Soon after the invasion the Germans began with the construction of an aerodrome on the territory of Melsbroek, near the Belgian military back-up airfield "Steenokkerzeel".
Where until September 1940 there used to be a windmill the new Fliegerhorst Melsbroek emerged.
By March 1943 the Luftwaffe could already make use of three paved runways. After the liberation (3 September 1944) Spitfires, Wellingtons, Mosquitos and Mitchells used the same runways.
The village of Melsbroek severely suffered from the allied bombings. On 10 April 1944 21 innocent civilians died.
Much of the German infrastructure at Melsbroek fell into the hands of the British and would directly after the war become the centre of civil aviation in Belgium. Many of the first post-war passengers were British POWs returning to their fatherland. They were repatriated by converted B 17 bombers of the Swedish ABA (Aktiebolaget Aerotransport), the so-called Felix flights.
After the Second World War the most of the civil aviation activities were moved from Haren to Melsbroek. However, Sabena continued to have its aircraft such as the DC-4 serviced at Haren until the 1950s. To take off with passengers the pilots had to drive their aircraft on the kilometres long taxiway from Haren to Melsbroek. Sometimes they flew empty between the two aerodromes. Between 1947 and the beginning of 1949 all scheduled airlines left Haren for Melsbroek. The civil aerodrome of Melsbroek was officially opened by the Prince Regent on 20 July 1948.
In the post-war years the Belgian airways agency "Regie der Luchtwegen/Régie des Voies aériennes" (RLW/RVA), created on 20 November 1946, worked very hard to give Belgium a civil airport with international flair.
Very soon trendsetting airlines such as Pan American World Airways (PAWA) landed at Melsbroek.
New aircraft hangars were constructed near the Haachtsesteenweg (Fromson/Herpain, now used by the 15th Wing Air Transport) and by the end of the 1940s also on the territory of Zaventem (Strabed, now used by DHL and SN Technics).
In the year 1950 the aerodrome in Melsbroek registered 240,000 passengers (less than the number of passengers that in 2015 depart from Brussels Airport in a single week).
As from 1951 guided tours of the airport were organised for an ever growing group of interested people, the precursors of the guided tours currently organised by Brussels Airport Company. The one-hour tour was preceded by a documentary film shown in their own movie theatre. Many visitors went to the "Moeder Avia" bar to have a "Geuze Lambic" and a slice of bread with curd cheese.
On 15 May 1955 the young King Baudouin officially opened the railway link between the city centre of Brussels and Melsbroek, after which "Bwana Kitoko" left for his first triumphant trip to the Belgian colony Congo.
Ours definitely was the first airport where rail and air transport were perfectly integrated. Passengers could check in at the Sabena Air Terminus at the Central Station, take the train to the airport and get on board of their propliner without having to worry about their luggage. Sabena even had set up a helicopter network that took passengers to the heart of Brussels, the Groendreef heliport or the world exhibition.