here's marissa parra. >> reporter: summer travel is expected to soar to record highs. but a potential shortage of planes looms on the horizon. >> that's leaving airlines really bracing to make sure that they can handle that onrush of travel demand. >> reporter: u.s. airlines this year expected to receive 40% fewer planes than they planned for last year according to industry group aerodynamic advisory, which means one thing for your travel budget. >> from a consumer standpoint, with demand strong and supply relatively weak, that's a recipe for higher airfares. >> reporter: united airlines and southwest pausing hiring. united even offering their pilots unpaid leave. alaska airlines along with southwest unsure how many flights they can fly, calling their capacity forecast uncertain. all of the airlines pointing directly to boeing's 737 max production delays. the aviation giant facing quality control scrutiny and under