However, all international flights, including the long-haul ones to places like London, New York, Toronto and Chicago, were on schedule, an Air India spokesperson told PTI.
But confusion prevailed at the airport here with large number of passengers queueing up at Air India counters to find the status of their flights as several domestic flights were delayed and some others combined.
The agitating pilots reported for duty but said they were under stress due to the financial problems and, therefore, unable to undertake flight duties, airline sources said, as the pilots' union, Indian Commercial Pilots Association (ICPA), appealed to the agitators to return to work.
Top ICPA leaders met the airline management in Delhi, where 22 pilots reported being "under stress" and not undertaking flight duties.
Protesting non-payment of their salary and allowances, a section of Air India pilots had yesterday decided to go on "no-pay-no-work" agitation from midnight last night. The pilots claimed that flying allowances, which constitute 80 per cent of their salary, were not being paid since last August.
Reacting to the agitation, Civil Aviation Minister Ajit Singh said, "They (pilots) have not sent a notice but some have reported sick. Some disruption is there in Delhi but nothing has happened anywhere else. The employees have a problem, they have not been paid for one-two months. Allowances have not been paid for quite a few months now.
"We understand their problem but Air India's finances are in a bad condition. Their accounts were frozen yesterday."
Flight operations of Air India were disrupted on Saturday after 40 of its pilots reported sick as part of their 'work to rule' stir against the management's failure to pay allowances, with the government saying it will take steps to resolve the issue.