Air Congo was originally formed in June 1961 as the national airline of the Congolese Republic, with Sabena providing both technical assistance and equipment. Initially, the Congo government had a 65% participation in the airline, Sabena had a 30% holding, and Air Brousse and Sobelair held the balance.

Services to Belgium were inaugurated in early 1963, linking Léopoldville with Brussels via Rome, using Boeing 707 equipment operated by Sabena on behalf of the carrier. By 1964 the airline was also operating Curtiss C-46s and DC-4s equipment, leased from Aerovias Panama Airways to complement the Sabena-leased aircraft.

After the Republic of the Congo gained independence from Belgium in 1960, the Belgian national airline Sabena continued to operate routes in the country. Plans for the formation of a Congolese airline were delayed due to the Congo Crisis; however, in January 1961 a protocol was signed with Sabena for the creation of a limited liability company to be named Air Congo. On 1961 the company was formed, and incorporated on 28 June with Sabena providing technical assistance and personnel. The Congolese government held a 65% percent stake, with Sabena holding 30%, and Air Brousse and Sobelair holding the balance. The initial fleet of Air Congo consisted of Douglas DC-3s, Douglas DC-4s and Douglas DC-6Bs; the first international destinations served by the carrier were Entebbe, Luanda, Nairobi, and Ndola. Sabena and Air Brousse continued their operations but these were ceased when Air Congo began operations on 21 June 1961. Whilst the airline was granted exclusive rights to operate scheduled domestic and international flights, it also received subsidies from the government in Léopoldville for any shortfall in loans which had been approved by the government.

...
Wikipedia