Turbulent times in the air

In the past few months, there have been serious inflight air turbulence incidents, notably involving a Singapore Airlines flight over Burma and an Air Europa flight over Brazil.

There was one fatality and many injuries, and both flights had to make emergency landings. These and other air turbulence incidents have made international headlines, and videos of severe shaking in the cabin shared by passengers have gone viral.

This means passengers are more aware of the need to keep seat belts fastened, and airlines have also tightened rules about in-flight service while the seat belt signs are on. Some carriers have made it mandatory for passengers to be seated with belts fastened 30 minutes before landing.

With climate breakdown heating up the atmosphere, not only are there more severe storms but also clear air turbulence (CAT) that can hit without warning. A scientific study by the University of Reading calculated that CAT was 55% more frequent in 2020 compared to 1979.

Flying in Nepal has always been more prone to air turbulence because of the combination of wind, weather and high terrain. Also domestic flights in Nepal involve smaller turboprop aircraft like the ATR 72 or the Bombardier Q400 which tend to be bounced around more.

“Passengers need to understand that although it feels scary, there is nothing to worry about as long as they have their seat belts on,” says  Menit KC, a pilot with Buddha Air. “Modern aircraft are meticulously designed and tested to handle turbulence. It is like driving a car on a bumpy road.”

The problem with CAT as compared with cumulus cells is that they are visible neither to the pilots nor on weather radar in the cockpits, and can hit without warning. Pilots therefore rely on information from other planes flying the same route about turbulence ahead. Some international airlines have now also installed sophisticated cockpit instruments that can detect CAT ahead.

The most air turbulence in flights over Nepal occurs during the pre-monsoon afternoons when there are a lot of thunderstorm cells. These are visible on cockpit weather radar as red splotches, and pilots simply fly around them. 

During the monsoon, although the sky is overcast and there is a lot of rain,  flying into clouds is not as bumpy. CAT danger is higher in winter in Nepal because of the westerly jetstream.

Turbulence is more common when flying in terrain like Nepal where even on cloudless days prevailing winds are lifted by one side of the mountains, and there are downdrafts on the other side. There are also katabatic winds that pilots are aware of, and steer their aircraft well clear of such zones.

“When we see weather ahead on the radar, we go around it to avoid it,” says pilot KC. “In case of CAT, we ask permission from the ATC to descend to a lower altitude to reduce its severity.”

Another kind of turbulence is called ‘wake turbulence’ which can be encountered by smaller aircraft when there is a ‘heavy’ plane flying ahead — usually during take off or landing. 

Because Nepal’s domestic flights are mostly short and passengers do not need to go to the restroom, it is a good idea to keep seat belts fastened at all times. 

Buddha Air’s ATR 72 are sturdy planes with 1,400 of them flying around the world. They also have state-of-the-art avionics that help pilots navigate around areas of turbulence. 

Says pilot Menit KC: “Before every flight we get a briefing about weather en route and destination airports, and we are trained to handle en route turbulence. Sosit back, relax and enjoy your flight.”