Pilot Experiences Flash Blindness During ILS Approach (N225BA)

Approach and Lighting Activation The pilot was being vectored for an Instrument Landing System (ILS) approach when he activated the runway edge lighting. He reported seeing the lights while being vectored to the final approach course. During the final approach, he extended the landing gear and illuminated the landing lights. The lights caused cockpit glare, prompting him to turn them off. As the aircraft passed through 500 feet above ground, he turned the landing lights on a second time. He reported seeing a large glow and turned the lights off again. After doing so, he stated he saw nothing. The aircraft then collided with the ground and a Medium Intensity Approach Lighting System and Runway Alignment Indicator (MASLR) light stand. The aircraft was found approximately 1 hour and 15 minutes after the collision. A searcher reported visibility was about 400 feet. The pilot stated he was aware of a NOTAM regarding inoperative Visual Approach Slope Indicator (VASI), Runway End Identifier Lights (REIL), Medium Intensity Approach Lighting System and Runway Alignment Indicator (MASLR). An FAA CAMI optometrist was informed of the circumstances surrounding the accident. He stated that what the pilot experienced was a 'classic case of flash blindness.' Information provided indicated the pilot would have a blind gap in his visual field under the circumstances he encountered.