Kathmandu — Nepal on Tuesday tightened flight permit rules for airlines by making it mandatory to have clear weather throughout the route, after a preliminary investigation indicated that bad weather was the main cause of Sunday’s plane crash in the Himalayan nation’s mountainous Mustang district that killed all 22 people on board.

So far, Nepal’s aviation regulator, the Civil Aviation Authority of Nepal (CAAN), has been issuing permits to airlines if weather conditions at the source and destination airports are okay. But, from now onwards, the en-route weather conditions of the flight will also be looked into.

Nepal being a mountainous country, the weather condition is always fluctuating and it is difficult to operate a flight in the mountain region without proper weather forecasting mechanism.

The new provision is applicable to all flights following the Visual Flight Rules.

While submitting the flight plan, the airlines are required to submit weather forecasting information acquired from the Department of Hydrology and Meteorology regarding the weather of the flight destination and en route, according to the notice issued by CAAN.

A preliminary investigation revealed that the Canadian-built turboprop Twin Otter 9N-AET plane of Tara Air had crashed into the mountains after it swerved to the right, instead of turning to the left due to inclement weather.

The Canadian-built turboprop Twin Otter 9N-AET plane was carrying four Indians, two Germans and 13 Nepali passengers, besides a three-member Nepali crew when it crashed minutes after taking off from the tourist city of Pokhara on Sunday.

The government has formed a five-member commission of inquiry headed by senior aeronautical engineer Ratish Chandra Lal Suman to find out the cause of the Tara Air plane crash that killed 22 people, including four Indians and two Germans.

Nepal, a country often referred to as one of the world’s riskiest places to fly, has had a fraught record of aviation accidents, partly due to its sudden weather changes and airstrips located in mountainous terrain.

Fickle weather patterns are not the only problem for flight operations in Nepal. According to a 2019 safety report from CAAN, Nepal’s “hostile topography” is also part of the “huge challenge” faced by pilots.

In 2016, all 23 people aboard were killed when a plane of the same airline flying the same route crashed after takeoff.

In March 2018, a US-Bangla Air crash occurred at the Tribhuvan International Airport, killing 51 people on board.

A Sita Air flight crashed in September 2012 while making an emergency landing at the Tribhuvan International Airport, killing 19 people.

A plane flying from Pokhara to Jomsom crashed near Jomsom airport on May 14, 2012, killing 15 people. (PTI )