Following are airlines that have warned of the potential cost of the grounding:

TUI

March 29: TUI expects underlying earnings before interest, tax and amortization (EBITA) to fall by 17 percent, having previously expected the figure to be on a par with the 1.18 billion euros generated in 2018.

It added that EBITA could even fall as much as 26 percent in 2019 if the planes remain grounded beyond the middle of July.

SOUTHWEST AIRLINES

March 27: Southwest Airlines Co cut its financial outlook for the year after being forced to pull its new fleet of 34 Boeing 737 MAX planes out of service.

The Dallas, Texas-based airline, which has also struggled with maintenance problems and a harsh U.S. winter, estimates it will have canceled 9,400 flights between mid-February and March 31, reducing growth in its number of available seats to just 1 percent compared to a year ago.

Overall it estimated it would lose $150 million in revenue in the quarter compared to previous expectations.

WESTJET

March 18: The Canadian carrier suspended its 2019 financial projections following the groundings.

AIR CANADA

March 15: Air Canada suspended its 2019 financial forecasts, saying it continued to adapt a contingency plan to address the uncertainty surrounding the planes.

UNITED AIRLINES

March 15: United Airlines, the No. 3 U.S. carrier, said it would see an adverse effect on its operations if the jets remained grounded heading into the peak summer travel season.

(Editing by Keith Weir)