Budget carriers IndiGo and GoAir have cancelled more than 600 flights scheduled over the next few days after the Directorate General of Civil Aviation grounded A320 neo planes that ran on faulty Pratt & Whitney engines, PTI reported on Friday. IndiGo has cancelled 488 flights between March 15 and March 31 while GoAir has suspended 138 flights between March 15 and March 22.

The two companies have 45 A320 neo planes with Pratt & Whitney engines, out of which 14 have been grounded. The Directorate General of Civil Aviation has asked both the airlines not to refit these engines with spare parts in their inventory. The regulator has said it will make further decisions on the matter after consulting with the European Aviation Safety Agency and engine manufacturer.

The two airlines together operate more than 1,200 flights daily. The cancellations are likely to affect an estimated 1 lakh passengers if the passenger load factor of both these airlines in January are taken into account, The Times of India reported. The airlines, however, did not say how they would compensate or provide alternative choices to passengers who have already booked their tickets.

The impact of cancellations is expected to be more severe in April, with the start of the summer schedule. It has already had a ripple effect on flight fares, with fares for Mumbai-Delhi flights increasing three-fold.

“We follow the process as specified by DGCA in its CAR [Civil Aviation Requirement],” an unidentified GoAir spokesperson told PTI. “The same has also been published on our website.”