17 January 1996
The South African government approved the Constitution of the African Civil Aviation Commission (AFCAC) on 17 January 1996, deposited its Instrument of Ratification on 8 March 1996. AFCAC was established on 15 June 1947 and its constitution, signed on 17 January 1969, only came into effect on 15 March 1972. South Africa joined in September 1994 but the country took a little more time before ratifying the constitution. AFCAC is a specialised and independent body of the Organisation of African Unity (now the African Union) which aims to encourage co-operation in all civil aviation activities in Africa.  Furthermore, the body aims to formulate plans at the regional and sub-regional levels for the provision of air services within and outside Africa. Membership to AFCAC is open to African States and members of African Union. 
References

Anon, 'Constitution of the African Civil Aviation Commission', from Organisation of African Union (OAU), [online] Available at www.africa-union.org [Accessed: 13 January 2011] Anon, 'Organization of African Unity (OAU) / African Union (AU)' from The Department of International Relations and Cooporations, Republic of South Africa, 12 February 2004 [online] Available at www.dfa.gov.za [Accessed: 13 January 2011]