Major U.S. airlines sought a government bailout of more than $50 billion as the White House is urgently drafting a financial assistance package in the wake of the steep falloff in U.S. travel demand sparked by the coronavirus pandemic.A trade association warned that without action airlines could run out of money by year-end - and even sooner if credit card companies started withholding payments. Without action soon, airlines and others in the sector could furlough tens of thousands of workers.