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                                                                    Exhibit 10.6

                                                          Execution Copy

                    FIRST AMENDMENT TO SUPPLEMENTAL AGREEMENT

            THIS FIRST AMENDMENT TO SUPPLEMENTAL AGREEMENT (this "Amendment") is
made as of this 8th day of February, 2000 among Continental Airlines, Inc., a
Delaware corporation (the "Company"), Northwest Airlines Corporation, a Delaware
corporation formerly named Newbridge Parent Corporation (the "Stockholder"), and
Northwest Airlines Holdings Corporation, a Delaware corporation formerly named
Northwest Airlines Corporation ("Parent").

            WHEREAS, the Parent, the Stockholder and the Company have entered
into that certain Supplemental Agreement dated as of November 20, 1998 (the
"Supplemental Agreement").

            WHEREAS, the Company has entered into the First Amendment to Rights
Agreement, dated as of February 8, 2000, by and between the Company and Harris
Trust and Savings Bank (the "Rights Agreement Amendment").

            WHEREAS, the Parent, the Stockholder and the Company have entered
into that certain Amended and Restated Governance Agreement dated as of February
8, 2000 (the "Amended and Restated Governance Agreement").

            WHEREAS, the Parent, the Stockholder and the Company have determined
that it is desirable to amend the Supplemental Agreement to reflect therein the
amendments made in the Amended and Restated Governance Agreement and the Rights
Agreement Amendment.

            WHEREAS, this Amendment has been approved by a Majority Vote (as
defined in the Supplemental Agreement).

            NOW THEREFORE, the Parent, the Stockholder and the Company intending
to be legally bound, hereby agree as follows:
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            1. Capitalized terms not otherwise defined herein shall have their
respective meanings set forth in the Supplemental Agreement.

            2. The definition of "Eligible Rights Plan" in Section 28 of the
Supplemental Agreement shall be amended and restated in its entirety as follows:

            "Eligible Rights Plan" shall have the meaning set forth in Section
            7.01 (c) of the Governance Agreement.

            3. The definition of "Governance Agreement" in Section 28 of the
Supplemental Agreement shall be amended and restated in its entirety as follows:

            "Governance Agreement" shall mean the Amended and Restated
            Governance Agreement between the Company, the Parent and the
            Stockholder, dated as of February 8, 2000.

            4. The definition of "Rights Plan" in Section 28 of the Supplemental
Agreement shall be amended and restated in its entirety as follows:

            "Rights Plan" shall mean the Rights Agreement, dated as of November
            20, 1998, as amended by the First Amendment to Rights Agreement,
            dated as of February 8, 2000, between the Company and Harris Trust
            and Savings Bank.

            5. All references in the Supplemental Agreement to Newbridge Parent
Corporation, a Delaware corporation, are hereby modified to refer to Northwest
Airlines Corporation, a Delaware corporation.

            6. All references in the Supplemental Agreement to Northwest
Airlines Corporation, a Delaware corporation, are hereby modified to refer to
Northwest Airlines Holdings Corporation, a Delaware corporation.

            7. This Amendment may be signed in any number of counterparts, each
of which shall be an original, with the same effect as if the signatures thereto
and hereto were upon the same instrument.
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            8. Except as expressly modified by this Amendment, all of the terms,
conditions and provisions of the Supplemental Agreement shall remain unchanged
and in full force and effect.
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            IN WITNESS WHEREOF, the parties hereto have caused this First
Amendment to Supplemental Agreement to be executed as of the date first referred
to above.

                         NORTHWEST AIRLINES CORPORATION

                         By: /s/ Douglas M. Steenland
                            -------------------------
                            Douglas M. Steenland
                            Executive Vice President, General Counsel
                               and Secretary


                         NORTHWEST AIRLINES HOLDINGS CORPORATION

                         By: /s/ Douglas M. Steenland
                            -------------------------
                            Douglas M. Steenland
                            Executive Vice President, General
                               Counsel and Secretary


                         CONTINENTAL AIRLINES, INC.

                         By: /s/ Jeffery A. Smisek
                            ----------------------
                            Jeffery A. Smisek
                            Executive Vice President,
                               General Counsel and Secretary