<PAGE>   1



                                 EXHIBIT 10 (u)

<PAGE>   2

                                TERMINATION OF 
                         SUBSIDIARY GUARANTY AGREEMENT

         THIS TERMINATION OF SUBSIDIARY GUARANTY AGREEMENT (the "Termination
Agreement") is made and entered into as of this 11th day of September, 1996, by
and between ASA INVESTMENTS, INC., a Delaware corporation ("Guarantor") and
SUNTRUST BANK, ATLANTA, f/k/a Trust Company Bank (the "Bank").

             W   I   T   N   E   S   E   T   H        T   H   A   T

         WHEREAS, Guarantor has previously executed and delivered to the Bank
that certain Subsidiary Guaranty Agreement dated April 20, 1994 (the
"Guaranty") under which Guaranty the Guarantor has guaranteed certain
obligations owed by Atlantic Southeast Airlines, Inc. to the Bank as described
in the Guaranty (collectively the "Subject Obligations"); and


         WHEREAS, notwithstanding that the Subject Obligations shall remain in
existence, pursuant and in accordance with Item 9 of the Guaranty, the Bank and
the Guarantor desire to terminate the Guarantee so as to relieve the Guarantor
from all further responsibility and liability under the Guaranty.

         NOW THEREFORE, for and in consideration of the mutual promises
contained herein, Ten  ($10) Dollars in hand paid by Guarantor to the Bank, and
other  good and valuable consideration, the receipt, adequacy and sufficiency
of which is hereby acknowledged, the parties hereto do hereby agree as follows:

         1.      The parties hereby terminate the Guaranty and agree that the
Guaranty shall be of no further or continuing force or effect.  The Bank agrees
that the Guarantor is hereby relieved of all responsibilities, obligations, and
liabilities incurred under or in connection with the Guaranty and shall have no
responsibility whatsoever for all or any part of the Subject Obligations.  The
Bank does hereby for and on behalf of itself and its respective successors and
assigns, release, remise and forever discharge Guarantor and all of its
respective successors and assigns of and from any and all debts, claims, causes
of action, and other amounts arising under or in connection with the Guaranty
or the Subject Obligations.

         2.      This Termination Agreement shall be governed by the laws of
the State of Georgia.  This Termination Agreement may be executed in one or
more counterparts all of which together shall constitute one and the same
original.  This Termination Agreement shall be binding upon the parties hereto
and their respective heirs, successors, assigns, and legal representatives.


           (THE REMAINDER OF THIS PAGE IS INTENTIONALLY LEFT BLANK) 

<PAGE>   3

         IN WITNESS WHEREOF, the Guarantor and the Bank have each caused this
Termination Agreement to be executed by its duly authorized officers and its
seal to be affixed hereto as of the day and year first above written.


         SUNTRUST BANK, ATLANTA                 ASA INVESTMENTS, INC.
           f/k/a Trust Company Bank             
                                                
                                                
         By: /s/ R. Michael Dunlap              By: /s/ Ronald V. Sapp      
             ---------------------------            ----------------------
              Its: Vice President               Its: Treasurer
                                                
                                                
                                                
         By: /s/ Jenna M. Hale                  
             ---------------------------        
             Its: Banking Officer                  




                                      2