On arrival overhead Blackpool, on the final sector of a scheduled passenger flight from Dsseldorf, via Amsterdam and Newcastle, all the aerodrome lights were visible from the aircraft at a height of 1,500 ft. At this time, however, the pilot was advised by the Blackpool air traffic controller that there was a layer of fog over the airport, and that visibility at the threshold of runway 10 was estimated as 100 yds. or less. After making three circuits of the aerodrome, the captain decided – from his own in-flight observation of the aerodrome lights – that the visibility was adequate for an approach and landing on runway 10. During the final approach some of the runway lights became obscured and, on crossing the runway threshold, the aircraft entered a shallow layer of fog. As the aircraft was flared for landing, the captain switched on the landing lights. The reflection of these lights in the fog dazzled both pilots, causing them to lose visual reference. Shortly after touch-down the aircraft veered off the left hand side of the runway and, after running over rough ground, the port wing struck a small brick building. The aircraft slewed to the left and came to rest 100 yds. further on, with the outer section of the port wing broken off. OPINION: “The accident was the result of an unintentional change of direction after both pilots lost visual reference when the commander switched the landing lights on during fog.”