The Cunard Eagle Vickers Viking took off from London at 13:29 GMT on a charter flight to Stavanger, Norway. Nearing Stavanger, the flight was given descent instructions in preparation for an ILS approach. The ILS runway at Sola Airport had a magnetic bearing of 185ø. The outer marker was positioned 3.8 NM from the runway threshold. When approaching from the south the prescribed procedure is to cross the outer marker at 2000 ft (QNH) and fly north for 2.5 NM, descending to 1500 ft (QFE). A 45ø procedure turn is then made to the left and after 45 seconds this is followed by a turn to the right to rejoin the localizer beam. On re-joining the localizer, the aircraft descends to 1300 ft and, after crossing the outer marker, descent is continued on the glide slope to the approach minimum. At 16:18 hours the aircraft overflew the airfield to the north. The last surface wind given to the aircraft was 200ø/25 kt. However, evidence indicates that at this time a considerably stronger wind existed at the 1600 ft level and the aircraft’s maximum angle of drift, while on the procedure turn, may have been as high as 26ø. The aircraft likely followed the ILS approach procedure by turning left and then right after passing the outer marker. For some reason the aircraft began to track 105ø instead of 185ø for the ILS. The aircraft continued until it impacted Holteheia, a steep mountainside running in a north-south direction, at an elevation of 1600 feet. PROBABLE CAUSE: “For reasons unknown, the aircraft deviated from the prescribed flight path.”