IndiGo and Go Airlines Ltd-run GoAir, among to first to fly the new Airbus A320neo, have been forced to find ways to deal with vexing technical snags with the Pratt & Whitney engines that power the aircraft. IndiGo has asked its pilots to fly snag-hit A320neo planes at a lower altitude, 30,000 feet, and not the usual 36,000 feet, to reduce strain on engines.