US Airways and one of its major creditors have agreed to extend by two weeks the deadline for the carrier to file a reorganization plan with the bankruptcy court. The airline was scheduled to file that plan today, but General Electric Co., which holds a stake in many of US Airways' planes and engines, agreed to give the airline until the end of April, the companies said in a statement Thursday.It is the third extension GE has granted US Airways, which is trying to emerge from bankruptcy protection. If the airline fails to file a plan "reasonably acceptable" to GE, the creditor could seek repayment, likely triggering a shutdown.