11 September, 2011 - The department of civil aviation (DCA) has not yet approved the national airline’s ATR aircraft from performing test flights at Yonphula airstrip in Trashigang.
DCA director general, Phala Dorji said outside experts have been called in to study whether the ATR 42-500 can safely be operated to Yonphula, and Batpalathang airstrip in Bumthang.
The study will focus on the runway lengths of the two airstrips, and the take off and landing lengths required by the ATR aircraft. The runway length for Batpalathang and Yonphula are 1,200m and 1,300m respectively.
Calculating take off and landing lengths requires a number of factors to be taken into consideration, such as altitude, weight of aircraft, temperature, wind speed and direction, among others.
According to information on the ATR manufacturer’s website, the aircraft with a full load of 48 passengers, each weighing 95kg, will require 990m to take off at sea level. This required length increases as airport altitude increases. For instance, at 3,000ft and take off under same weight increases to 1,163m, according to the manufacturer. The same concept applies to landing length required.
With both Batpalathang and Yonphula situated at around 8,500ft, the ATR will have to operate by carrying less than full capacity to safely operate within the two airstrip’s runway lengths. This means flying with less passengers.
This practice, referred to as weight penalty in aviation terms, is also used at Paro airport for any kind of aircraft.
DCA will base its approval on the results of the study conducted by foreign expertise. Phala Dorji said the agency would have to be thoroughly “convinced” prior to approving any test flights.
Drukair CEO Tandin Jamso said the airline is confident of the ATR’s ability to handle the country’s domestic airstrips. He pointed out that ATR officials, who will perform the first test flights, were also confident that the aircraft would safely operate on both airstrips. He added that, if there were risk, the manufacturer itself would not conduct such an activity, as it would hurt their reputation.
He added that no airline would invest in equipment if it would not be able to perform at airports or airstrips it would eventually be using.
Meanwhile, DCA has also instructed Drukair to store spare parts to prevent lengthy groundings of its ATR. The length of the groundings was primarily due to transportation of spare parts from abroad. The aircraft was grounded almost the entire month in August.
According to DCA, the three consecutive technical problems were not major safety issues. DCA reiterated that the 9-year-old ATR aircraft had passed audit inspections prior to purchase by Drukair and is in good condition.
By Gyalsten K Dorji
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