As Field Geographer, he traced colonial borders in Timor (1898), Zambezi (1900), Northern Angola (1901), Barotze (1902) and Tete (1904). By 1910, Gago Coutinho and Sacadura Cabral had established the Mozambican geodesic network all the way from Ponta do Ouro to Bazaruto, covering more than 32,000 km2. Finally, on 1 October 1912, twenty-two years after the signature of the Luso-British Treaty (11 June 1891), Gago Coutinho left for Lobito and the Benguela plateau in the company of Vieira da Rocha and Sacadura Cabral. He crossed the African continent on foot twice (around 5,200 km² from Angola to Mozambique). He demarcated more than 2,000 km of border using a pedometer and a compass, and triangulated areas covering more than 800 km². He returned to Lisbon in 1914, and the next year took his licence in France on a “Maurice Farman”. His first flight took place on 23 February 1917, at the School of Military Aviation at Vila Nova da Rainha. In September 1915, he was appointed head of the São Tomé Geodesic Mission, and in 1919, a full member of the Cartography Commission.