Authorities in Nepal have suspended three air traffic controllers and launched an investigation after two planes about to land at Kathmandu’s international airport nearly collided, AFP reported.

The incident happened on Friday. The Air India plane, which was waiting at an altitude of 5,800 meters for landing clearance, suddenly descended and was about to collide with a Nepal Airlines plane, which was flying at an altitude of 4,572 meters.

“The three air traffic controllers who were on duty at the time have been suspended from duty until further notice,” said Jagannath Nirula, a spokesman for the Civil Aviation Authority of Nepal.

A commission of inquiry was set up to investigate the possible error of the Air India pilot and a letter was sent to the Indian authorities.

Poor equipment maintenance and lax compliance with safety regulations plague Nepal’s air transport sector, despite international guidelines. The European Union has banned all Nepalese carriers from entering its airspace for security reasons.