Captain Thomas Neville Stack AFC (1 April 1896 – 22 February 1949) was a 1920s test pilot, air racer and aviation pioneer. He served in both the First and Second World Wars and in all three services. His son Neville Stack, born in 1919, became an Air Chief-Marshal in the Royal Air Force.
Thomas Neville Stack left the Army to join the Royal Flying Corps in 1917, at the end of the war he became a flying instructor. In 1921 he re-joined the Royal Air Force and served in Iraq leaving in 1925 to become chief flying instructor with the Lancashire Aero Club.
On 15 November 1926 Stack left England in at attempt to reach India in a De Havilland DH.60, he was accompanied by Bernard Leete in another Moth, they reached Karachi on 8 January 1927. In June 1927 Stack and Leete were each awarded the Air Force Cross, Air Ministry, 3 June 1927, The King had been graciously pleased to approve the award of the Air Force Cross to Mr. Thomas Neville Stack (Flying Officer, Reserve of Air Force Officers), in recognition of the distinguished service rendered to aviation by his recent flight in a light aeroplane from London to Delhi.
In 1934, to enable him to compete in the England-Australia MacRobertson Air Race, Stack together with Sidney Lewis Turner had a specially modified long-range version of the Airspeed Envoy (AS.6) built. It was named the Airspeed Viceroy (AS.8).
The Airspeed Viceroy started the race from RAF Mildenhall, England, but after several reliability problems including with the mainwheel brakes and the electrical systems, it was withdrawn from the race at Athens. The pilots concluded that it would be unsafe to proceed and they would probably be unable to finish the race. Subsequently, Stack started litigation against Airspeed, refusing to pay the balance outstanding on the aircraft. The Court found in essence that his claims of defects were a ruse to try and avoid payment, and he lost both his claim and Airspeed's counter-claim for the balance of the price of the aircraft and Stack & Turner were forced to return the aircraft (which later served in the Spanish Civil War) and pay substantial monies to Airspeed.