**Exhibit 31.1**

Certification ofthe Principal Executive OfficerPursuant to 15 U.S.C. 78m(a) or 78o(d)(Section 302 of the Sarbanes-Oxley Act of 2002)

I, Glenn F. Tilton,certify that:

(1)          I have reviewed thisquarterly report on Form 10-Q for the period ended March 31,2007 of United Air Lines, Inc. (the “Company”);

(2)          Based on my knowledge,this report does not contain any untrue statement of a material fact or omit tostate a material fact necessary to make the statements made, in light of thecircumstances under which such statements were made, not misleading withrespect to the period covered by this report;

(3)          Based on my knowledge,the financial statements, and other financial information included in thisreport, fairly present in all material respects the financial condition,results of operations and cash flows of the Company as of, and for, the periodspresented in this report;

(4)          The Company’s othercertifying officer and I are responsible for establishing and maintainingdisclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and15d-15(e)) and internal control over financial reporting (as defined inExchange Act Rules 13a-15(f) and 15d-15(f)) for the Company andhave:

(a)          Designed such disclosurecontrols and procedures, or caused such disclosure controls and procedures tobe designed under our supervision, to ensure that material information relatingto the Company, including its consolidated subsidiaries, is made known to us byothers within those entities, particularly during the period in which thisreport is being prepared;

(b)         Designed such internalcontrol over financial reporting, or caused such internal control overfinancial reporting to be designed under our supervision, to provide reasonableassurance regarding the reliability of financial reporting and the preparationof financial statements for external purposes in accordance with generallyaccepted accounting principles;

(c)          Evaluated theeffectiveness of the Company’s disclosure controls and procedures and presentedin this report our conclusions about the effectiveness of the disclosurecontrols and procedures, as of the end of the period covered by this reportbased on such evaluation; and

(d)         Disclosed in this reportany change in the Company’s internal control over financial reporting thatoccurred during the Company’s most recent fiscal quarter that has materiallyaffected, or is reasonably likely to materially affect, the Company’s internalcontrol over financial reporting; and

(5)          The Company’s othercertifying officer and I have disclosed, based on our most recent evaluation ofinternal control over financial reporting, to the Company’s auditors and theaudit committee of Company’s board of directors (or persons performing theequivalent functions):

(a)          All significantdeficiencies and material weaknesses in the design or operation of internalcontrol over financial reporting which are reasonably likely to adverselyaffect the Company’s ability to record, process, summarize and report financialinformation; and

(b)         Anyfraud, whether or not material, that involves management or other employees whohave a significant role in the Company’s internal control over financialreporting.
| /s/ Glenn F. Tilton      |   |
|--------------------------|--------|
| Glenn F. Tilton          |   |
| Chairman,  President and |   |
| Chief Executive  Officer |   |
| Date:  May 15, 2007 |   |

 

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