Federal investigators have released their preliminary report of a Dec. 11 airplane crash that killed Ferriday, La., pilot Kenneth Netherland.

But the cause of the crash will not be determined for several months, said Tim Monville, an air safety investigator with the National Transportation Safety Board in Miami.

It will be six to nine months before Monville issues his factual report of the crash.

That will include more specific observations about the accident site, wreckage and engines, autopsy and toxicology reports, plane maintenance records and pilot experience.

&uot;After that, the NTSB Board in Washington will determine the probable cause of the crash,&uot; Monville said.

Making that determination could take anywhere two weeks to several months, he said.

Netherland was flying from Morristown, Tenn., to Natchez in a Cessna 310 he planned to deliver to Bland Greeson of Rayville, La. The plane crashed near Brooksville in Noxubee County.

The preliminary report, which was available on the Internet as of Friday, was half a page long and contained only basic information, such as witness accounts.

According to the report, one witness saw the plane fly overhead about three miles north of the crash site.

&uot;As the airplane got far away, she then heard popping sounds … for approximately five seconds,&uot; the report stated.

Another witness, who happened to be a pilot, saw the plane 1.25 miles north of the crash site, said he heard the plane’s throttles reduced and saw the plane’s nose tip up before the aircraft tipped to the right and went into a spin.

The plane then spiraled to the right. Its engines then resumed full power, and the plane flew in two circles level to the ground before falling again.

A witness who owns the property where the plane crashed was outside and heard the plane’s engine &uot;rev up,&uot; according to the report.

He said the plane crashed almost straight into the ground with its engines going &uot;full throttle,&uot; although the nose of the plane tipped up slightly before impact.

That witness also noticed a two-foot by four-foot object descending separate from the plane as it descended vertically.

Earlier this week, investigators said the door of the airplane had been separated from the plane, and they could not find it at the crash site.

NTSB reports are available on the Internet at http://www.ntsb.gov.