Although primitive by today’s standards, the planes selected to fly over Mount Everest were a marvel of its day, with its supercharged Pegasus engine capable of soaring above 40,000 feet. The two biplanes had only rudimentary oxygen equipment and enough fuel on board for no more than 15 minutes flying time over the treacherous mountain. The lead aircraft was equipped with a fully automated Eagle III Williamson aerial camera to take the first images of the roof of the world. On the morning of April 3, 1933 flights took off from Lalbalu airstrip in the Indian state of Bihar, at about 8:30 a.m.
Chilled to the bone at an altitude of 31,000 feet, lead pilot Clydesdale maneuvered through the mountain range despite challenging downdrafts. Approaching Mount Everest, he realized he was off course: his PV-3 and the chase plane were on the wrong side of the peak. Battling powerful air currents, Clydesdale managed to guide the aircraft just over the top of the mountain range. The second crew, led by David McIntyre at the controls of a weaker Westfield Wallace airframe, scraped over behind him. Mount Everest was now dead ahead. Boosted by an upward draft of air, both pilots pushed the Pegasus engines to full power and soared past their objective. Clydesdale saw the top of Everest with his bare eyes, but the camera hadn’t delivered usable photos—dust problems, apparently.
Sixteen days later, on April 19, in a magnificent act of insubordination, they made another run. They cleared the summit again, noting the plume of snow streaming from Everest’s crest. And this time they got good pictures.
The benefits of the mission spread across a number of industries. Meteorologists learned a vast amount about the behavior of the environment at such altitudes and geographers gained an appreciation for the chiseled peak of Mount Everest (finally conquered in 1953 by Edmund Hillary and Tenzing Norgay). Even watchmakers, noticing how well the timepieces functioned, could claim a victory. Above all, though, the men inadvertently proved the need for pressurized cabins at high altitudes, a major factor in air travel to this day.
Reference:
This Day in History 