Vibrations from aircraft flying near the Qutub Minar in the national capital are damaging the 12th century minaret, the Archaeological Survey of India has said and asked the airport authority to immediately change the flight path.
The ASI last month wrote to the Airports Authority of India (AAI) to highlight how low flying aircraft could endanger the 72.5 metre red sandstone monument, one of the biggest tourist attractions in the city, and stated that a diversion in the flight route was imperative.
"The vibrations caused by the low flying aircraft near the monument is affecting the structure and we have asked the AAI to change the flying route immediately," BR Mani, ASI joint director general, told IANS.
According to Mani, the problem began in September 2008 after a new runway, the third at the airport, started functioning at the Indira Gandhi International Airport.
The 4.4-km runway is the longest in the country and capable of handling the largest aircraft category, which includes the Airbus A-380 and the Antonov An-225. With the new runway, the flight handling capacity of the airport has gone up to 65-70 flights an hour.
"After the new runway opened, the route for landing aircraft was shifted about 2.5 km away (towards Qutub Minar) from the approach route to the main runway," an airport official said.
"It (Qutab Minar) is an old monument and the low flying zone is very close to it; that causes repeated vibrations and can damage the monument," a senior archaeologist with the ASI added.
An official of the AAI, which manages airports across the country, said a study would be conducted if there was "anything to it".
"I don't know about this yet. But if there is anything then we will conduct the required study and look into it," V Somasundaram, AAI executive director, air traffic management, told IANS.
In January this year, historians had raised concerns that the monument, built by Qutubuddin Aibak in 1173, which already has a tilt of 25 inches to the southwest, is in danger of leaning further following rainwater seepage.
Acting quickly, the ASI cemented the area around the structure with lime to make it watertight. It also set up six underground water traps at a depth of 12 feet to prevent any water from reaching the 10-foot deep foundation of the structure.
According to some historians, Qutub Minar has a 'natural' tilt that occurred not when it was built, but was caused either when the two upper storeys of the monument were later being built or due to an earthquake.