Europe's third largest budget carrier has warned that the global grounding since March of the Boeing 737 MAX aircraft, which make up 11% of Norwegian's fleet, may hamper its plans to return to profitability this year.

The company's yield, a measure of revenue per passenger carried and km flown, rose to 0.51 Norwegian crowns ($0.0572) in July from 0.45 crowns in June, lagging the 0.54 crowns expected by analysts in a Reuters poll.

Norwegian filled 93.5% of its available seats last month, up from 93.0% a year earlier but lagging an average analyst forecast of 93.8%.

Norwegian late last year announced plans to curb its rapid capacity growth and cut costs to preserve cash and stem losses from its operations. It has also raised 3 billion crowns from shareholders to boost its balance sheet.

The company's capacity expansion, as measured by available seat km (ASK), peaked at 51% growth year-on-year in June 2018 and has since declined, hitting 5% in July, slightly above the 4% percent that analysts had forecast.

Norwegian has sought to limit the impact from the grounding of its 18 MAX aircraft by combining flights, but the cost of renting replacement planes is still estimated at some 700 million crowns in 2019, it said last month.