How Michael Spender Photogrammetrically Mapped Everest’s North Face — the 1935 Breakthrough

Michael Alfred Spender produced the first detailed photogrammetric map of Mount Everest’s North Face in 1935, combining some 1,200 aerial photographs with carefully measured ground control to produce contours accurate to roughly 15 metres. His work transformed Himalayan cartography and guided subsequent British approaches to the North Face for years.

Early life and training

Born in London on 11 November 1906, Spender was the son of Harold Spender, a Liberal journalist and biographer, and Violet Schuster, a painter and poet of German-Jewish origin. Violet died of influenza in 1921. Michael studied at Gresham’s School and read engineering at Balliol College, Oxford, graduating in 1928.

Surveying career before Everest

Spender’s surveying career began with practical assignments: between 1928 and 1929 he helped map Australia’s Great Barrier Reef for the Royal Geographical Society, living aboard the survey launch for 18 months. In 1932–33 he surveyed the fjords of East Greenland using overlapping aerial photographs — work that supported British territorial claims. He regarded mountaineering primarily as a tool for scientific surveying rather than a sport.

The 1935 Everest reconnaissance

After the 1924 deaths of George Mallory and Sandy Irvine, the Mount Everest Committee requested a new, accurate map of the North Face. For the 1935 reconnaissance the Royal Air Force loaned two Houston-Westland biplanes; Spender was appointed chief surveyor. The expedition included Eric Shipton (leader), Bill Tilman, Edmund Wigram, Charles Warren, a young Tenzing Norgay (then 21), Dan Bryant, Edwin Kempson and eleven Sherpas. Spender had only three weeks of preparation before heading into the field.

Instruments and methods

Spender relied on both aerial photography and precise ground control. He used two kinds of theodolites: a heavy Wild photo-theodolite (about 18 kg, with an integrated camera) for base control, and a lighter Watts-Leica (about 8.6 kg) to take fixes at high camps. Biplanes photographed the mountain at altitudes reported between roughly 8,200 and 8,800 metres while Spender directed exposures from an open cockpit, ensuring about 1,200 overlapping images.

Spender emphasized the importance of stereo pairs: "A single photograph is flat; the stereo pair restores the three-dimensional form of the mountain," he wrote. From stereo pairs a stereo-plotter can recreate the terrain in three dimensions and permit reliable contouring — provided the aerial images are tied to accurate ground control points.

Ground control and field work

On the ground, Spender established six primary stations at roughly 6,100 metres on the high pass now known as Lho La, tying the new images to fixed points first recorded in 1921. With Sherpa assistance he crossed icy Rongbuk streams at dawn to reach survey positions. He trained Shipton, Kempson and Warren in the use of the Watts-Leica so climbers could act as mountaineer-surveyors and map routes as they climbed.

"We forded the glacier-fed torrents at 4 am before the afternoon rise. By 7 am the water was waist-deep and dangerous," Spender recalled.

During the reconnaissance the team corrected significant errors in earlier quarter-inch maps — in places off by as much as half a mile — and extended ground surveys up the East Rongbuk Glacier toward Kharta Changri (7,035 m). While advancing, Charles Warren discovered the frozen body of Maurice Wilson, who had attempted a solo ascent the previous year.

Processing, publication and accuracy

Back in London Spender processed the field data using a Wild A5 stereo-plotter and sent film negatives to Copenhagen for contour plotting. He integrated Wheeler’s 1921 photographs and other earlier obliques, and used graphical methods to resolve peak heights. The final product — a 1:12,500 map published in the Geographical Journal — included 15-metre contours and rendered ridges, couloirs and icefalls with unprecedented clarity.

Contemporaries praised the result. Eric Shipton wrote that Spender produced a map they could trust, and later surveys found Spender’s contours to be remarkably consistent with more modern measurements.

Later work and wartime service

Spender returned to the Karakoram with Shipton in 1937 and compiled a larger 1:50,000 study, Environs of Mount Everest, in 1939 at the Wild factory in Switzerland. That compilation — covering hundreds of square kilometres with 100-metre contours — was lost for decades before its rediscovery in the Royal Geographical Society archives and later use in regional mapping.

During World War II Spender joined the Royal Air Force as a photo-interpreter. He developed a 3D stereoscope used to locate V-2 launch sites and to identify obstacles on the D-Day beaches; he was promoted to Squadron Leader in 1944.

Death and legacy

On 3 May 1945 Spender’s Avro Anson suffered engine failure and crashed near Süchteln, Germany. Severely injured, he died in hospital on 5 May 1945 at the age of 38 and was buried in Eindhoven Cemetery.

Spender’s insistence on rigorous ground control combined with stereo photogrammetry helped move surveying from a subsidiary expedition task to a core scientific discipline in exploration. His 1935 report and maps remain foundational in high-altitude cartography and influenced both later Himalayan surveys and wartime aerial intelligence work.

Personality and recollections

Accounts of Spender’s personality are mixed but consistent: his brother, poet Stephen Spender, described him as "cold and sharp" with a mind like "a steel trap" and little patience for sentiment. Some colleagues found him aloof or demanding; others, including Shipton, praised his energy, originality and underlying humility. Spender’s focus on precision and training helped popularize the idea of the mountaineer-surveyor — climbers equipped to gather scientific data as they ascended.