What happened
During an approach to Valday under adverse weather conditions, a U-2 aircraft encountered another Soviet Air Force plane. The second aircraft was also a U-2 with registration 7, which was carrying two individuals. A mid-air collision occurred between the two machines. Following the impact, both airplanes lost control and descended rapidly to the ground. They crashed approximately 15 kilometers west of Valday. The force of the impact destroyed both airframes completely. All three people aboard the two aircraft were killed in the accident.
Findings
Investigations into the incident revealed that operational security protocols contributed significantly to the event. Both aircraft were flying with all external lights extinguished. This measure was taken specifically to prevent detection by potential enemy forces, which severely reduced visibility and situational awareness for the pilots during the approach phase.