25 October 1919
Air services were inaugurated in South Africa with the amalgamation of a London-based company, the South African Aerial Navigation Company and the SA-based South African Aerial Transports Ltd company, under the name of the latter. The headquarters of the service was at Barangwanath airport, near Johannesburg. The company aimed to convince the public of the feasibility and safety of commercial aviation and to secure a Government subsidy. However, it was only in 1929 that a government subsidy was secured. That enabled Maj. Allister Miller, since 1919 the driving-force behind SA aviation, to start the first official commercial air services under the name of Union Airways Company (Pty.) Ltd, introducing a regular service between Port Elizabeth, Johannesburg, Cape Town and Durban.  
References

Potgieter, D.J. et al. (eds)(1970). Standard Encyclopaedia of Southern Africa, Cape Town: NASOU, v. 1, p. 612.