National Transportation Safety Board investigators were investigating Friday a plane crash that killed a St. George pilot Thursday.

The victim, whose name is being withheld pending notification of relatives, died when his single-engine plane crashed 6 miles south of Milford. There were no passengers.Lee Fryer, Seattle Federal Aviation Administration, said the Piper was flying from Provo to St. George when it disappeared from Salt Lake air traffic controllers screens at 3:26 p.m. Attempts to establish radio contact failed.