Clearance and Handoff
Dulles Approach Control cleared the flight to Frederick VOR (FDK) at 4,000 feet and terminated radar control, handing off to Baltimore Approach Control. The flight was then cleared for the ILS runway 23 approach and instructed to report inbound on the approach.
Approach Procedure
The published approach procedure required the aircraft to fly outbound on the FDK 048-degree radial to the RICKE intersection/outer marker, execute a procedure turn (minimum altitude 2,300 feet), return to the outer marker on the ILS course (heading 229 degrees, minimum altitude 1,600 feet), and intercept the glide path.
Aircraft Maneuvering
Instead of following the procedure, the flight departed FDK on a northerly, somewhat erratic course. Baltimore Approach Control did not have positive radar contact; they received only two returns during the arrival and no returns below 3,800 feet. Abeam the RICKE intersection/outer marker, the aircraft maneuvered as if in a procedure turn. As it turned back toward FDK, the pilot reported "procedure turn inbound, runway 23" and was cleared to the advisory frequency. No further radio contact was established with the aircraft. The aircraft then turned west.
Collision with Terrain
After maneuvering for approximately eight minutes, the aircraft struck mountains about seven miles northwest of the airport at an elevation of 1,700 feet, on a heading toward FDK.
Radar and MSAW
Dulles Approach Control had radar contact with the aircraft, and a Minimum Safe Altitude Warning (MSAW) occurred before the accident. The Dulles controller did not attempt to alert Baltimore Approach Control or the pilot, but the MSAW occurred after the pilot had been cleared to the advisory frequency.
NOTAM
A canceled NOTAM for FDK was still issued as active, but the pilot was familiar with FDK as his home base.