Complex sentence: On 24 April 1994, South African Express (SA Express), a feeder airline service of South African, began operating after a 3-year preparation process begun in 1991, when the regional airline was granted its operating license.
Split into simpler sentences: On 24 April 1994, South African Express (SA Express), a feeder airline service of South African, began operating. This came after a 3-year preparation process since 1991, when the regional airline was granted its operating license.