Exhibit 10(b)

                                 FIRST AMENDMENT
                                TO REVOLVING NOTE


         THIS FIRST AMENDMENT TO REVOLVING NOTE ("First Amendment"), made as of
March 31, 2000, by and between United Industrial Corporation, AAI Corporation,
AAI Engineering Support, Inc., AAI/ACL Technologies, Inc., AAI/ACL Technologies
Europe Limited, Detroit Stoker Company, Midwest Metallurgical Laboratory, Inc.,
UIC Products Co., Symtron Systems, Inc., and AAI MICROFLITE Simulation
International Corporation (collectively, the "Borrower"), and First Union
Commercial Corporation, a North Carolina Corporation (the "Lender").

                                    RECITALS

         A.       United Industrial Corporation and certain of its subsidiaries
                  entered into a Revolving Note, dated as of June 11, 1997, in
                  the maximum principal amount of Seventeen Million, Five
                  Hundred Thousand Dollars ($17,500,000.00) made payable to the
                  order of First Union Commercial Corporation (the "Revolving
                  Note").

         B.       The Revolving Note evidences Borrower's obligations to repay
                  advances of principal made by the Lender under a Revolving
                  Line of Credit Loan Agreement And Security Agreement, dated
                  June 11, 1997, as amended by First Amendment to Revolving Line
                  of Credit Loan Agreement and Security Agreement dated as of
                  October 1, 1998, by Second Amendment to Revolving Line of
                  Credit Loan Agreement and Security Agreement dated as of
                  December 31, 1998, and Third Amendment to Revolving Line of
                  Credit Loan Agreement and Security Agreement of even date
                  herewith (the "Loan Agreement"). The Revolving Note is
                  governed, in part, by certain provisions of the Loan
                  Agreement.

         C.       The Borrower and the Lender desire to amend the Revolving Note
                  for the purpose of extending the Maturity Date (as defined in
                  the Revolving Note) to January 11, 2001, for the purpose of
                  changing the definition of "Borrower" to the definition set
                  forth above and for certain other purposes hereinafter set
                  forth.

                                   AGREEMENTS

         NOW, THEREFORE, in consideration of the premises, the mutual agreements
herein contained, and other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the Borrower and the Lender hereby
agree as follows:

1.       Capitalized terms used in this First Amendment but not defined herein
         have the meanings ascribed to them in the Revolving Note. The term
         "Borrower" shall henceforth refer to the Persons encompassed by the
         term "Borrower" as defined above.


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2.       The Maturity Date is extended to and including January 11, 2001.

3.       Except as modified by this First Amendment, the Revolving Note remains
         in full force and effect and unmodified. Borrower warrants and
         represents that it has no offsets or defenses to its obligations under
         the Revolving Note, as modified by this First Amendment.

4.       In consideration of Lender's agreement to this First Amendment, the
         Borrower hereby releases and waives any and all claims of any kind that
         it may have against the Lender as of the date of this First Amendment
         arising out of or relating to the Loan Agreement or the Revolving Note,
         as amended by this First Amendment.

5.       ARBITRATION. UPON DEMAND OF ANY PARTY HERETO, WHETHER MADE BEFORE OR
         AFTER INSTITUTION OF ANY JUDICIAL PROCEEDING, ANY CONTROVERSY OR CLAIM
         ARISING OUT OF OR RELATING TO THE LOAN DOCUMENTS BETWEEN PARTIES HERETO
         (A "DISPUTE") SHALL BE RESOLVED BY BINDING ARBITRATION CONDUCTED UNDER
         AND GOVERNED BY THE COMMERCIAL FINANCIAL DISPUTES ARBITRATION RULES
         (THE "ARBITRATION RULES") OF THE AMERICAN ARBITRATION ASSOCIATION
         ("AAA") AND THE FEDERAL ARBITRATION ACT. DISPUTES MAY INCLUDE, WITHOUT
         LIMITATION, TORT CLAIMS, COUNTERCLAIMS, A DISPUTE AS TO WHETHER A
         MATTER IS SUBJECT TO ARBITRATION, CLAIMS BROUGHT AS CLASS ACTIONS, OR
         CLAIMS ARISING FROM DOCUMENTS EXECUTED IN THE FUTURE. A JUDGMENT UPON
         THE AWARD MAY BE ENTERED IN ANY COURT HAVING JURISDICTION.
         NOTWITHSTANDING THE FOREGOING, THIS ARBITRATION PROVISION DOES NOT
         APPLY TO DISPUTES UNDER OR RELATED TO SWAP AGREEMENTS. ALL ARBITRATION
         HEARINGS SHALL BE CONDUCTED IN THE CITY OR COUNTY WHERE THE LENDER'S
         OFFICE, AS FIRST STATED ABOVE, IS LOCATED, OR AT SUCH OTHER PLACE AS
         THE PARTIES MAY IN WRITING AGREE. A HEARING SHALL BEGIN WITHIN 90 DAYS
         OF DEMAND FOR ARBITRATION AND ALL HEARINGS SHALL CONCLUDE WITHIN 120
         DAYS OF DEMAND FOR ARBITRATION. THESE TIME LIMITS MAY NOT BE EXTENDED
         UNLESS A PARTY SHOWS CAUSE FOR EXTENSION AND THEN FOR NO MORE THAN A
         TOTAL OF 60 DAYS. THE EXPEDITED PROCEDURES SET FORTH IN RULE 51, ET
         SEQ., OF THE ARBITRATION RULES SHALL APPLY TO DISPUTES IN WHICH
         THE CLAIM IS LESS THAN $1,000,000.00. ARBITRATORS SHALL BE LICENSED
         ATTORNEYS SELECTED FROM THE COMMERCIAL FINANCIAL DISPUTE ARBITRATION
         PANEL OF THE AAA. THE PARTIES DO NOT WAIVE APPLICABLE FEDERAL OR STATE
         SUBSTANTIVE LAW EXCEPT AS PROVIDED HEREIN. NOTWITHSTANDING THE
         PRECEDING BINDING ARBITRATION PROVISIONS, THE PARTIES AGREE TO PRESERVE
         WITHOUT DIMINUTION, CERTAIN REMEDIES THAT ANY


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         PARTY MAY EXERCISE BEFORE OR AFTER AN ARBITRATION PROCEEDING IS
         BROUGHT. THE PARTIES SHALL HAVE THE RIGHT TO PROCEED IN ANY COURT OF
         PROPER JURISDICTION OR BY SELF HELP TO EXERCISE OR PROSECUTE THE
         FOLLOWING REMEDIES, AS APPLICABLE: (1) ALL RIGHTS TO FORECLOSE AGAINST
         ANY REAL OR PERSONAL PROPERTY OR OTHER SECURITY BY EXERCISING A POWER
         OF SALE OR UNDER APPLICABLE LAW BY JUDICIAL FORECLOSURE INCLUDING A
         PROCEEDING TO CONFIRM THE SALE; (2) ALL RIGHTS OF SELF HELP, INCLUDING
         WITHOUT LIMITATION, PEACEFUL OCCUPATION OF REAL PROPERTY AND COLLECTION
         OF RENTS, SETOFF, AND PEACEFUL POSSESSION OF PERSONAL PROPERTY; (3)
         OBTAINING PROVISIONAL OR ANCILLARY REMEDIES INCLUDING INJUNCTIVE
         RELIEF, SEQUESTRATION, GARNISHMENT, ATTACHMENT, APPOINTMENT OF RECEIVER
         AND FILING AN INVOLUNTARY BANKRUPTCY PROCEEDING; AND (4) WHEN
         APPLICABLE, A JUDGMENT BY CONFESSION OF JUDGMENT. ANY CLAIM OR
         CONTROVERSY WITH REGARD TO ANY PARTY'S ENTITLEMENT TO SUCH REMEDIES IS
         A DISPUTE. THE PARTIES AGREE THAT THEY SHALL NOT HAVE A REMEDY OF
         PUNITIVE OR EXEMPLARY DAMAGES AGAINST OTHER PARTIES IN ANY DISPUTE, AND
         THEY HEREBY WAIVE ANY RIGHT OR CLAIM TO PUNITIVE OR EXEMPLARY DAMAGES
         THEY MAY NOW HAVE OR WHICH MAY ARISE IN THE FUTURE IN CONNECTION WITH
         ANY DISPUTE WHETHER THE DISPUTE IS RESOLVED BY ARBITRATION OR
         JUDICIALLY.

6.       Lender has executed this First Amendment for the sole purpose of
         evidencing its consent hereto, and not for the purpose of becoming
         liable on the Revolving Note as a co-maker, endorser or guarantor.

7.       This Third Amendment may be signed in several counterparts which, when
         executed, shall constitute a single agreement. A counterpart containing
         a facsimile signature shall be effective to the same extent as if it
         were a counterpart containing an original signature, but shall be
         confirmed promptly with a counterpart containing an original signature.


BORROWER:                                 UNITED INDUSTRIAL CORPORATION

                                          By: /s/ Richard Erkeneff
                                              --------------------------------
                                              Richard Erkeneff, President



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                                       AAI CORPORATION

                                       By: /s/ Paul J. Michaud
                                           --------------------------------
                                           Paul J. Michaud, Vice President,
                                           Chief Financial Officer & Treasurer


                                       AAI ENGINEERING SUPPORT, INC.

                                       By: /s/ Paul J. Michaud
                                           --------------------------------
                                           Paul J. Michaud, Vice President,
                                           Chief Financial Officer & Treasurer


                                       AAI/ACL TECHNOLOGIES, INC.

                                       By: /s/ Paul J. Michaud
                                           --------------------------------
                                           Paul J. Michaud, Vice President &
                                           Chief Financial Officer


                                       AAI/ACL TECHNOLOGIES EUROPE LIMITED

                                       By: /s/ Paul J. Michaud
                                           --------------------------------
                                           Paul J. Michaud, Vice President &
                                           Chief Financial Officer


                                       DETROIT STOKER COMPANY

                                       By: /s/ James Perry
                                           --------------------------------
                                           James Perry
                                           Vice President



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<PAGE>
                                       MIDWEST METALLURGICAL LABORATORY, INC.

                                       By: /s/ James Perry
                                           --------------------------------
                                           James Perry
                                           Vice President


                                       UIC PRODUCTS CO.

                                       By: /s/ James Perry
                                           --------------------------------
                                           James Perry
                                           Vice President


                                       SYMTRON SYSTEMS, INC.

                                       By: /s/ Robert Worthing
                                           --------------------------------
                                           Robert Worthing, Vice President,
                                           General Counsel, and Assistant
                                           Secretary


                                       AAI MICROFLITE Simulation
                                       International Corporation

                                       By: /s/ Paul J. Michaud
                                           --------------------------------
                                           Paul J. Michaud
                                           President



CONSENTED TO:                    FIRST UNION COMMERCIAL CORPORATION

                                 By: /s/ Michael J. Landini
                                     --------------------------------------
                                     Michael J. Landini, Vice President


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STATE OF MARYLAND              )
                               ) To-wit:
COUNTY/CITY OF BALTIMORE       )


         I Darlene J. Koch, a Notary Public in and for the jurisdiction
aforesaid, do certify that James Perry, whose name is signed to the writing
above, bearing date as of April 3rd, 2000, has acknowledged the same before me
in my jurisdiction aforesaid.

         Given under my hand and seal this 3rd day of April, 2000.


                                                  /s/ Darlene J. Koch
                                                  -----------------------------
                                                  Notary Public

My Commission Expires:  Darlene J. Koch, Notary Public
                               Baltimore County
                              State of Maryland
                      My Commission Expires Dec. 1, 2001




STATE OF MARYLAND              )
                               ) To-wit:
COUNTY/CITY OF BALTIMORE       )


         I Darlene J. Koch, a Notary Public in and for the jurisdiction
aforesaid, do certify that Paul J. Michaud, whose name is signed to the writing
above, bearing date as of March 30, 2000, has acknowledged the same before me
in my jurisdiction aforesaid.

         Given under my hand and seal this 30th day of March, 2000.


                                                  /s/ Darlene J. Koch
                                                  -----------------------------
                                                  Notary Public

My Commission Expires:  Darlene J. Koch, Notary Public
                               Baltimore County
                              State of Maryland
                      My Commission Expires Dec. 1, 2001


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<PAGE>
STATE OF MARYLAND              )
                               ) To-wit:
COUNTY/CITY OF BALTIMORE       )


         I Darlene J. Koch, a Notary Public in and for the jurisdiction
aforesaid, do certify that Robert Worthing, whose name is signed to the writing
above, bearing date as of March 30th, 2000, has acknowledged the same before me
in my jurisdiction aforesaid.

         Given under my hand and seal this 30th day of March, 2000.


                                                  /s/ Darlene J. Koch
                                                  -----------------------------
                                                  Notary Public

My Commission Expires:  Darlene J. Koch, Notary Public
                               Baltimore County
                              State of Maryland
                      My Commission Expires Dec. 1, 2001




STATE OF MARYLAND              )
                               ) To-wit:
COUNTY/CITY OF BALTIMORE       )


         I Darlene J. Koch, a Notary Public in and for the jurisdiction
aforesaid, do certify that Richard Erkeneff, whose name is signed to the writing
above, bearing date as of March 30th, 2000, has acknowledged the same before me
in my jurisdiction aforesaid.

         Given under my hand and seal this 30th day of March, 2000.


                                                  /s/ Darlene J. Koch
                                                  -----------------------------
                                                  Notary Public

My Commission Expires:  Darlene J. Koch, Notary Public
                               Baltimore County
                              State of Maryland
                      My Commission Expires Dec. 1, 2001



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