When flights couldn't take off in Leh because air was too thin: Explained

All flights travelling in and out of Leh, Ladakh, were cancelled on Sunday due to an unprecedented weather event attributed to climate change. As it turns out, the flights were cancelled because they were incapable of operating due to a reduction in air density in the region.

Domestic carrier Indigo said on X (formerly Twitter), “All flights to/from Leh have been cancelled today due to weather conditions. We deeply regret the inconvenience caused.”

One of the passengers impacted by the flight disruptions was Chetan Singh Solanki, an IIT Bombay professor, also popularly known as the ‘solar man of India’. In a LinkedIn post, Solanki attributed the flight disruption to decreased air density in the region, which was caused by the unprecedented heat wave conditions in Leh.

Speaking to Business Standard, Solanki shared his experience and provided key insights into how air density can impact flight operations.

Expert explains how air density can impact flight operations

“On July 28, as I arrived at the airport to board my flight to Delhi, I completed the check-in process, cleared security, and settled near the boarding gate. The waiting area was crowded, with more people than chairs, leading some to sit on the floor. After a lengthy wait, I was taken aback by an announcement: numerous flights, including mine, were being cancelled. The reason behind these cancellations was even more astonishing,” he said.

He explained that flights were grounded due to unusually high temperatures, a surprising occurrence given that Leh is located at an altitude of 11,000 feet, where winters see temperatures plummet to -20°C.

“It seemed improbable that heat could disrupt flights in such a cold region. I later learned that this had also happened the day before.”

The technical explanation for these cancellations is that the air had become thinner or less dense, he explained. Air density refers to the concentration of air molecules within a given volume. At Leh's high altitude, the air pressure is naturally lower, which reduces air density. Additionally, the elevated temperatures contributed to a further decrease in air density. Although Leh is typically dry, any rise in temperature, even without increased humidity, causes the air to expand and thin out.

Thinner air means that aircraft engines must exert more effort to produce the necessary thrust and lift, as there are fewer air molecules available for intake and combustion. This increased demand for power can surpass the aircraft's capabilities, rendering it unsafe to operate in such conditions, the professor explained.

The Kushok Bakula Rimpochee Airport in Leh, one of the highest in the world, faces challenges due to mountain winds that necessitate flights taking off or landing in the morning hours. The air density also poses challenges for the Indian Air Force, impacting the load-bearing capacity of fighter aircraft and helicopters.

This phenomenon can also contribute to altitude sickness due to less oxygen availability, which is why it is recommended that tourists heading to high-altitude destinations such as Leh acclimatise to the environment before commencing their activities on the trip.