UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  SCHEDULE 13G
                                 (Rule 13d-102)

             INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT
           TO RULES 13d-1(b), (c) AND (d) AND AMENDMENTS THERETO FILED
                            PURSUANT TO RULE 13d-2(b)
                               (Amendment No. 2)*

                                 UAL Corporation
                                (Name of Issuer)

                   Common Stock, with $.01 par value per share
                         (Title of Class of Securities)

                                    902549807
                                 (CUSIP Number)

                               December 31 , 2007
             (Date of Event which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule
is filed:

      [X]     Rule 13d-1(b)

      [ ]     Rule 13d-1(c)

      [ ]     Rule 13d-1(d)

*The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter the
disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 or otherwise subject to the liabilities of that section of the Act but
shall be subject to all other provisions of the Act (however, see the Notes).

<PAGE>
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CUSIP No. 902549807                 13G                        Page 2 of 5 Pages
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--------------------------------------------------------------------------------
1.    NAMES OF REPORTING PERSONS
      I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

      Impala Asset Management LLC

      41-2118667
--------------------------------------------------------------------------------
2.    CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions)
                                                                         (a)[ ]
                                                                         (b)[X]
--------------------------------------------------------------------------------
3.    SEC USE ONLY


--------------------------------------------------------------------------------
4.    CITIZENSHIP OR PLACE OF ORGANIZATION

      State of Delaware
--------------------------------------------------------------------------------
              5.     SOLE VOTING POWER
                     0

  NUMBER OF   ------------------------------------------------------------------
   SHARES     6.     SHARED VOTING POWER                                        
BENEFICIALLY         12,284,199                                                 
  OWNED BY                                                                      
    EACH      ------------------------------------------------------------------
  REPORTING   7.     SOLE DISPOSITIVE POWER                                     
   PERSON            0                                                          
    WITH                                                                        
              ------------------------------------------------------------------
              8.     SHARED DISPOSITIVE POWER                                   
                     12,284,199                                                 

--------------------------------------------------------------------------------
9.    AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
      12,284,199

--------------------------------------------------------------------------------
10.   CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (See
      Instructions)
                                                                            [ ]
--------------------------------------------------------------------------------
11.   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

      10.56%
--------------------------------------------------------------------------------
12.   TYPE OF REPORTING PERSON (See Instructions)

      IA
--------------------------------------------------------------------------------

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CUSIP No. 902549807                 13G                        Page 3 of 5 Pages
------------------------                                       -----------------


Item 1(a).         Name of Issuer.
                   UAL Corporation

Item 1(b).         Address of Issuer's Principal Executive Offices.

                   77 W. Wacker
                   Chicago, IL 600601

Item 2(a).-(c).    Names of Person Filing.

                   Impala Asset Management LLC
                   134 Main Street
                   New Caanan, CT 06840

                   Citizenship. Delaware

Item 2(d).         Title of Class of Securities.
                   Common Shares with $.01 par value per share

Item 2(e).         CUSIP Number.  902549807

Item 3.     If This Statement is Filed Pursuant to Rule 13d-1(b), or 13d-2(b) or
            (c), Check Whether the Person Filing is a:

    (a) [ ] Broker or dealer registered under Section 15 of the Exchange Act.

    (b) [ ] Bank as defined in Section 3(a)(6) of the Exchange Act.

    (c) [ ] Insurance company as defined in Section 3(a)(19) of the Exchange
            Act.

    (d) [ ] Investment company registered under Section 8 of the Investment
            Company Act.

    (e) [X] An investment adviser in accordance with Rule
            13d-1(b)(1)(ii)(E);

    (f) [ ] An employee benefit plan or endowment fund in accordance with
            Rule 13d-1(b)(1)(ii)(F);

    (g) [ ] A parent holding company or control person in accordance with
            Rule 13d-1(b)(1)(ii)(G);

    (h) [ ] A savings association as defined in Section 3(b) of the Federal
            Deposit Insurance Act;

    (i) [ ] A church plan that is excluded from the definition of an
            investment company under Section 3(c)(14) of the Investment Company
            Act;

    (j) [ ] Group, in accordance with Rule 13d-1(b)(1)(ii)(J).

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CUSIP No. 902549807                 13G                        Page 4 of 5 Pages
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Item 4.         Ownership.

                The information in items 1 and 5 through 11 on the cover
                pages (p. 2) on Schedule 13G is hereby incorporated by
                reference.

Item 5.         Ownership of Five Percent or Less of a Class.

                If this statement is being filed to report the fact that as
                of the date hereof the reporting person has ceased to be the
                beneficial owner of more than five percent of the class of
                securities, check the following [ ].

Item 6.         Ownership of More than Five Percent on Behalf of Another Person.

                Not applicable.

Item 7.         Identification and Classification of the Subsidiary Which
                Acquired the Security Being Reported on by the Parent Holding
                Company or Control Person.

                Not applicable.

Item 8.         Identification and Classification of Members of the Group.

                Not applicable

Item 9.         Notice of Dissolution of Group.

                Not applicable.

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CUSIP No. 902549807                 13G                        Page 5 of 5 Pages
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Item 10.        Certification.

            By signing below the undersigned certifies that, to the best of its
knowledge and belief, the securities referred to above were not acquired and are
not held for the purpose of or with the effect of changing or influencing the
control of the issuer of the securities and were not acquired and are not held
in connection with or as a participant in any transaction having that purpose or
effect.


                                    SIGNATURE

            After reasonable inquiry and to the best of its knowledge and
belief, the undersigned certifies that the information set forth in this
statement is true, complete and correct.

Date: February 14, 2008

                                       Impala Asset Management LLC


                                       By:   /s/ Thomas Sullivan
                                          ------------------------------------
                                          Name:  Thomas Sullivan
                                          Title: Chief Financial Officer