That same year he entered the Bleriot flight school in Étampes, gaining his pilot's license on 24 September 1910[2] In 1911 Gilbert was called up for military service and with only eight flying lessons made a corporal-aviator.

He was forced to leave the army after six months of service following a serious accident during a maneuver, and launched himself at once in sporting competitions where he quickly distinguished himself,[2] flying a Bleriot XI.

In the 1911 Paris to Madrid air race, Gilbert flew across the Pyrenees and was attacked by an angry mother eagle defending her young and nest; to ward off the large bird, he simply fired pistol shots at it rather than kill it.

The newspaper Airline Journal reported that flying over Brioude, Gilbert was shot at by an eighty-three year old farmer who took him for "Baret Lou", a demonic bird of prey that casts a curse on crops.

[2] On 24 April 1913 Gilbert made a record nonstop cross-country flight of 826 km (523 miles) from Villacoublay, France, to Vitoria-Gasteiz, Spain, in 8 hours 23 minutes.