First aeroplane pilot to break the human altitude record

The first person to break the human altitude record in a heavier-than-air aircraft was French test pilot Joseph Sadi-Lecointe. On 30 October 1923, Sadi-Lecointe flew to an altitude of 11,145 m (36,564 ft) in a modified Nieuport-Delâge NiD.40R fighter at Issy-les-Moulineaux Airfield in Paris, France.

Joseph Sadi-Lecointe was born to a working class family in Saint-Germain-sur-Bresle, a village in the Somme département in the far north of France. He trained as a welder and got a job at an aircraft factory near Paris as a young man. Sadi-Lecointe started taking flying lessons through his employer in 1910, and was granted a pilot's license on 10 February 1911.

During the First World War, Sadi-Lecointe flew first in a reconnaissance squadron and later – with the rapid development of air warfare – as a fighter pilot. He flew numerous missions over enemy territory and was shot down at least once, but in April 1915 (after nine months of flying in a war where pilot lifespans were often measured in days), the military recognized that this pre-war-trained pilot was more valuable as an instructor.

In 1917, Sadi-Lecointe was assigned to the Blériot-SPAD factory, where he worked as the primary test pilot for the successful SPAD S.VII and S.XIII fighters. He remained in this line of work after the war ended, moving to the Nieuport aircraft company in 1919. It was with the backing of this constructor that he began his record-breaking career.

He set his first record (for speed in level flight over 1 km) on 7 February 1920, recording an average of 275.86 km/h (171.41 mph) in a prototype Nieuport-Delâge NiD.29V biplane fighter. He would go on to set further speed records over 100 and 200 km with the same aircraft later that year.

He returned to record-breaking in 1923, raising the 1-km speed record to 375 km/h (233 mph) in a prototype Nieuport-Delâge NiD.42S fighter and decided to make an attempt on the absolute altitude record.

To achieve this, Sadi-Lecointe and his colleagues at Nieuport developed a special high-altitude variant of the NiD.29, which they called the NiD.40R. This aircraft had much longer wings (a wingspan of 14 m, as opposed to 9.7 m for the standard model) for better lift at high altitude, larger control surfaces on the tail (for better control in thin air) and a Rateau turbocharger to boost the pressure of the air coming into the engine (meaning it could survive at higher altitudes without the engine cutting out due to a lack of oxygen).

To prepare for his record attempt, Sadi-Lecointe spent time acclimatizing himself to extremely low air pressures in a decompression chamber, enduring simulated altitudes of up to 12,000 m for short periods.

After a few shakedown flights, Sadi-Lecointe made his first attempt at the record on 5 September 1923. He climbed to 10,741 m (35,239 ft) – a new record for a heavier-than-air aircraft, but just short of the overall altitude record of 10,800 m (35,433 ft), set by Arthur Berson and Reinhard Süring in 1901. Three days later he got even closer with a flight to 10,771 m. The final record-breaking flight was made on 30 October 1923, helped by the colder weather and some improvements to the aircraft.

In addition to his record attempts, Sadi-Lecointe was a famous air racer (winning the Gordon-Bennett trophy in 1920) and took part in several early motor-racing grands prix. He went on to become a senior figure in the French Air Ministry – a post he remained in until the fall of France in 1940. Refusing to collaborate with the Nazis, Sadi-Lecointe joined the French resistance, working with the Rafale (or Andromède) network until his capture. He was interrogated and tortured by the Gestapo at Fresnes Prison, Paris, before being released to l'hôpital Saint-Louis, where he died in July 1944.