter with the long-range, fuel efficiency and speed characteristics of a turboprop aircraft.

Military officials are investigating the cause of a CV-22 Osprey crash on Wednesday evening that hospitalized all five crew members, according to the public affairs office at Hurlburt Field, a base located in the Florida panhandle.

The Osprey aircraft, which is designed for vertical take-off and landing like a helicopter, with long-range cruise capabilities of a twin turboprop aircraft, was on a routine training mission when it crashed north of Navarre, Fla., in a 725-square-mile area the military refers to as Eglin Range.

"This particular mission was a gunnery training mission, so it was a two aircraft formation out performing gunnery," said Col. Jim Slife, 1st Special Operations Wing commander, at a news conference Thursday morning. “When the lead aircraft turned around in the gun pattern, they did not see their wingman behind them so they started a brief search and found they had crashed right there on the range.”

Four of the five crewmen were listed in stable condition, and one was in "guarded"condition, Slife said.

An Air Force board will investigate to determine the cause of this crash, which is the latest in a string of incidents that raise questions about the aircraft's safety record.

The Osprey is designed for vertical take-off and landing like a helicopter, with long-range cruise capabilities of a twin turboprop aircraft.

In another recent incident, a Marine Corps version of the aircraft, an MV-22 Osprey, went down in April during a training exercise in Morocco, the Associated Press reported.

That crash caused a delay in the deployment of 24 of the aircraft to U.S. Marine Corps Futenma Air Station in Japan's Okinawa after Tokyo called for a safety review, AP said. 

The CV-22 Osprey’s mission is to conduct long-range infiltration, exfiltration and resupply missions for special operations forces, according to the U.S. Air Force web site.

The Air Force version is equipped with a missile defense system, terrain-following radar, a forward-looking infrared sensor and other electronic gear that enable it to avoid detection and defend itself on special operations missions over enemy territory, AP reported.

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