Changing wind pattern throws Delhi flight schedule at IGI airport haywire
More than 100 flights have been already diverted because of bad weather since April -- the highest diversion in summer season in the past one decade — because of inclement weather.delhi Updated: May 15, 2018 07:14 IST
A sudden change in the wind direction, from prevailing westerly winds to easterlies that come from the opposite direction bringing in moisture from the sea, over the past month, has taken a heavy toll on flight operations at the Indira Gandhi International airport in Delhi, meteorologists and airport officials said.
While more than 100 flights have been already diverted because of bad weather since April, on Sunday alone more than 78 flights had to be diverted — the highest diversion in summer season in the past one decade — because of inclement weather.
“The diversion we are witnessing this year because of wind shear is unique. Such diversions are usually witnessed during fog days,” said an official at Delhi airport who asked not to be identified because he is not authorised to speak to the media.
Scientists of India Meteorological Department’s centre at IGI airport said one of the primary reasons behind this is the changing wind pattern.
While Delhi usually sees westerly and north westerly winds during this time of the year (April-May), this year, the dominant winds are moisture laden ones from the easterly and south-easterly direction.
“The intense heat across northwest India and the moisture is helping in the formation of more dust storms and cumulonimbus clouds and thunderclouds. Even though flights are not affected by rain, thunderstorms take a heavy toll on them because of the down burst and micro burst associated with them,” said RK Jenamani, head of the aviation meteorology services of Delhi region and IGI Airport. Down bursts are powerful, localised columns of wind that occur when cooled air drops from the base of a thunderstorm at incredible speeds — up to 60 mph — and subsequently hits the ground, spreading out in all directions.
Runways in airports are built in such a way that they are aligned with the prevailing wind conditions. It is because during take off and touchdown flights need winds from the opposite direction. While cruising, the aircraft ideally needs a tail wind.
“Usually westerly and north westerly winds prevail over Delhi as a result of which flights take off accordingly. But as this time easterly and south easterly winds are dominating, flights are being forced to change their take off and touchdown routes. This is taking more time and could also end up in burning more fuel,” added Jenamani.
Such weather events decrease the capacity of runways by nearly 20- 25% official said. Delhi, on average, sees around eight such events (including minor thunderstorms) in May, but has already seen five till May 13 leading to a large number of flight diversions.
The International Civil Aviation Organization’s 2016 environmental report warned that changes to the atmosphere, brought about by rising global temperatures caused by greenhouse gas emissions, would affect airplane’s ability to fly, while rising sea levels would affect airports. It said that impacts would include higher-speed winds impeding the ability of aircraft to take off and an increase in flight turbulence, instances of icing (formation of ice on surface of the aircraft), and engine-threatening dust storms.
Whether these recent events are results of global warming and climate change are yet to be ascertained, but scientists have warned that increasing temperatures could result in more dust storms both in terms of frequency and intensity across northwest India.
“It is possible that global warming is contributing to the increase in the thunderstorms over northwest India. During April-May, the land over northern India gets heated up and this heating results in “thermal lows”, where the surface pressure is less compared to less heated surrounding regions. These thermal lows are responsible for thunder storms and dust storms during the pre-monsoon months. As the global surface temperature increases, the thermal lows can also strengthen and result in stronger storm events. The increased surface warming would lead to more evaporation which in turn can result in stronger rain events,” said Sandeep Sukumaran, an assistant professor at Centre for Atmospheric Sciences at IIT Delhi who specialises in climate modelling.