"We have had a significant number of flight cancellations and delays in the past few days due to various reasons including crew unavailability," a company spokesperson said in a statement.
Vistara, owned by Tata Group and Singapore Airlines, is using its larger aircraft, including the wide-body Boeing 787 Dreamliner even on certain domestic routes "to accommodate more passengers, wherever possible," an airline spokesperson told the media.
The airline, which will be merged with Tata-owned Air India, faced similar disruptions last month.
According to reports, a significant number of pilots have taken sick lives resulting in the shortage.
As per the airline company besides the absence of the pilots, they have to also deal with unforeseen maintenance needs.
The airline has also offered refunds to passengers.