The US Federal Aviation Administration (FAA) has banned foreign pilots from making visual approaches to San Francisco airport runways 28 left and right.
The move follows the crash of a Asiana Airlines Boeing 777-200ER that killed three people on 6 July, a low approach by an Eva Air 777-300ER on 23 July that prompted a go-around command by the airport tower, and several missed approaches by pilots of foreign airlines since 1 June.
In all of the recent incidents, the foreign pilots were making visual approaches to Runway 28 left or right. The glideslope indicator that enables a stabilised approach to the runways has been deactivated since 1 June, forcing pilots making certain approaches to fly the aircraft visually.
"Until that [stabilised] approach is again available in late August, the FAA is assigning alternate instrument approaches to all foreign carriers," the agency says. "The FAA took this action after noticing an increase in go-arounds at [San Francisco airport] by some foreign carriers that were flying visual approaches into the airport."
The probable cause of the Asiana 777 crash remains under investigation by the National Transportation Safety Board. It is known that the crew failed to keep the aircraft on the proper glidepath, coming in too low and slow and clipping the main landing gear on the seawall at the runway threshold.
The Eva 777 flight crew also was flying a visual approach on 23 July when the tower directed the crew to fly a go-around. The air traffic controller alerted the pilots that they were approaching the runway at a "lower than normal altitude", the FAA says.
"Go-arounds are important safety tools for both pilot sand air traffic controllers", the FAA says. "They are routine, standardised procedures and can occur once a day or more at busy airports for various reasons."
The glideslope indicator on Runway is deactivated until late August for the airport to complete a construction project at the other end of the runway. The construction is part of the FAA's runway safety area improvement programme.
Read more expert analysis by David Learmount of aircraft accidents and incidents on his eponymous blog