Due to the G20 Summit, Delhi airport is preparing for more than 250 daily aircraft cancellations :-

Flight operations at IGI Airport in New Delhi are expected to be disrupted. Due to the G20 Summit from September 7-10 potentially leading to the cancellation of up to 250 flights per day. The G20 Summit is planned to take place in the nation’s capital, which is anticipated to disrupt regular aircraft operations at Delhi’s Indira Gandhi International (IGI) Airport. Between September 7 and 10, operations will be hampered by the daily cancellation of around 250 flights.
Up to 250 flights per day may be canceled which could have a significant influence. On a large number of flights as a result throughout the course of these four days. There may be a possible impact on about 1,000 flights.