Royal Nepal 409 to Hong Kong was just airborne from Kathmandu Thursday morning at 9:48 when Captain GP Rijal noticed the digital navigation instruments on the 757's cockpit were not working properly. He kept the plane on a standard departure climb, but immediately realised to his horror that the navigation screen had gone blank.

Climbing through 11,500ft, the plane soon entered cloud and the pilot radioed he was coming back, even though Kathmandu was overcast with low cloud ceiling. On the ground, in the darkened interior of the airport's radar control room, Ananda Mool and Narendra Sayami watched RA409's blip on the screen as it circled at 19,000ft over Kathmandu.

How to bring the plane down when the pilots didn't know where they were? Capt Rijal took the plane south, and asked radar to talk him down. Over the next 15 minutes, Mool and Sayami gave precise instructions to the 757 on bearing and altitude so the plane could descend into Kathmandu, avoiding the high mountains. Suddenly, RA409 came on: "Ok, we are now VFR." The 757 had finally broken through clouds at 10,000ft above Kathmandu, and made a steep descent to land safely.

"All thanks go to the radar operators, it was very professionally handled, we were like a crow in fog," an ecstatic Rijal told us after landing (see pic). The civil aviation authorities are investigating the incident, and they will want to know why the failsafe standby systems on the 15-year-old 757's on-board navigation computers did not work.