Exhibit 5.1
                                                                     -----------

                                                                   March 1, 1995


Securities and Exchange Commission
450 Fifth Avenue, N.W.
Washington, D.C. 20549

    Re:  Registration Statement on Form S-4
         (File No. 33-57579)

Ladies and Gentlemen:

    I am Vice President-Law and Corporate Secretary of UAL Corporation, a 
Delaware corporation (the "Company"), and am familiar with the proceedings taken
and to be taken by the Company (the "Corporate Proceedings") in connection with 
the Registration Statement on Form S-4 (File No. 33-57579) (the "Registration 
Statement"), that the Company has filed under the Securities Act of 1933, as 
amended (the "Securities Act"), relating to the offer to exchange for the 
Company's outstanding shares of Series A Convertible Preferred Stock (the 
"Series A Preferred Stock") the Company's 6-3/8% Convertible Subordinated 
Debentures due 2025 (the "Debentures") to be issued pursuant to an indenture
(the "Indenture") to be dated as of April 3, 1995 between the Company and The
Bank of New York, as trustee.

    This opinion is delivered in accordance with the requirements of Item 
601(b)(5) of Regulation S-K promulgated under the Securities Act.

    In connection with this opinion, I or attorneys under my supervision have 
examined or are familiar with originals or copies of (i) the Restated 
Certificate of Incorporation and By-laws of the Company, (ii) resolutions of the
Board of Directors, (iii) the Registration Statement, (iv) the Rights Agreement 
dated as of December 11, 1986, as amended, between the Company and First Chicago
Trust Company of New York, as Rights Agent (the "Rights Agreement"), which 
provides for one right (the "Right") to purchase shares of the Company's Series 
C Junior Participating Preferred Stock to be attached to and issued with each 
share of the Company's common stock, $.01 par value (the "Common Stock"), and 
(v) such other documents as I have deemed necessary or appropriate as a basis 
for the opinions set forth below.

    Based upon and subject to the foregoing, I am of the opinion that upon 
completion of the Corporate Proceedings:

 
  1.  The Debentures will have been duly authorized for issuance and, when the 
Indenture has been duly executed and delivered by the parties thereto and when 
the Debentures are duly executed, authenticated, issued and delivered in 
exchange for the shares of Series A Preferred Stock as contemplated by the 
Registration Statement, the Debentures will constitute valid and legally binding
obligations of the Company entitled to the benefits of the Indenture, subject to
bankruptcy, insolvency, reorganization, moratorium and similar laws of general 
applicability relating to or affecting creditors' rights and to general equity 
principles (whether considered in a proceeding at law or in equity) and the laws
of fraudulent conveyance.

  2.  The Common Stock to be issued upon conversion of the Debentures, when 
issued in accordance with the terms of the Debentures, will be validly issued, 
fully paid and nonassessable.

  3.  The Rights, when issued in accordance with the Rights Agreement, will be 
validly issued.

  I hereby consent to the filing of this opinion with the Securities and 
Exchange Commission as an exhibit to the Registration Statement.


                                       Very truly yours,

                                       /s/  FRANCESCA M. MAHER

                                       Francesca M. Maher
                                       Vice President-Law and
                                         Corporate Secretary