The Globe and Mail reports in its Wednesday edition that United Airlines raised questions over the fate of billions of dollars of 737 Max 10 jets on order from Boeing, piling pressure on the plane maker. A Reuters dispatch to The Globe says that United Airlines chief executive Scott Kirby on Tuesday said the airline, which has ordered 277 of the Max 10 jets with options for another 200, would build a new fleet plan that does not include a model already mired in regulatory and delivery delays. U.S. regulators have grounded most of Boeing's Max 9 jets for checks after a plug replacing an unused exit door tore off an Alaska Airlines jet on Jan. 5, forcing an emergency landing. Industry watchers have been looking for concrete signs that Boeing's woes with the Max 9 and the legacy of earlier Max safety groundings are undermining support for the larger Max 10, which makes up more than a fifth of outstanding Max orders. "I think the Max 9 grounding is probably the straw that broke the camel's back for us," Mr. Kirby told CNBC on Tuesday. The Max 10 does not have the same kind of door-plug system as the Max 9, but the grounding has raised concerns that the incident could delay regulatory approval and delivery of the Max 10.