What happened
While being vectored toward the final approach course for an ILS approach, the pilot activated the runway edge lighting. During the final approach phase, the pilot extended the landing gear and turned on the aircraft's landing lights. This action caused a glare within the cockpit, prompting the pilot to turn the lights off.
As the unspecified aircraft descended through 500 feet above the ground, the pilot turned the landing lights on for a second time. The pilot reported seeing a large glow and subsequently turned the lights off again. Following this second action, the pilot stated he could see nothing. The aircraft then collided with the ground and a Medium Intensity Approach Lighting System and Runway Alignment Indicator (MASLR) light stand.
The wreckage was located approximately 1 hour and 15 minutes after the impact. At the time of the accident, visibility was reported to be approximately 400 feet. The pilot had been aware of a NOTAM indicating that the VASI, REIL, and MASLR were inoperative.
Findings
An FAA CAMI optometrist reviewed the circumstances of the accident and determined the pilot experienced a classic case of flash blindness. Medical information indicated that under the specific circumstances encountered, the pilot would have experienced a blind gap in his visual field.