IndiGo Airlines (6E, Delhi Int'l) has lifted the altitude restriction on its troubled A320neo fleet following advice from engine manufacturer Pratt & Whitney that it was not necessary.

India's Business Standard has viewed a notification from airline management to pilots which says: "From September 1, planning of cruising flight levels will be as earlier on performance, environmental and other common factors irrespective of the engine type IAE, CFM or NEO up to Airbus limits as per flight command."

IndiGo pilots were advised in May 2017 to observe a maximum altitude of 30,000 feet whenever practicable in a bid to reduce known problems with the bearings of the PW1100G geared turbofans. However, Pratt & Whitney have now advised that normal flight operations can recommence.

"This recommendation was intended to address component durability related to the No 3 seal. Since March, new engines and overhauled engines have incorporated improvements that have enhanced the engine's durability," a P&W spokesperson said.

IndiGo currently operates twenty-three A320-200neo aircraft, of which four are inactive, and has a total of more than 400 on order with Airbus.