Two men were killed on Wednesday when their two-seater aircraft crashed near Hekpoort, north-west of Krugersdorp, Gauteng police said.
Inspector Odette van Staden said the aircraft fell out of the sky at about 5pm on Wednesday.
Witnesses said that the aircraft went into a spiral before crashing to the ground.
The South African Civil Aviation Authority expressed concern earlier on Wednesday over the recent spate of fatal aircraft accidents.
Commissioner for civil aviation, Captain Colin Jordaan, said that since October 1, 12 accidents occurred, of which seven had resulted in 23 fatalities.
The Hekpoort crash brought to 25 the number of deaths due to aircraft accidents in one month.
The causes of the accidents were under investigation. — Sapa