The failure of control-tower equipment at OR Tambo International Airport left dozens of planes grounded and thousands of passengers frustrated on Wednesday.

The problems slowed international and local arrivals and departures at Africa’s busiest airport to a snail’s pace.

Airline companies warned that there would be a huge knock-on effect on flights leaving and arriving in Johannesburg.

The radio technology problems arose as South Africa’s leading civil aviation safety and security experts met in Johannesburg for a safety and security conference on Wednesday.