More than half of the planned decarbonization of aviation was dependent on the development of sustainable aviation fuels, which has reached only 0.8% of airline fuel needs this year.

The XLR delays would represent another hurdle for IndiGo’s ambitious international expansion, which is under pressure from soaring jet-fuel costs and airspace restrictions.

Passengers had not yet boarded, but two Lufthansa cabin crew members and an unspecified number of service workers who were on board sustained minor injuries.