The airport and airline sources said runway 11/29 will be shut for three days from November 7 for maintenance work.
Delhi International Airport Ltd (DIAL), which operates the aerodrome, has already communicated the decision to the airlines, which are now working on ways to minimise the inconvenience to passengers, the airline sources added.
According to them, there would be curtailment of operations and many flights would have to be rescheduled. There could also be cancellations and various options are being worked out, they added.
One of the airline sources said bigger aircraft might be pressed into service to accommodate the passengers.
Queries sent to DIAL about the proposed shutting of one runway did not elicit any response.
In 2016-17, the airport handled 57.7 million passengers and more than 8.57 lakh tonnes of cargo.
DIAL is a consortium led by the GMR group. Other stakeholders are the government-owned Airports Authority of India (AAI) and Germany's Fraport.