The 1948 B-29 Lake Mead crash occurred July 21, 1948 when a Boeing B-29-100-BW Superfortress, modified into an F-13 reconnaissance platform and performing atmospheric research, crashed into the waters of Lake Mead, Nevada, USA.

After completing a run to 30,000 feet (9,100 m) east of Lake Mead, the crew began a descent and leveled out just over 300 feet (91 m) above the surface of Lake Mead. The crew described the lake as looking like a mirror, with the sun reflecting brightly off the surface. These conditions make judging height above a surface considerably more difficult. The aircraft then slowly began to descend below 100 ft (30 m) until it struck the surface at 250 mph (400 km/h) and started skipping along it. Three of the aircraft's four engines were ripped from its wings and the fourth burst into flames. The aircraft managed to gain around 250 ft (76 m) but then settled back onto the water's surface in a nose-up attitude and slowly skiing to a stop. The five-man crew then bailed out into two life rafts and watched the aircraft sink in a virtually intact condition.

The crew was rescued from the lake six hours later and was instructed not to disclose any details of the flight, its mission or its loss. As the mission was classified, these details were not released until fifty years later.