Supplemental Agreement to Purchase Agreement No. 1670 - United Air Lines Inc. and The Boeing Co.


                  Supplemental Agreement No. 10
                               to
                   Purchase Agreement No. 1670
                             between
                       THE BOEING COMPANY
                               and
                     UNITED AIR LINES, INC.
            Relating to Boeing Model 747-422 Aircraft


          THIS SUPPLEMENTAL AGREEMENT, entered into as of the
11th day of April 1997, by and between THE BOEING COMPANY, a
Delaware corporation (hereinafter called Boeing), and UNITED AIR
LINES, INC., a Delaware corporation (hereinafter called Buyer);

                      W I T N E S S E T H:
                      -------------------          
                      
          WHEREAS, the parties entered into that certain Purchase
Agreement No. 1670, dated as of December 18, 1990, relating to
the purchase and sale of Boeing Model 747-422 aircraft
(hereinafter referred to as 'The Aircraft', or the 'Firm
Aircraft', [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY
WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST
FOR CONFIDENTIAL TREATMENT] or the 'Option Aircraft', as such
capitalized terms, and any other capitalized terms used herein,
unless otherwise specifically defined herein, are defined in the
'Purchase Agreement' (as such term is defined below)), which
agreement, as amended and supplemented, together with all
exhibits, specifications and letter agreements related or
attached thereto, is hereinafter called the 'Purchase Agreement'
and;

          WHEREAS, on July 12, 1996 Buyer and Boeing signed
Supplemental Agreement No. 9 to the Purchase Agreement; and

[*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR
CONFIDENTIAL TREATMENT]

          WHEREAS, Buyer and Boeing wish to make certain
additional amendments to the Purchase Agreement to reflect the
agreements set forth in Supplemental Agreement No. 9.

          NOW THEREFORE, in consideration of the mutual covenants
herein contained, the parties hereto agree to amend the Purchase
Agreement as follows:

1.       The Table of Contents is deleted in its entirety and
replaced with a new Table of Contents contained in Attachment 1
hereto.

P.A. No. 1670                  SA10-1

2.       Article 3, entitled Price of Aircraft is deleted in its
entirety and replaced with a new Article 3 contained in
Attachment 2 hereto.

3.       Delete the following 'Months to be Utilized in
Determining the Value of H & W' from the table on page 3 of
Exhibit D, entitled Price Adjustment due to Economic Fluctuations
- Airframe & Engine.

       Month of Scheduled
       Aircraft Delivery as Set            Months to be Utilized
       Forth in Article 2.1 of             Determining the Value
       the Agreement                       of H & W
       ------------------------            ---------------------

[*CONFIDENTIAL MATERIAL OMITTED            [*CONFIDENTIAL MATERIAL
AND FILED SEPARATELY WITH THE              OMITTED AND FILED SEPARATELY
SECURITIES AND EXCHANGE COMMISSION         WITH THE SECURITIES AND EX-
PURSUANT TO A REQUEST FOR CONFIDENTIAL     CHANGE COMMISSION PURSUANT
TREATMENT]                                 TO A REQUEST FOR CONFIDENTIAL
                                           TREATMENT]

4.       The Purchase Agreement is amended by adding Exhibit D-
1, entitled Price Adjustment due to Economic Fluctuations -
Airframe & Engine contained in Attachment 3 hereto.

[*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR
CONFIDENTIAL TREATMENT]

[*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR
CONFIDENTIAL TREATMENT]

6.       This Supplemental Agreement is subject to the
confidentiality provisions of Letter Agreement 6-1162-DLJ-886.

P.A. No. 1670                  SA10-2

7.       The Purchase Agreement shall be deemed amended to the
extent herein provided and as amended shall continue in full
force and effect.

EXECUTED IN DUPLICATE as of the day and year first above written.

THE BOEING COMPANY                     UNITED AIR LINES, INC.
                                       
By: /s/ M.D. Hurt                      By: /s/ Douglas A. Hacker
    -------------                          ---------------------

Its: Attorney In Fact                  Its: Senior Vice President and
     ----------------                       Chief Financial Officer
                                            -------------------------
P.A. No. 1670                  SA10-3

                        TABLE OF CONTENTS

                                                          Page
                                                          Number
                                                          ------

ARTICLE 1.     Subject Matter of Sale.......................1-1
ARTICLE 2.     Delivery of Aircraft; Title and Risk 
               of Loss......................................2-1
ARTICLE 3.     Price of Aircraft............................3-1
ARTICLE 4.     Taxes and Customs Duties.....................4-1
ARTICLE 5.     Payment......................................5-1
ARTICLE 6.     Excusable Delay..............................6-1
ARTICLE 7.     Changes to Detail Specification..............7-1
ARTICLE 8.     Federal Aviation Administration
               Requirements.................................8-1
ARTICLE 9.     Demonstration Flights and Test Data..........9-1
ARTICLE 10.    Assignment, Resale or Lease.................10-1
ARTICLE 11.    Termination for Certain Events..............11-1
ARTICLE 12.    Inspections; Plant Representatives..........12-1
ARTICLE 13.    Spare Parts and Certain Exhibit
               Documents...................................13-1
ARTICLE 14.    Notices and Requests........................14-1
ARTICLE 15.    Miscellaneous...............................15-1

EXHIBIT A      Aircraft Configuration.........................A

EXHIBIT B      Product Assurance Document.....................B

EXHIBIT C      Customer Support Document......................C

EXHIBIT D      Price Adjustment Due to Economic
               Fluctuations - Airframe and Engine.............D

EXHIBIT D-1    Price Adjustment Due to Economic
               Fluctuations - Airframe and Engine...........D-1

EXHIBIT E      Buyer Furnished Equipment Document.............E

EXHIBIT F      Acceptance Certificate.........................F

P.A. No 1670                      I

Attachment 2 to
Supplemental Agreement No. 10 to
Purchase Agreement No. 1670

ARTICLE 3.     Price of Aircraft.
               -----------------

       3.1     Basic Price.
               -----------

               3.1.1  Basic Price for Aircraft prior to
                      ---------------------------------
                      1997.

The basic price of each Aircraft scheduled for delivery prior to
January 1, 1997 shall be equal to the sum of [*CONFIDENTIAL
MATERIAL OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND
EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT] and (ii) such price adjustments applicable to such
Aircraft as may be made pursuant to the provisions of this
Agreement, including Article 7 (Changes to Detail Specification)
and Article 8 (FAA Requirements) or other written agreements
executed by Buyer and Boeing.

[*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR
CONFIDENTIAL TREATMENT]

       3.2       Purchase Price.  The purchase price of
each Aircraft shall be equal to the sum of the following items as
determined at the time of such Aircraft delivery: (i) the basic
price of such Aircraft, (ii) the Airframe and Engine Price
Adjustments to be determined pursuant to Exhibit D (Price
Adjustment Due to Economic Fluctuations - Airframe and Engine)
attached hereto [*CONFIDENTIAL MATERIAL OMITTED AND FILED
SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT
TO A REQUEST FOR CONFIDENTIAL TREATMENT] and the Airframe and
Engine Price Adjustments to be determined pursuant to Exhibit D-1
(Price Adjustment Due

P.A. No. 1670                    3-1

Attachment 2 to
Supplemental Agreement No. 10 to
Purchase Agreement No. 1670



to Economic Fluctuations -Airframe and Engine) attached hereto
[*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR
CONFIDENTIAL TREATMENT] and (iii) such price adjustments
applicable to such Aircraft as may be made pursuant to the
provisions of this Agreement, including Exhibit E (Buyer
Furnished Equipment Document) or other written agreements
executed by Boeing and Buyer (the 'Purchase Price').

P.A. No. 1670                    3-2

Attachment 3 to
Supplemental Agreement No. 10 to
Purchase Agreement No. 1670



              AIRFRAME AND ENGINE PRICE ADJUSTMENT

                             between

                       THE BOEING COMPANY

                               and

                     UNITED AIR LINES, INC.





          Exhibit D-1 to Purchase Agreement Number 1670

P.A. No. 1670

Attachment 3 to
Supplemental Agreement No. 10 to
Purchase Agreement No. 1670



                     PRICE ADJUSTMENT DUE TO
                     -----------------------
                      ECONOMIC FLUCTUATIONS
                      ---------------------
                    AIRFRAME PRICE ADJUSTMENT
                    -------------------------
                        (1995 Base Price)
                        -----------------

1.     Formula.
       -------

         For those Aircraft scheduled for delivery after
[*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR
CONFIDENTIAL TREATMENT] the Airframe Price Adjustment will be
determined at the time of Aircraft delivery in accordance with
the following formula:

         Pa = (P) (L + M - 1)

         Where:

         Pa = Airframe Price Adjustment.

         L = .65 x ECI
                   ---
                   130.1

         M = .35 x ICI
                   ---
                   123.6

         P = Aircraft Basic Price (as set forth in Article 3.1.3
             of this Agreement) less the base price of Engines (as
             defined in this Exhibit D-1) in the amount of
             [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH
             THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A
             REQUEST FOR CONFIDENTIAL TREATMENT]

       ECI = A value using the 'Employment Cost Index for workers
             in aerospace manufacturing' (aircraft manufacturing,
             standard industrial classification code 3721,
             compensation, base month and year June 1989 = 100), as
             released by the Bureau of Labor Statistics, U.S.
             Department of Labor on a quarterly basis for the months of
             March, June, September and December, calculated as
             follows:  A three-month arithmetic average value
             (expressed as a decimal and rounded to the nearest tenth)
             will be determined using the months set forth in the table
             below for the applicable Aircraft, with the released
             Employment Cost Index value described above for the month
             of March also being used for the months of January and
             February; the value for June

P.A. No. 1670                   D-1-1
PA/NEXD-1 

Attachment 3 to
Supplemental Agreement No. 10 to
Purchase Agreement No. 1670


             also used for April and May; the value for
             September also used for July and August; and the value for
             December also used for October and November.

       ICI = The three-month arithmetic average of the released
             monthly values for the Industrial Commodities Index as set
             forth in the 'Producer Prices and Price Index' (Base Year
             1982 = 100) as released by the Bureau of Labor Statistics,
             U.S. Department of Labor values (expressed as a decimal
             and rounded to the nearest tenth) for the months set forth
             in the table below for the applicable Aircraft.

          In determining the value of L, the ratio of ECI divided
by 130.1 will be expressed as a decimal rounded to the nearest
ten-thousandth and then multiplied by .65 with the resulting
value also expressed as a decimal and rounded to the nearest ten-
thousandth.

          In determining the value of M, the ratio of ICI divided
by 123.6 will be expressed as a decimal rounded to the nearest
ten-thousandth and then multiplied by .35 with the resulting
value also expressed as a decimal and rounded to the nearest ten-
thousandth.

Month of Scheduled
Aircraft Delivery as Set                   Months to be Utilized
Forth in Article 2.1 of                    in Determining the Value
the Agreement                              ECI and ICI
------------------------                   ------------------------


[*CONFIDENTIAL MATERIAL OMITTED            [*CONFIDENTIAL MATERIAL
AND FILED SEPARATELY WITH THE              OMITTED AND FILED SEPARATELY
SECURITIES AND EXCHANGE COMMISSION         WITH THE SECURITIES AND EX-
PURSUANT TO A REQUEST FOR CONFIDENTIAL     CHANGE COMMISSION PURSUANT
TREATMENT]                                 TO A REQUEST FOR CONFIDENTIAL
                                           TREATMENT]

2.     If at the time of delivery of an Aircraft Boeing is unable
to determine the Airframe Price Adjustment because the applicable
values to be used to determine the ECI and ICI have not been
released by the Bureau of Labor Statistics, then:

P.A. No. 1670                   D-1-2
PA/NEXD-1

Attachment 3 to
Supplemental Agreement No. 10 to
Purchase Agreement No. 1670


       2.1     The Airframe Price Adjustment, to be used at the
time of delivery of each of the Aircraft scheduled for delivery
after December 31, 1998, will be determined by utilizing the
escalation provisions set forth above.  The values released by
the Bureau of Labor Statistics and available to Boeing 30 days
prior to scheduled Aircraft delivery will be used to determine
the ECI and ICI values for the applicable months (including those
noted as preliminary by the Bureau of Labor Statistics) to
calculate the Airframe Price Adjustment.  If no values have been
released for an applicable month, the provisions set forth in
Paragraph 2.2 below will apply.  If prior to delivery of an
Aircraft the U.S. Department of Labor changes the base year for
determination of the ECI or ICI values as defined above, such
rebased values will be incorporated in the Airframe Price
Adjustment calculation.  The payment by Buyer to Boeing of the
amount of the Purchase Price for such Aircraft, as determined at
the time of Aircraft delivery, will be deemed to be the payment
for such Aircraft required at the delivery thereof.

       2.2     If prior to delivery of an Aircraft the U.S.
Department of Labor substantially revises the methodology used
for the determination of the values to be used to determine the
ECI and ICI values (in contrast to benchmark adjustments or other
corrections of previously released values), or for any reason has
not released values needed to determine the applicable Aircraft
Airframe Price Adjustment, the parties will, prior to delivery of
any such Aircraft, select a substitute for such values from data
published by the Bureau of Labor Statistics or other similar data
reported by non-governmental United States organizations, such
substitute to lead in application to the same adjustment result,
insofar as possible, as would have been achieved by continuing
the use of the original values as they may have fluctuated during
the applicable time period.  Appropriate revision of the formula
will be made as required to reflect any substitute values.
However, if within 24 months from delivery of the Aircraft the
Bureau of Labor Statistics should resume releasing values for the
months needed to determine the Airframe Price Adjustment, such
values will be used to determine any increase or decrease in the
Airframe Price Adjustment for the Aircraft from that determined
at the time of delivery of such Aircraft.

       2.3     In the event escalation provisions are made non-
enforceable or otherwise rendered null and void by any agency of
the United States Government, the parties agree,

P.A. No. 1670                   D-1-3
PA/NEXD-1

Attachment 3 to
Supplemental Agreement No. 10 to
Purchase Agreement No. 1670


to the extent they may lawfully do so, to equitably adjust the
Purchase Price of any affected Aircraft to reflect an allowance
for increases or decreases in labor compensation and material
costs occurring since February, 1995, which is consistent with
the applicable provisions of paragraph 1 of this Exhibit D.

3.     For the calculations herein, the values released by the
Bureau of Labor Statistics and available to Boeing 30 days prior
to scheduled Aircraft delivery will be used to determine the ECI
and ICI values for the applicable months (including those noted
as preliminary by the Bureau of Labor Statistics) to calculate
the Airframe Price Adjustment.

Note:  Any rounding of a number, as required under this
       Exhibit D-1 with respect to escalation of the airframe
       price, will be accomplished as follows: if the first digit
       of the portion to be dropped from the number to be rounded
       is five or greater, the preceding digit will be raised to
       the next higher number.

P.A. No. 1670                   D-1-4
PA/NEXD-1

Attachment 3 to
Supplemental Agreement No. 10 to
Purchase Agreement No. 1670



            ENGINE PRICE ADJUSTMENT - PRATT & WHITNEY
            -----------------------------------------
                        (1995 BASE PRICE)
                        -----------------

(a)     The Aircraft Basic Price of each Aircraft scheduled for
delivery [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY
WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST
FOR CONFIDENTIAL TREATMENT] as set forth in Article 3.1.3 of this
Agreement, includes an aggregate price for PW4056 engines and all
accessories, equipment and parts therefor provided by the engine
manufacturer (collectively in this Exhibit D-1 called 'Engines')
of [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR
CONFIDENTIAL TREATMENT].  The adjustment in Engine price
applicable to each such Aircraft ('Engine Price Adjustment'
herein) will be determined at the time of Aircraft delivery in
accordance with the following formula:

       Pa  =  (P)  (AA  +  BB  +  CC)  -  P

(b)    The following definitions will apply herein:

       Pa  =  Engine Price Adjustment


       P   =  Aggregate Engine Base Price as set forth in
              paragraph (a) above.

       AA  = .60  x  L
                    ---         
                    $17.80

       BB  = .30  x  M
                    ---
                    130.6

       CC  = .10  x  E
                    ---         
                    76.6

In determining the value of AA, BB and CC, the ratio of L divided
by  $17.80,  M  divided by 130.6 and E divided by  76.6  will  be
expressed  as a decimal and rounded to the nearest ten-thousandth
but  the decimal value resulting from multiplying such ratios  by
the  respective constants (.60, .30 and .10) will not be rounded.
The  value of the sum of AA + BB + CC will also be rounded to the
nearest ten-thousandth.

       L   =  Labor  Index, which is the 'Hourly Earnings  of
              Aircraft  Engines and Engine Parts Production Workers, SIC
              3724'  published  by the Bureau of Labor  Statistics,  U.S.
              Department of Labor,

P.A. No. 1670                   D-1-5
PA/NEXD-1

Attachment 3 to
Supplemental Agreement No. 10 to
Purchase Agreement No. 1670


              for the seventh month preceding the month of
              scheduled Aircraft delivery.

   $17.80  =  Published Labor Index (SIC 3724) for December, 1994.

        M  =  Material Index, which is the 'Producer Price Index
              - Code 10, Metals and Metal Products,' (Base Year 1982 =
              100) published by the Bureau of Labor Statistics, U.S.
              Department of Labor, for the seventh month preceding the
              month of scheduled Aircraft delivery.

    130.6  =  Published Material Index (Code 10) for December, 1994.

        E  =  Fuel Index, which is the 'Producer Price Index -
              Code 5, Fuels and Related Products and Power' (Base Year
              1982 = 100) published for the Bureau of Labor Statistics,
              U.S. Department of Labor, for the seventh month preceding
              the month of scheduled Aircraft delivery.

     76.6  =  Published Fuel Index (Code 5) for December, 1994.

The Engine Price Adjustment will not be made if it would result
in a decrease in the aggregate Engine base price.

(c)     The value of the Labor, Material and Fuel Index used in
determining the Engine Price Adjustment will be those published
by the Bureau of Labor Statistics, U.S. Department of Labor as of
a date 30 days prior to the scheduled Aircraft delivery to Buyer.
Such Index values will be considered final and no revision to the
Engine Price Adjustment will be made after Aircraft delivery for
any subsequent changes in published Index values.

(d)     If the Bureau of Labor Statistics, U. S. Department of
Labor, (i) substantially revises the methodology (in contrast to
benchmark adjustments or other corrections of previously
published data), or (ii) discontinues publication of any of the
data referred to above or (iii) temporarily discontinues
publication of any of the data referred to above, Pratt & Whitney
Aircraft (P&WA) agrees to meet jointly with Boeing and Buyer and
jointly select a substitute for the revised or discontinued data, such

P.A. No. 1670                   D-1-6
PA/NEXD-1

Attachment 3 to
Supplemental Agreement No. 10 to
Purchase Agreement No. 1670


substitute data to lead in application to the same adjustment
result, insofar as possible, as would have been achieved by
continuing the use of the original data as it may have fluctuated
had it not been revised or discontinued.  Appropriate revision of
the Engine Price Adjustment provisions set forth above will be
made to accomplish this result for affected Engines.

In the event the Engine Price Adjustment escalation provisions of
this Agreement are made non-enforceable or otherwise rendered
null and void by any agency of the United States Government, P&WA
agrees to meet jointly with Boeing and Buyer and jointly agree,
to the extent that they may lawfully do so, to adjust equitably
the purchase price of the Engine(s) to reflect an allowance for
increases in labor, material and fuel costs that occurred from
December, 1994 to the seventh month preceding the month of
scheduled delivery of the applicable Aircraft.

NOTES:  Any rounding of a number, as required under this
        Exhibit D-1 with respect to escalation of the Engine
        price, will be accomplished as follows: if the first
        digit of the portion to be dropped from the number to be
        rounded is five or greater, the preceding digit will be
        raised to the next higher number.