After the war Alcock became a test pilot for Vickers and took up the challenge of attempting to be the first to fly directly across the Atlantic.
 Alcock and Arthur Whitten Brown took off from St John's, Newfoundland, at 1:45 pm local time on 14 June 1919, and landed in Derrygimla bog near Clifden, Ireland, 16 hours and 12 minutes later on 15 June 1919 after flying 1,980 mi (3,190 km).
The flight had been much affected by bad weather, making accurate navigation difficult; the intrepid duo also had to cope with turbulence, instrument failure, and ice on the wings.
The flight was made in a modified Vickers Vimy bomber and won a £10,000 prize (£462,900 in 2020) offered by London's Daily Mail newspaper for the first non-stop flight across the Atlantic.

A few days after the flight both Alcock and Brown were honoured with a reception at Windsor Castle during which King George V invested them with their insignia as Knights Commanders of the Order of the British Empire.

Alcock was present at the Science Museum in London on 15 December 1919 when the recovered Vimy aircraft was presented to the nation.
After the war Alcock became a test pilot for Vickers and took up the challenge of attempting to be the first to fly directly across the Atlantic.  Alcock and Arthur Whitten Brown took off from St John's, Newfoundland, at 1:45 pm local time on 14 June 1919, and landed in Derrygimla bog near Clifden, Ireland, 16 hours and 12 minutes later on 15 June 1919 after flying 1,980 mi (3,190 km). The flight had been much affected by bad weather, making accurate navigation difficult; the intrepid duo also had to cope with turbulence, instrument failure, and ice on the wings. The flight was made in a modified Vickers Vimy bomber and won a £10,000 prize (£462,900 in 2020) offered by London's Daily Mail newspaper for the first non-stop flight across the Atlantic.
A few days after the flight both Alcock and Brown were honoured with a reception at Windsor Castle during which King George V invested them with their insignia as Knights Commanders of the Order of the British Empire.
Alcock was present at the Science Museum in London on 15 December 1919 when the recovered Vimy aircraft was presented to the nation.
John Alcock (RAF officer)