Supplemental Agreement to Purchase Agreement No. 1663 - United Air Lines Inc. and The Boeing Co.


                    Supplemental Agreement No. 4  

                               to
                                
                   Purchase Agreement No. 1663

                             between

                       The Boeing Company

                               and

                      UNITED AIR LINES, INC.

            Relating to Boeing Model 777-222 Aircraft


   THIS SUPPLEMENTAL AGREEMENT, entered into as of the 30th day
of May, 1996, 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 hereto entered into an agreement
dated as of December 18, 1990, relating to Boeing Model 777-222
aircraft (hereinafter referred to as the 'Aircraft'), which
agreement, as amended, together with all exhibits and
specifications attached thereto and made a part thereof which is
hereinafter called the 'Purchase Agreement' and;

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

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

1.  Article 1, 'Subject Matter of Sale', is hereby deleted in
its entirety and replaced with a new Article 1, which is
Attachment No. 1 hereto.

2.  Article 2, 'Delivery of Aircraft; Title and Risk of Loss',
is hereby deleted in its entirety and replaced with a new Article
2 which is Attachment No. 2 hereto.

3.  Article 5, 'Payment', is hereby deleted in its entirety and
replaced with a new Article 5 which is Attachment No. 4 hereto.

4.  The two 'B' Market Aircraft, which are the subject of this
Supplemental Agreement, are [*CONFIDENTIAL MATERIAL OMITTED AND
FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION
PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT] as such term is
defined in Letter Agreement No. 6-1162-TML-1205 to nine (9) 737
Aircraft in Purchase Agreement No. 1595, [*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] will be applied to the advance payments
owed Boeing for the two 'B' Market Aircraft which are the subject
of this Supplemental Agreement.  An adjustment for the amount
owed by Buyer [*CONFIDENTIAL MATERIAL OMITTED AND FILED
SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT
TO A REQUEST FOR CONFIDENTIAL TREATMENT] for each of
[*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR
CONFIDENTIAL TREATMENT] 777 aircraft, is reflected in paragraph
6 below.

6.  Paragraph 6 of Letter Agreement No. 6-1162-RCN-859 provides that
the advance payments paid by Buyer will be based on the
[*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE
SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR
CONFIDENTIAL TREATMENT] The calculations are based on a June 3,
1996 settlement date.

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

*See Paragraph no. 5

The difference will be refunded to Buyer in accordance with paragraph 6.D.
of Letter Agreement No. 6-1162-TML-1205.

    
P.A. No. 1663                S4-2


7.  In consideration of Buyer's purchase of the 777 Aircraft,
which are the subject of this Supplemental Agreement, Boeing
agrees to [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY
WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST
FOR CONFIDENTIAL TREATMENT]  pursuant to paragraph 7 of Letter
Agreement No. 6-1162-TML-1205  [*CONFIDENTIAL MATERIAL OMITTED
AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION
PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT]


8.  Buyer agrees that the invoice for each of the two (2) 'B'
Market Aircraft, which are the subject of this Supplemental
Agreement, will contain a [*CONFIDENTIAL MATERIAL OMITTED AND
FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION
PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT]  pursuant to
paragraph 13 of Letter Agreement No. 6-1162-TML-1205.

9.  Buyer agrees that the credit memorandum applicable to the
two (2) 'B' Market Aircraft, which are the subject of this
Supplemental Agreement, and discussed in Letter Agreement 6-1162-
RCN-859 will include:

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

10.  This Supplemental Agreement, including all of the
Attachments, will be treated as privileged and confidential
information pursuant to the terms of Letter Agreement No. 6-1162-
DLJ-832.

The Purchase Agreement shall be deemed to be supplemented to the
extent herein provided and as so supplemented 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.O. Hurt             By: /s/ Douglas A. Hacker
    -------------                 ---------------------
                                  Douglas A. Hacker
Its:  Attorney-In-Fact        Its: Senior Vice President and
                                   Chief Financial Officer


P.A. No. 1663                S4-3


Attachment No. 1
Supplemental Agreement No. 4
Purchase Agreement No. 1663
United Air Lines, Inc.
Page 1

ARTICLE 1.    Subject Matter of Sale.
              ----------------------

              1.1.1 'A' Market Aircraft Description'.
Boeing shall sell and deliver to Buyer, and Buyer shall purchase
from Boeing, sixteen (16) Boeing Model 777-222 'A' Market
Aircraft.  Such aircraft are referred to individually and
collectively as the 'Aircraft' or 'AIRCRAFT' or 'the 'A' Market
Aircraft'.  The Aircraft will be manufactured by Boeing in
accordance with Boeing Detail Specification [*CONFIDENTIAL
MATERIAL OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND
EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL
TREATMENT]  (as modified and described in Exhibit A-1 attached
hereto) as it may be modified from time to time in accordance
with the terms and conditions of Article 7 herein.  Such Detail
Specification as so modified is by this reference incorporated in
this Agreement and is hereinafter referred to as the 'Detail
Specification' or 'the 'A' Market Detail Specification.' In
connection with the sale and purchase of the Aircraft, Boeing
shall also deliver to Buyer other things under this Agreement
including data, documents, training and services.

              1.1.2 'B' Market Aircraft Description'.  Boeing
shall sell and deliver to Buyer, and Buyer shall purchase from
Boeing, twenty (20) Boeing Model 777-222 'B' Market Aircraft.
Such aircraft are referred to individually and collectively as
the 'Block A 'B' Market Aircraft', 'Block B 'B' Market Aircraft',
'Aircraft' or 'AIRCRAFT' or 'the 'B' Market Aircraft'.  The
Aircraft will be manufactured by Boeing in accordance with Boeing
Detail Specification [*CONFIDENTIAL MATERIAL OMITTED AND FILED
SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT
TO A REQUEST FOR CONFIDENTIAL TREATMENT]  (as modified and
described in Exhibit A-2 attached hereto) as it may be modified
from time to time in accordance with the terms and conditions of
Article 7 herein.  Such Detail Specification as so modified is by
this reference incorporated in this Agreement and is hereinafter
referred to as the 'Detail Specification' or 'the 'B' Market
Detail Specification.' In connection with the sale and purchase
of the Aircraft, Boeing shall also deliver to Buyer other things
under this Agreement including data, documents, training and
services.

              1.2   Performance Guarantees.  Any performance
guarantees applicable to the Aircraft shall be expressly included
in this Agreement.


                             
P.A. No. 1663                S4-1

Attachment No. 2
Supplemental Agreement No. 4
Purchase Agreement No. 1663
United Air Lines, Inc.
Page 2

ARTICLE 2.    Delivery of Aircraft: Title and Risk of Loss.
              --------------------------------------------

2.1 Time of Delivery.  Each Aircraft shall be delivered to Buyer
assembled and ready for flight, and Buyer shall accept delivery
of such Aircraft during or, if mutually agreed, before the months
set forth in the following schedule:

              'Month and Year
                of Delivery          Quantity of Aircraft
                -----------          --------------------

                         'A' Market Aircraft
                          ------------------
                 May 1995                 Three (3)
                 June 1995                Two   (2)
                 July 1995                One   (1)
                 September 1995           One   (1)
                 October 1995             One   (1)
                 November 1995            One   (1)
                 December 1995            Two   (2)
                 February  1996           One   (1)
                 April 1996               One   (1)
                 May 1996                 One   (1)
                 June 1996                One   (1)
                 July 1996                One   (1)

                         'B' Market Aircraft
                          ------------------

                     Block A 'B' Market Aircraft
                     ---------------------------

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

                     

P.A. No. 1663                S4-1

Attachment No. 2
Supplemental Agreement No. 4
Purchase Agreement No. 1663
United Air Lines, Inc.
Page 2

                   Block B 'B' Market Aircraft
                   ---------------------------

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

If Boeing gives Buyer at least ten (10) days' advance notice of
the delivery date for an Aircraft, and delivery is delayed beyond
such date due to Buyer's fault or responsibility, Buyer shall
promptly reimburse Boeing for all costs and expenses incurred by
Boeing as a result of such delay, including but not limited to
reasonable amounts for storage, insurance, taxes, preservation or
protection of the Aircraft, and interest on payments due.

              2.2   Place of Delivery.  Each Aircraft shall be
delivered at an airport in the State of Washington selected by
Boeing or at such alternate site as may be mutually agreed upon
in writing.  If delivery is made at an alternate site at Buyer's
request, Buyer shall promptly reimburse Boeing for any increased
costs incurred by Boeing as a result thereof.

              2.3   Title and Risk of Loss.  Title to and risk of
loss of each Aircraft shall pass from Boeing to Buyer upon
delivery of such Aircraft but not prior to thereto.

              2.4   Documents of Title.  Upon delivery of and
payment for each Aircraft, Boeing shall deliver to Buyer a bill
of sale duly conveying to Buyer good title to such Aircraft free
and clear of all liens, claims, charges and encumbrances of every
kind whatsoever, and such other appropriate documents of title as
Buyer may reasonably request.


              
P.A. No. 1663                S4-2

Attachment No. 3 to
Supplemental Agreement No. 4
Purchase Agreement No. 1663
1663-5 Page 4

ARTICLE 5.    Payment.
              -------

5.1  Advance Payment Base Price.  The advance payment base price
of each Aircraft, depending on the month and year of scheduled
delivery, is indicated below:

     Month and Year of                   Advance Payment Base
     Scheduled Delivery                   Price per Aircraft
     ------------------                   ------------------

     'A' Market Aircraft
     -------------------

     May 1995
     June 1995
     July 1995
     September 1995
     October 1995                          [*CONFIDENTIAL MATERIAL
     November 1995                         OMITTED AND FILED
     December 1995                         SEPARATELY WITH THE
     February  1996                        SECURITIES AND EXCHANGE
     April 1996                            COMMISSION PURSUANT TO A
     May 1996                              REQUEST FOR CONFIDENTIAL
     June 1996                             TREATMENT]
     July 1996


     'B' Market Aircraft
     -------------------

     Block A 'B' Market Aircraft
     ---------------------------

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

     Block B 'B' Market Aircraft
     ---------------------------

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


Attachment No. 3 to
Supplemental Agreement No. 4
Purchase Agreement No. 1663
1663-5 Page 4

Such advance payment base prices will be used to determine the
amount of the first advance payment to be made by Buyer on each
Aircraft pursuant to the provisions of Article 5.2. The advance
payment base price of each Aircraft has been established using
currently available forecast of the escalation factors used by
Boeing and applicable to the scheduled month and year of Aircraft
delivery.  The advance payment base prices will be further
increased or decreased by Boeing not later than twenty-five (25)
months prior to the scheduled month of delivery, as required to
reflect the effects of the then-current forecasted escalation
factors used by Boeing in accordance with Exhibit D. The advance
payment base price of each Aircraft, including any adjustments
made thereto, as contemplated herein, is referred to as the
'Advance Payment Base Price.'

              5.2   Advance Payments.  Buyer shall pay to Boeing
advance payments for each Aircraft on the dates indicated in the
schedule below.  The advance payment amount for an Aircraft due
on a payment date shall be equal to (i) the sum of the advance
payment percentages given in such schedule through the payment
date multiplied by the Advance Payment Base Price for the
Aircraft provided to Buyer pursuant to Article 5.1 for such
payment date, less (ii) the sum of the advance payment amounts
paid by Buyer to Boeing on such Aircraft up to such payment date.


Attachment No. 3 to
Supplemental Agreement No. 4
Purchase Agreement No. 1663
1663-5 Page 4

     Due Date of Payment                Amount Due per Aircraft
     -------------------                -----------------------

     Upon execution of a definitive
     purchase agreement

     24 months prior to the first
     day of the scheduled delivery
     month of the Aircraft

     21 months prior to the first
     day of the scheduled delivery
     month of the Aircraft
                                        [*CONFIDENTIAL MATERIAL
     18 months prior to the first       OMITTED AND FILED
     day of the scheduled delivery      SEPARATELY WITH
     month of the Aircraft              THE SECURITIES AND
                                        EXCHANGE COMMISSION
     15 months prior to the first       PURSUANT TO A REQUEST
     day of the scheduled delivery      FOR CONFIDENTIAL
     month of the Aircraft              TREATMENT]

     12 months prior to the first
     day of the scheduled delivery
     month of the Aircraft

     9 months prior to the first
     day of the scheduled delivery
     month of the Aircraft

     6 months prior to the first
     day of the scheduled delivery
     month of the Aircraft


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

              5.3   Payment for Aircraft.  Concurrently with delivery
of each Aircraft, Buyer shall pay to Boeing the Purchase Price
thereof, less the total amount of advance payments theretofore
received by Boeing for such Aircraft under Article 5.2.

              5.4   Repayment of Advance Payments.  If this Agreement
is terminated with respect to any Aircraft (i) by Buyer under
Article 6.2, (ii) by Buyer under Article 11, or (iii) by failure
of Buyer to provide Boeing with written notice pursuant to
Article 6.4, then Boeing shall promptly repay to Buyer, without
interest, any advance payments received by Boeing from Buyer here
under with respect to any Aircraft so terminated.  If this
Agreement is terminated by Boeing under Article 6.2, then Boeing
shall promptly repay


Attachment No. 3 to
Supplemental Agreement No. 4
Purchase Agreement No. 1663
1663-5 Page 4

to Buyer with interest any advance payments received by Boeing
from Buyer hereunder with respect to any Aircraft so terminated.


              5.5   Payment in United States Funds.  All prices
and payments set forth in this Agreement are in United States
Dollars.  All payments required under this Agreement shall be
made in United States Dollars and in immediately available funds
by (i) transfer to the party to receive payment of a cashier's
check drawn on a member bank, located at Seattle, Washington, of
the United States Federal Reserve System mutually acceptable to
the parties, or (ii) unconditional deposit to the account of the
party to receive payment in a bank in the United States mutually
acceptable to the parties.  Buyer shall comply with all
applicable monetary and exchange control regulations, and shall
obtain any necessary authority from the governmental agency
administering such regulations in order to enable Buyer to make
payments at the time and place and in the manner and medium
specified herein.



Supplemental Agreement No. 4
Purchase Agreement No. 1663

                    

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