The helicopter in a crash that killed one Federal Aviation Administration employee and critically injured another dropped 400 feet in a matter of seconds before losing radar contact, according to a report released Friday.

The preliminary National Transportation Safety Board report doesn’t speculate on what caused the accident. That’s typical for a preliminary report and it could be months before NTSB officials say why the helicopter went down in a Jackson neighborhood Sept. 1.

The crash killed Charles Farmer, a 59-year-old FAA employee from Wetumpka, Ala.

Larry Wells, 58, of Crystal Springs, Miss., remains at the University of Mississippi Medical Center in good condition, said Jack Mazurak, a hospital spokesman. Wells’ condition has been upgraded from critical following the accident.

The NTSB report doesn’t refer to either man by name.

The helicopter has dual controls and at least one of the pilots was in steady contact with an air traffic controller while practicing maneuvers at Hawkins Field, a municipal airport in Jackson, the report said. There’s no indication in the report they declared an emergency or told the controller there was a problem before the chopper went down.

The air traffic controller said the helicopter had performed a practice landing known as a “touch and go” and climbed back into the traffic pattern. She cleared the helicopter for another approach when a different aircraft requested to depart the airport, according to the report.

When the controller looked for the helicopter to “ensure traffic separation, she did not see it,” the report said. “She made several calls to the helicopter, but it did not respond.”

Radar indicated the helicopter dropped from 1,000 feet to 600 feet in about 9 seconds before its last radar contact, according to altitudes and times listed in the report.

A typical landing approach descent in that type helicopter — a Robinson R44 — would be closer to 500 feet per minute, Kurt Robinson, vice president of product support for Robinson Helicopter Company, said Friday in a phone interview.

Robinson said falling 400 feet in 9 seconds would be more typical of something striking the aircraft and it falling out of the sky, though he did not speculate on what happened in this case.

Two other pilots, who work for the Mississippi Department of Public Safety, were at the airport and watched the helicopter “falling rapidly.” One of them initially wasn’t concerned about how fast the helicopter was coming down, saying the Robinson R44 has a fast descent rate, the report said. But they soon agreed the helicopter was falling too fast and that it likely crashed when it disappeared below a treeline.

No one on the ground was injured.

Farmer and Wells were both experienced pilots and worked at the FAA office in Jackson. Wells had recently earned a national FAA inspector of the year award. Farmer was new to the job.

The NTSB tested fuel found in the helicopter and found no obvious contamination, the report said.