Drukair operates into one of the world’s most challenging airports. Unpredictable weather, the high altitude of Paro Airport, surrounding mountains and the lack of navigational aids make good pilot training paramount for a safe operation.

The national airline of Bhutan is one of only two airlines that fly into the country’s sole international airport. The field is situated in a narrow valley at an altitude of 7,350 ft. The mountains nearby are up to 15,000 ft. high. The runway is 7,430 ft. long and 98 ft. wide. With only a VHF omnidirectional range (VOR) and distance measuring equipment (DME) in the vicinity of the airport, all approaches and departures have to be flown according to visual flight rules. There is no margin for error: The valley is so narrow that whenever an aircraft approaches for landing or is about to take off, the road along the airport fence is closed by police.

“You have to know the landmarks and you always have to have an escape plan,” says Sonam Tobgay, a senior training captain for Drukair.

In theory, landings and takeoffs are possible in both directions for what is designated Runway 33 and 15. But “we try to avoid this [15 approach] as much as possible;” says Tobgay. It is a very tricky maneuver. Aircraft attempting to land must fly over peaks around 13,000 ft. high in the immediate vicinity of the airport and then go for a circling approach into the Dupshare valley. There is no way to line up with the extended runway centerline early because there is a hill literally a few hundred feet northwest of the runway. “We have to level the wings, flare and reduce power at 50 ft. simultaneously,” Tobgay says. “It is real multitasking.”

The approach for Runway 33 is a little less challenging because there is more time to follow the curved valley down to the threshold and a few more seconds to align with the runway.

Takeoffs are equally tricky, particularly when provisioning for one-engine-out scenarios. An engine failure at takeoff from Runway 33 would be the worst case: “If you respect your procedures, you can make it,” says Tobgay. Respecting procedures here means going into takeoff-go-around mode immediately, retracting the gear, then following a visual departure path that is designed to gain as much altitude as possible. The problem with that takeoff is that there is no escape from the Dupshare valley, which is surrounded by mountains exceeding 16,000 ft. It is possible to make a turn back to the airport inside the valley, but only at a sufficient altitude.

Aircraft taking off toward the southwest have the advantage of being able to follow the valley with one engine out and then turn right, following another valley until it becomes wide enough for the turn at a lower altitude.

Because Paro is such a challenging airport, only captains are allowed to fly into and out of it. And they, too, have to go through extra training before they are approved for line operations. There is a special simulator for training to become familiar with the conditions, followed by the so-called valley checks. Any new captain has to fly 30 sectors under supervision.

But terrain alone is not the only issue in Paro. From February to May, it is essentially impossible to fly in the afternoon. Winds as strong as 80-90 kt. hit the mountains and cause severe turbulence during the valley approaches. Sometimes the wind does not even allow operations in the morning. Aircraft coming in from New Delhi or Bangkok often divert to Bagdogra in India “and wait it out,” as Tobgay says.