Exhibit 21 UAL CORPORATION SUBSIDIARIES Subsidiary Place of Incorporation Business Name Air Wis Services, Inc. Wisconsin Air Wis Services, Inc. Four Star Insurance Bermuda Four Star Insurance Company, Ltd. Company, Ltd. Mileage Plus, Inc. Delaware Mileage Plus, Inc. UAL Leasing Corporation Delaware UAL Leasing Corporation U-C Corp. Delaware U-C Corp. United Air Lines, Inc. Delaware United Air Lines, Inc.