20 April 1968
Pretoria, a Boeing 707 of South African Airways (SAA), en route to London and only in use for seventeen days, crashed and exploded shortly after take-off from Windhoek airport. Of the 129 people on board, 122 were killed. 
References

Potgieter, D.J. et al. (eds)(1970). Standard Encyclopaedia of Southern Africa, Cape Town: NASOU, v. 1, p. 257.|Wallis, F. (2000). Nuusdagboek: feite en fratse oor 1000 jaar, Kaapstad: Human & Rousseau.|https://66.249.93.104/search?q=cache:OBbC01pvN5oJ:|www.caa.co.za/publications_files/Safety%2520Link/Safetylink.june.pdf+The+Boeing+707+ Pretoria+crashes+in+Windhoek&hl=en&gl=za&ct=clnk&cd=2