CNN  — 

The co-pilot who fell to his death after getting off an aircraft mid-flight in North Carolina may have been sick and was described as “visibly upset” prior to exiting the plane without a parachute, according to a preliminary report from the National Transportation and Safety Board.

Two people – a pilot-in-charge and a second-in-charge – were initially on the July 29 flight, but only one person was on the plane when it landed, the Federal Aviation Administration said at the time. The body of Charles Hew Crooks, the 23-year-old second-in-charge, was discovered hours later in the backyard of a home in Fuquay-Varina, about 18 miles south of Raleigh, police said.

The plane, a twin-engine CASA CN-212 Aviocar, was being operated as a skydiving flight, the NTSB report said. It had already flown two skydiving runs and was on its way to pick up a third group. As Crooks flew the plane on its descent to Raeford West Airport, the plane descended below the tree line and “dropped,” according to the report.

While attempting to get the plane climbing again, the right main landing gear “impacted the runway surface,” causing a hard landing. The pilot-in-command took over controls from Crooks, reached over 400 feet again and directed him to declare an emergency and request a diversion to Raleigh-Durham International Airport for landing, the report said.

At this point, Crooks was responsible for communicating with air traffic control while the pilot-in-charge flew the plane. They hit turbulence while approaching the airport and about 20 minutes into the flight, Crooks “became visibly upset” about the hard landing, the report said.

The pilot-in-charge said Crooks then opened his side cockpit window and “may have gotten sick,” at which point the pilot-in-charge took over radio communications, the report said. Crooks lowered the ramp in the back of the airplane, indicating he “felt like he was going to be sick and needed air,” according to the report.

“The (pilot-in-charge) stated that the (second-in-charge) then got up from his seat, removed his headset, apologized, and departed the airplane via the aft ramp door,” the report said.

The pilot said there was a bar that Crooks could have grabbed about 6 feet above the ramp, but he never saw Crooks grab it before exiting the plane. The pilot turned the plane around to search for Crooks and notified air traffic control about Crooks’ departure from the plane.

The pilot proceeded with an emergency landing at the airport. On post-accident examination, the plane had substantial damage to the landing gear lifts and the airframe structure, the NTSB report said.

The plane has been retained for further examination, the report said, and the incident is still under investigation.

CNN’s Tina Burnside and Paradise Afshar contributed to this report.