Houston–Mount Everest flight expedition

In 1919, Jean Casale made the first flight to exceed the altitude of Everest, but only for a short period, and actually flying over the mountain would be far more challenging.

The main limitation of high altitude flight at this time was keeping the crews alive in the low pressure and cold temperature air.

[4] Buchan approached Lord Clydesdale (MP for East Renfrewshire) to suggest a flight over Everest that would promote British aviation.

[6] The inventor Stewart Blacker joined the expedition; he was an experienced pilot who had served in the British Indian Army from 1907 to 1932 (reaching the rank of major), so was familiar with the region.

[2] Fellowes and Blacker obtained the necessary permissions from the Air Ministry, India Office and the government of Nepal to allow the flight to occur.

[2] Blacker also convinced the Royal Geographical Society that a flight would provide valuable information for the planned 1933 British Mount Everest expedition, which aimed to climb to the summit.

The crews wore multiple layers of sheepskin clothing and the aircraft were modified to provide connections for heated flying suits.

[4] The crews then flew the aircraft to Purnea, in Bihar state, where they were based at Lalbalu Airfield, approximately 50 miles (80 km) south of Mount Everest.

[2] While they awaited clear weather, the expedition crews relaxed by swimming, until an encounter with a crocodile required McIntyre to shoot the animal.

[3][10][11][12] After 9 am they reached their maximum altitude of 31,000 ft (9,400 m) as they passed over Lhotse,[2] the fourth-highest mountain in the world, located two miles south of Everest.

[10] Bonnett briefly lost consciousness due to hypoxia after damaging his oxygen line;[3] he successfully repaired the leak with a handkerchief.

"[7] The aerial photographs were obtained too late to assist the 1933 British Mount Everest expedition, which had already reached Rongbuk Monastery – on the other side of the Himalayas from the airfield – and was ultimately unsuccessful.

The photographs were made public in 1951[3] and were used by Edmund Hillary and Tenzing Norgay to plan their route to the top of Mount Everest, which they successfully climbed in 1953.