<PAGE>
                                                                    Exhibit 4.20


           FOURTH AMENDMENT TO LOAN AND SECURITY AGREEMENT AND WAIVER


     THIS FOURTH AMENDMENT TO LOAN AND SECURITY AGREEMENT AND WAIVER (this
"Amendment"), dated as of August 1,2003, is entered into by and among WELLS
FARGO FOOTHILL, INC., a California corporation, as agent (in such capacity,
"Agent") for the Lenders (defined below), the Lenders signatory hereto, MERCURY
AIR GROUP, INC. ("Parent") and Parent's Subsidiaries signatory hereto (together
with Parent, "Borrowers" and each sometimes referred to as a "Borrower").

                                    RECITALS

     A. Borrowers, Agent and the financial institutions from time to time party
thereto (the "Lenders") have previously entered into that certain Loan and
Security Agreement, dated as of December 30,2002, as amended by that certain
First Amendment to Loan and Security Agreement, dated as of March 12,2003, that
certain Second Amendment to Loan and Security Agreement, dated as of March 31,
2003 and that certain Third Amendment to Loan and Security Agreement, dated as
of July 16,2003 (as amended, the "Loan Agreement"), pursuant to which the
Lenders have made certain loans and financial accommodations available to the
Borrowers. Capitalized terms used herein without definition shall have the
meanings ascribed thereto in the Loan Agreement as amended hereby.

     B. Borrowers have not provided to Lender the Notices of Assignments of
Claims required to be delivered pursuant to Section 3.2(1) of the Loan Agreement
on or before June 30, 2003, and therefore an Event of Default has occurred (the
"Known Existing Default").

     C. Borrowers have requested that Agent and the Lenders waive the Known
Existing Default and amend the Loan Agreement as provided herein.

     D. Agent and the Lenders are willing to waive the Known Existing Default
and, along with the Borrowers, amend the Loan Agreement under the terms and
conditions set forth in this Amendment. Borrowers are entering into this
Amendment with the understanding and agreement that, except as specifically
provided herein, none of Agent's or any Lender's rights or remedies as set forth
in the Loan Agreement is being waived or modified by the terms of this
Amendment.

                                   AGREEMENT

     NOW, THEREFORE, in consideration of the foregoing and the mutual covenants
herein contained, and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereby agree as
follows (initially capitalized terms used herein without definition shall have
the meanings given in the Loan Agreement):

     1. Amendments to Loan Agreement.

         (a) The definition of "Assignment of Claims" is hereby amended to read
as follows:




<PAGE>


                  ""Assignment of Claims" means an Assignment of Claims Under
         Government Contract, in form and substance acceptable to Agent, with
         respect to a contract under which a Government Account may be created
         or otherwise arise."

         (b) Clause (g) of the definition of "Eligible Accounts" set forth in
Section 1.1 of the Loan Agreement is hereby amended to read as follows:

                  "(g) Government Accounts with respect to which Agent has not
         received both an Assignment of Claims and a Notice of Assignment of
         Claims unless such Account is owed by a state that does not have a
         statutory counterpart to the Assignment of Claims Act,"

         (c) The definition of "Notice of Assignment of Claims" set forth in
Section 1.1 of the Loan Agreement is hereby amended to read as follows:

                  ""Notice of Assignment of Claims" means a Notice of Assignment
         of Claims, in form and substance acceptable to Agent, pursuant to
         which, among other things, a copy of an Assignment of Claims is
         delivered to the contracting and disbursing officer for the contract
         referenced in such Assignment of Claims, and which has been
         counter-executed or otherwise acknowledged in a manner satisfactory to
         Agent, by such contracting officer and disbursing officer."

         (d) The following definitions are hereby added, in alphabetical order,
to Section 1.1 of the Loan Agreement:

                  "Existing Government Accounts" means Government Accounts (a)
         arising under any contract listed on Schedule E-1 attached hereto, (b)
         which substantially reflect the Government Accounts which were reported
         to Agent in a borrowing base on July 7,2003, (c) which, except for the
         fact that Agent has not received an Assignment of Claims and a Notice
         of Assignment of Claims with respect to each contract giving rise to
         such Government Accounts, constitute Eligible Accounts, and (d) with
         respect to which the applicable Borrower has instructed the account
         debtor therefor to remit all payments thereon to a Cash Management
         Account.

                  "Government Accounts" mean Accounts with respect to which the
         Account Debtor is any of the United States, any department, agency, or
         instrumentality of the United States or any state of the United States.

                  "Government Contract Certification" means a certificate
         substantially in the form of Exhibit C-2 hereto and otherwise in form
         and substance satisfactory to Agent.

                  "New Government Accounts" means Government Accounts (a)
         arising under contracts entered into and reported to Agent after July
         10, 2003, (b) with respect to which Borrowers have delivered to Agent
         an Assignment of Claims, a Notice of Assignment of Claims (executed by
         the applicable Borrower but not by



                                       2
<PAGE>


         the contracting officer or disbursing officer with respect thereto) and
         a Government Contract Certification, (c) which, except for the fact
         that Agent has not received an Assignment of Claims and a Notice of
         Assignment of Claims with respect to each contract giving rise to such
         Government Accounts, constitute Eligible Accounts, (d) with respect to
         which 45 days have not elapsed since the delivery to Agent of the
         Government Contract Certification therefor, and (e)with respect to
         which the applicable Borrower has instructed the account debtor
         therefor to remit all payments thereon to a Cash Management Account.

         (e) The second sentence of Section 2.l(a) of the Loan Agreement is
hereby amended to read as follows:

         "For purposes of this Agreement, "Borrowing Base," as of any date of
         determination, shall mean the result of:

                  (x) the lesser of

                           (i) the sum of

                                    (A) 85% of the amount of Eligible Accounts
                           plus

                                    (B) the lesser of (1) 85% of Eligible
                           Foreign Accounts or (2) $2,000,000 plus

                                    (C) 85% of the amount, if any, of Existing
                           Government Accounts; provided, however, if (1) on
                           September 1, 2003, Agent has not received Notices of
                           Assignment of Claims with respect to any government
                           contract giving rise to Existing Government Accounts,
                           such advance rate shall be reduced on September 15,
                           2003 to 42.5% and (2) on September 30, 2003, Agent
                           has not received Notices of Assignment of Claims with
                           respect to any government contract giving rise to
                           Existing Government Accounts, such advance rate shall
                           be reduced to 0% on such date, plus

                                    (D) 40% of the amount, if any, of New
                           Government Accounts; less

                                    (E) the amount, if any, of the Dilution
                           Reserve, and

                           (ii) an amount equal to Borrowers' Collections with
                  respect to Accounts for the immediately preceding 45 day
                  period, minus

                  (y) the sum of the Bank Product Reserve, the Availability
         Block, the Asset Sale Reserve and the aggregate amount of all other
         reserves, if any,



                                       3
<PAGE>


         established by Agent under Section 2.1(b)."

         (f) That portion of the table set forth in Section 6.2 of the Loan
Agreement categorized as "Quarterly" and "Upon request by Agent" are hereby
amended to read as follows:

"Quarterly"                (p) a detailed list of each Borrower's customers,

                           (q) a report regarding each Borrower's accrued, but
                           unpaid, ad valorem taxes,

                           (r) on the last day of each calendar quarter,
                           commencing with the quarter ending September 30,
                           2003, a schedule of all contracts under which any
                           Borrower is engaged in supplying any goods or
                           services to the United States, any department,
                           agency, or instrumentality of the United States or
                           any State of the United States, indicating, with
                           respect to cash such contract, whether Accounts
                           arising from such contract have been included in any
                           Borrowing Base report submitted to Lender and the
                           date of such report, the contracting parties, the
                           contract number, the name and address of the
                           contracting officer, if applicable, the name and
                           address of the disbursing officer, if applicable, the
                           effective dates of such contract, and whether such
                           contract is new or an extension or renewal of an
                           existing contract, and

                           (s) on the last day of each calendar quarter,
                           commencing with the quarter ending September 30,
                           2003, a schedule of all motor vehicles owned by any
                           Borrower.

Upon occurrence            (t) within 3 business days after any Borrower enters
                           into a contract which gives rise to Government
                           Accounts, a Government Contract Certification with
                           respect to such contract.

Upon request by Agent      (u) copies of invoices in connection with the
                           Accounts, credit memos, remittance advices, deposit
                           slips, shipping and delivery documents in connection
                           with the Accounts and, for Inventory and Equipment
                           acquired by Borrowers, purchase orders and invoices,
                           and

                           (v) such other reports as to the Collateral, or the
                           financial condition of Borrowers as Agent may
                           request."



All existing references to Section 6.2(r) of the Loan Agreement shall hereafter
mean and be a reference to Section 6.2(u). All existing references to Section
6.2(s) of the Loan Agreement shall



                                       4
<PAGE>


hereafter mean and be a reference to Section 6.2(v).

         (g) Exhibit C-2 to this Amendment is hereby added to the Loan Agreement
as Exhibit C-2 thereto.

         (h) Schedule E-1 to this Amendment is hereby added to the Loan
Agreement as Schedule E-1 thereto.

     2. Waiver of Known Existing Default. Agent and each Lender hereby waives
enforcement of its rights against Borrowers arising from the Known Existing
Default; provided, however, nothing herein shall be deemed a waiver with respect
to any failure of Borrowers to comply fully with any Section of the Loan
Agreement referenced herein (as amended by this Amendment). This waiver shall be
effective only for the specific default comprising the Known Existing Default,
and in no event shall this waiver be deemed to be a waiver of enforcement of
Agent's or any Lender's rights with respect to any other Default or Event of
Default now existing or hereafter arising. Nothing contained in this Amendment
nor any communications between any Borrower and either Agent or any Lender shall
be a waiver of any rights or remedies Agent or any Lender has or may have
against any Borrower, except as specifically provided herein. Except as
specifically provided herein, Agent and each Lender hereby reserve and preserve
all of their respective rights and remedies against Borrowers under the Loan
Agreement and the other Loan Documents.

     3. Release; Covenant Not to Sue.

         (a) Each Borrower hereby absolutely and unconditionally releases and
forever discharges Agent and each Lender, and any and all participants, parent
corporations, subsidiary corporations, affiliated corporations, insurers,
indemnitors, successors and assigns thereof, together with all of the present
and former directors, officers, agents and employees of any of the foregoing
(each a "Released Party"), from any and all claims, demands or causes of action
of any kind, nature or description, whether arising in law or equity or upon
contract or tort or under any state or federal law or otherwise, which such
Borrower has had, now has or has made claim to have against any such person for
or by reason of any act, omission, matter, cause or thing whatsoever arising
from the beginning of time to and including the date of this Amendment, whether
such claims, demands and causes of action are matured or unmatured or known or
unknown. It is the intention of each Borrower in providing this release that the
same shall be effective as a bar to each and every claim, demand and cause of
action specified, and in furtherance of leis intention it waives and
relinquishes, to the extent permitted by applicable law, all rights and benefits
under any provision of any applicable law that may provide that a general
release does not extend to claims which the person giving the release does not
know or suspect to exist in its favor at the time of executing the release,
which if known by it might have materially affected its settlement with the
recipient of the release. Each Borrower acknowledges that it may hereafter
discover facts different from or in addition to those now known or believed to
be true with respect to such claims, demands, or causes of action and agree that
this instrument shall be and remain effective in all respects notwithstanding
any such differences or additional facts. Each Borrower understands,
acknowledges and agrees that the release set forth above may be pleaded as a
full and complete defense and may be used as a basis for an injunction against
any



                                       5
<PAGE>


action, suit or other proceeding which may be instituted, prosecuted or
attempted in breach of the provisions of such release.

         (b) Each Borrower, on behalf of itself and its successors, assigns, and
other legal representatives, hereby absolutely, unconditionally and irrevocably,
covenants and agrees with and in favor of each Released Party above that it will
not sue (at law, in equity, in any regulatory proceeding or otherwise) any
Released Party on the basis of any claim released, remised and discharged by
such Borrower pursuant to the above release. If any Borrower or any of its
successors, assigns or other legal representations violates the foregoing
covenant, such Borrower, for itself and its successors, assigns and legal
representatives, agrees to pay, in addition to such other damages as any
Released Party may sustain as a result of such violation, all attorneys' fees
and costs incurred by such Released Party as a result of such violation.

     4. Effectiveness of Amendment. Agent must have received this Amendment and
the attached Acknowledgement by Guarantors, each fully executed in a sufficient
number of counterparts for distribution to all parties, before this Amendment is
effective.

     5. Condition Precedent. On or before August 8,2003, with respect to each
contract listed on Schedule E-1 hereto, Agent must have received an Assignment
of Claims, a Notice of Assignment of Claims (executed by the applicable Borrower
but not by the contracting officer or disbursing officer with respect thereto)
and either a Government Contract Certification or a complete copy of such
contract. If such condition is not satisfied within such time frame, the
Borrowing Base shall immediately be recalculated without giving effect to any
Government Accounts with respect to which such documentation has not been
received by Agent.

     6. Representations and Warranties. Each Borrower represents and warrants as
follows:

         (a) Authority. Each Borrower has the requisite corporate power and
authority to execute and deliver this Amendment, and to perform its obligations
hereunder and under the Loan Documents (as amended or modified hereby) to which
it is a party. The execution, delivery and performance by each Borrower of this
Amendment have been duly approved by all necessary corporate action, have
received all necessary governmental approval, if any, and do not contravene any
law or any contractual restrictions binding on each Borrower. No other corporate
proceedings are necessary to consummate such transactions.

         (b) Enforceability. This Amendment has been duly executed and delivered
by the Borrowers. This Amendment and each Financing Agreement (as amended or
modified hereby) is the legal, valid and binding obligation of Borrowers,
enforceable against each Borrower in accordance with its terms, and is in full
force and effect.

         (c) Representations and Warranties. The representations and warranties
contained in each Financing Agreement (other than any such representations or
warranties that, by their terms, are specifically made as of a date other than
the date hereof) are correct on and as of the date hereof as though made on and
as of the date hereof, as modified by any changes to the schedules to the Loan
Agreement reported to the Agent or the Lenders. Parent confirms any



                                       6
<PAGE>


changes in such schedules which are required to be reported to the Agent or the
Lenders under the terms of the Loan Agreement have been reported.

         (d) No Default. After giving effect to the waiver set forth in Section
2 hereof, no event has occurred and is continuing that constitutes an Event of
Default and by entering into this Amendment, except as expressly set forth in
Section 2 hereof, Agent is not waiving and shall not be deemed to have waived
any Event of Default that may exist.

         (e) No Duress. This Amendment has been entered into without force or
duress, of the free will of each Borrower. Each Borrower's decision to enter
into this Amendment is a fully informed decision and such Borrower is aware of
all legal and other ramifications of such decision.

         (f) Counsel. Each Borrower has read and understands this Amendment, has
consulted with and been represented by legal counsel in connection herewith, and
has been advised by its counsel of its rights and obligations hereunder and
thereunder.

     7. Choice of Law. The validity of this Amendment, its construction,
interpretation and enforcement, the rights of the parties hereunder, shall be
determined under, governed by, and construed in accordance with the internal
laws of the State of New York governing contracts only to be performed in that
State.

     8. Counterparts. This Amendment may be executed in any number of
counterparts and by different parties and separate counterparts, each of which
when so executed and delivered, shall be deemed an original, and all of which,
when taken together, shall constitute one and the same instrument. Delivery of
an executed counterpart of a signature page to this Amendment by telefacsimile
shall be effective as delivery of a manually executed counterpart of this
Amendment.

     9. Reference to and Effect on the Loan Documents.

         (a) Upon and after the effectiveness of this Amendment, each reference
in the Loan Agreement to "this Agreement", "hereunder", "hereof" or words of
like import referring to the Loan Agreement, and each reference in the other
Loan Documents to "the Loan Agreement", "thereof" or words of like import
referring to the Loan Agreement, shall mean and be a reference to the Loan
Agreement as modified and amended hereby.

         (b) Except as specifically amended above, the Loan Agreement and all
other Loan Documents, are and shall continue to be in full force and effect and
are hereby in all respects ratified and confirmed and shall constitute the
legal, valid, binding and enforceable obligations of each Borrower to Agent
without defense, offset, claim or contribution.

         (c) The execution, delivery and effectiveness of this Amendment shall
not, except as expressly provided herein, operate as a waiver of any right,
power or remedy of Agent under any of the Loan Documents, nor constitute a
waiver of any provision of any of the Loan Documents.



                                       7
<PAGE>


         (d) To the extent that any terms and conditions in any of the Loan
Documents shall contradict or be in conflict with any terms or conditions of the
Loan Agreement, after giving effect to this Amendment, such terms and conditions
are hereby deemed modified or amended accordingly to reflect the terms and
conditions of the Loan Agreement as modified or amended hereby.

     10. Ratification. Each Borrower hereby restates, ratifies and reaffirms
each and every term and condition set forth in the Loan Agreement, as amended
hereby, and the Loan Documents effective as of the date hereof.

     11. Estoppel. To induce Agent and the Lenders to enter into this Amendment
and to continue to make advances to Borrowers under the Loan Agreement, each
Borrower hereby acknowledges and agrees that no right of offset, defense,
counterclaim or objection in favor of any Borrower as against Agent or any
Lender with respect to the Obligations.

     12. Submission of Amendment. The submission of this Amendment to the
parties or their agents or attorneys for review or signature does not constitute
a commitment by Agent or any Lender to waive any of its rights and remedies
under the Loan Documents, and this Amendment shall have no binding force or
effect until all of the conditions to the effectiveness of this Amendment have
been satisfied as set forth herein.

                       [Signatures follow on next page.]



                                       8
<PAGE>


     IN WITNESS WHEREOF, the parties have entered into this Amendment as of the
date first above written.



                           WELLS FARGO FOOTHILL, INC.,
                           a California corporation,
                           as Agent and as a Lender


                           By: /s/ copy illegible
                               ------------------------------------------------
                           Title: Vice President
                                  ---------------------------------------------


                           ABLECO FINANCE LLC,
                           a Delaware limited liability company,
                           as a Lender


                           By:
                               ------------------------------------------------
                           Title:
                                  ---------------------------------------------


                           MERCURY AIR GROUP, INC.,
                           a Delaware corporation


                           By:
                               ------------------------------------------------
                           Title:
                                  ---------------------------------------------


                           MERCURY AIR CENTERS, INC.,
                           a California corporation


                           By:
                               ------------------------------------------------
                           Title:
                                  ---------------------------------------------


                           MERCURY AIR CARGO, INC.,
                           a California corporation


                           By:
                               ------------------------------------------------
                           Title:
                                  ---------------------------------------------



                                       9
<PAGE>


     IN WITNESS WHEREOF, the parties have entered into this Amendment as of the
date first above written.


                           WELLS FARGO FOOTHILL, INC.,
                           a California corporation,
                           as Agent and as a Lender


                           By:
                               -----------------------------------------------
                           Title:
                                  --------------------------------------------





                           ABLECO FINANCE LLC,
                           a Delaware limited liability company,
                           as a Lender and on behalf of its affiliate assigns


                           By: /s/ (signature illegible)
                               -----------------------------------------------
                           Title: Vice President
                                  --------------------------------------------


                           MERCURY AIR CROUP, INC.,
                           a Delaware corporation


                           By:
                                ----------------------------------------------
                           Title:
                                  --------------------------------------------


                           MERCURY AIR CENTERS,INC.,
                           a California corporation


                           By:
                               -----------------------------------------------
                           Title:
                                  --------------------------------------------



                           MERCURY AIR CARGO, INC.,
                           a California corporation


                           By:
                               -----------------------------------------------
                           Title:
                                  --------------------------------------------



                                       9
<PAGE>


     IN WITNESS WHEREOF, the parties have entered into this Amendment as of the
date first above written.

                           WELLS FARGO FOOTHILL, INC.,
                           a California corporation,
                           as Agent and as a Lender


                           By:
                               ------------------------------------------------
                           Title:
                                  ---------------------------------------------


                           ABLECO FINANCE LLC,
                           a Delaware limited liability company,
                           as a Lender


                           By:
                               ------------------------------------------------
                           Title:
                                  ---------------------------------------------


                           MERCURY AIR GROUP, INC.,
                           a Delaware corporation


                           By: /s/ Joseph A. Czyzyk
                               ------------------------------------------------
                           Title: President & CEO
                                  ---------------------------------------------


                           MERCURY AIR CENTERS, INC.,
                           a California corporation


                           By: /s/ Joseph A. Czyzyk
                               ------------------------------------------------
                           Title: CEO & President
                                  ---------------------------------------------


                           MERCURY AIR CARGO, INC.,
                           a California corporation


                           By: /s/ Joseph A. Czyzyk
                               ------------------------------------------------
                           Title: CEO
                                  ---------------------------------------------



                                       9
<PAGE>


                           MERCFUEL, INC.,
                           a Delaware corporation


                           By: /s/ Joseph A. Czyzyk
                               -----------------------------------------------
                           Title: CEO
                                  --------------------------------------------


                           MAYTAG AIRCRAFT CORPORATION,
                           a Colorado corporation


                           By: /s/ Joseph A. Czyzyk
                               -----------------------------------------------
                           Title: CEO
                                  --------------------------------------------


                           HERMES AVIATION, INC.,
                           a California corporation


                           By: /s/ Joseph A. Czyzyk
                               -----------------------------------------------
                           Title: CEO
                                  --------------------------------------------


                           MERCURY AIR CENTER-BIRMINGHAM, LLC,
                           an Alabama limited liability company


                           By: /s/ Joseph A. Czyzyk
                               -----------------------------------------------
                           Title: President & CEO
                                  --------------------------------------------


                           MERCURY AIR CENTER-BAKERSFIELD, INC.,
                           a California corporation


                           By: /s/ Joseph A. Czyzyk
                               -----------------------------------------------
                           Title: President & CEO
                                  --------------------------------------------
                           MERCURY AIR CENTER-BURBANK, INC.,
                           a California corporation


                           By: /s/ Joseph A. Czyzyk
                               -----------------------------------------------
                           Title: President & CEO
                                  --------------------------------------------


                                       10
<PAGE>
                           MERCURY AIR CENTER-FRESNO, INC.,
                           a California corporation


                           By: /s/ Joseph A. Czyzyk
                               ------------------------------------------------
                           Title: President & CEO
                                  ---------------------------------------------


                           MERCURY AIR CENTER-LOS ANGELES, INC.,
                           a California corporation


                           By: /s/ Joseph A. Czyzyk
                               ------------------------------------------------
                           Title: President & CEO
                                  ---------------------------------------------


                           MERCURY AIR CENTER-ONTARIO, INC.,
                           a California corporation

                           By: /s/ Joseph A. Czyzyk
                               ------------------------------------------------
                           Title: President & CEO
                                  ---------------------------------------------


                           MERCURY AIR CENTER-SANTA BARBARA, INC.,
                           a California corporation


                           By: /s/ Joseph A. Czyzyk
                               ------------------------------------------------
                           Title: President & CEO
                                  ---------------------------------------------


                           MERCURY AIR CENTER-HARTSFIELD, LLC,
                           a Georgia limited liability company


                           By: /s/ Joseph A. Czyzyk
                               ------------------------------------------------
                           Title: President & CEO
                                  ---------------------------------------------



                                       11
<PAGE>


                           MERCURY AIR CENTER-PEACHTREE
                           DEKALB, LLC
                           a Georgia limited liability company


                           By: /s/ Joseph A. Czyzyk
                              ------------------------------------------------
                           Title: President & CEO
                                  --------------------------------------------




                           MERCURY AIR CENTER- FT. WAYNE, LLC,
                           an Indiana limited liability company


                           By: /s/ Joseph A. Czyzyk
                              ------------------------------------------------
                           Title: President & CEO
                                  --------------------------------------------





                           MERCURY AIR CENTER-JACKSON, LLC
                           a Mississippi limited liability company




                           By: /s/ Joseph A. Czyzyk
                              ------------------------------------------------
                           Title: President & CEO
                                  --------------------------------------------



                           MERCURY AIR CENTER-RENO, LLC,
                           a Nevada limited liability company


                           By: /s/ Joseph A. Czyzyk
                              ------------------------------------------------
                           Title: President & CEO
                                  --------------------------------------------

                           MERCURY AIR CENTER-TULSA, LLC.,
                           an Oklahoma limited liability company


                           By: /s/ Joseph A. Czyzyk
                              ------------------------------------------------
                           Title: President & CEO
                                  --------------------------------------------



                           MERCURY AIR CENTER-CHARLESTON, LLC.
                           a South Carolina limited liability company


                           By: /s/ Joseph A. Czyzyk
                              ------------------------------------------------
                           Title: President & CEO
                                  --------------------------------------------



                                       12
<PAGE>


                           MERCURY AIR CENTER-JOHNS ISLAND, LLC.,
                           a South Carolina limited liability company



                           By:  /s/ Joseph A. Czyzyk
                               ------------------------------------------------
                           Title: President & CEO
                                  ---------------------------------------------




                           MERCURY AIR CENTER-NASHVILLE, LLC.,
                           a Delaware limited liability company


                           By:  /s/ Joseph A. Czyzyk
                               ------------------------------------------------
                           Title: President & CEO
                                  ---------------------------------------------




                           MERCURY AIR CENTER-ADDISON, INC.,
                           a Texas corporation

                           By:  /s/ Joseph A. Czyzyk
                               ------------------------------------------------
                           Title: President & CEO
                                  ---------------------------------------------


                           MERCURY AIR CENTER-CORPUS CHRISTI, INC.,
                           a Texas corporation


                           By:  /s/ Joseph A. Czyzyk
                               ------------------------------------------------
                           Title: President & CEO
                                  ---------------------------------------------

                                       13
<PAGE>


                         ACKNOWLEDGEMENT BY GUARANTORS

                           Dated as of August 1, 2003

     Each of the undersigned, being a Guarantor (each a "Guarantor" and
collectively, the "Guarantors") under their respective Guaranty and Security
Agreement, dated December 30, 2002 and made in favor of Agent for the benefit of
the Lenders (each a "Guaranty" and collectively, the "Guaranties"), hereby
acknowledges and agrees to the foregoing Fourth Amendment to Loan and Security
Agreement and Waiver (the "Amendment") and confirms and agrees that its Guaranty
is and shall continue to be, in full force and effect and is hereby ratified and
confirmed in all respects except that, upon the effectiveness of, and on and
after the date of the Amendment, each reference in such Guaranty to the Loan
Agreement (as defined in the Amendment), "thereunder", "thereof" or words of
like import referring to the "Loan Agreement", shall mean and be a reference to
the Loan Agreement as amended or modified by the Amendment. Although Lender has
informed Guarantors of the matters set forth above, and Guarantors have
acknowledged the same, each Guarantor understands and agrees that Lender has no
duty under the Loan Agreement, the Guaranties or any other agreement with either
Guarantor to so notify any Guarantor or to seek such an acknowledgement, and
nothing contained herein is intended to or shall create such a duty as to any
advances or transaction hereafter.

     Each Guarantor hereby absolutely and unconditionally releases and forever
discharges each Released Party, from any and all claims, demands or causes of
action of any kind, nature or description, whether arising in law or equity or
upon contract or tort or under any state or federal law or otherwise, which such
Guarantor has had, now has or has made claim to have against any such person for
or by reason of any act, omission, matter, cause or thing whatsoever arising
from the beginning of time to and including the date hereof, whether such
claims, demands and causes of action are matured or unmatured or known or
unknown. It is the intention of each Guarantor in providing this release that
the same shall be effective as a bar to each and every claim, demand and cause
of action specified, and in furtherance of this intention it waives and
relinquishes, to the extent permitted by applicable law, all rights and benefits
under any provision of any applicable law that may provide that a general
release does not extend to claims which the person giving the release does not
know or suspect to exist in its favor at the time of executing the release,
which if known by it might have materially affected its settlement with the
recipient of the release. Each Guarantor acknowledges that it may hereafter
discover facts different from or in addition to those now known or believed to
be true with respect to such claims, demands, or causes of action and agree that
this instrument shall be and remain effective in all respects notwithstanding
any such differences or additional facts. Each Guarantor understands,
acknowledges and agrees that the release set forth above may be pleaded as a
full and complete defense and may be used as a basis for an injunction against
any action, suit or other proceeding which may be instituted, prosecuted or
attempted in breach of the provisions of such release. Each Guarantor, on behalf
of itself and its successors, assigns, and other legal representatives, hereby
absolutely, unconditionally and irrevocably, covenants and agrees with and in
favor of each Released Party above that it will not sue (at law, in equity, in
any regulatory proceeding or otherwise) any Released Party on the basis of any
claim released, remised and discharged by such Guarantor pursuant to the above
release. If any Guarantor or any of its successors, assigns or other legal
representations violates the foregoing covenant, such Guarantor, for itself and
its successors, assigns and legal representatives, agrees to pay, in addition to
such other damages as



                                       14
<PAGE>


any Released Party may sustain as a result of such violation, all attorneys'
fees and costs incurred by such Released Party as a result of such violation.


                           EXCEL CARGO,INC.,
                           a California corp.


                           By: /s/ Joseph A. Czyzyk
                               -----------------------------------------------
                           Title: CEO


                           VULCAN AVIATION, INC.,
                           a California corporation


                           By: /s/ Joseph A. Czyzyk
                               -----------------------------------------------
                           Title: President & CEO




                           MERCURY ACCEPTANCE CORPORATION,
                           a California corporation


                           By: /s/ Joseph A. Czyzyk
                               -----------------------------------------------
                           Title: President & CEO


                           JUPITER AIRLINE AUTOMATION
                           SERVICES, INC.
                           a Florida corporation


                           By: /s/ Joseph A. Czyzyk
                               -----------------------------------------------
                           Title: CEO

                           AEG FINANCE CORPORATION,
                           a Delaware corporation


                           By: /s/ Joseph A. Czyzyk
                               -----------------------------------------------
                           Title: CEO



                                       15
<PAGE>


                                  EXHIBIT C-2
                   FORM OF GOVERNMENT CONTRACT CERTIFICATION

                           [on Borrower's letterhead]


To:  Wells Fargo Foothill, Inc., as Agent
     2450 Colorado Avenue, Suite 3000 West
     Santa Monica, California 90404
     Attn:_______________________________


        Re: Mercury Air Group, Inc.
            Government Contract Certification Dated_____________________

Ladies and Gentlemen:

     Reference is made to that certain Loan and Security Agreement, dated as of
December 30, 2002 (as amended, modified or supplemented from time to time, the
"Loan Agreement") among Mercury Air Group, Inc. and its Subsidiaries signatory
thereto (collectively, "Borrowers"), the lenders signatory thereto (the
"Lenders"), and Wells Fargo Foothill, Inc., a California corporation, as the
arranger and administrative agent for the Lenders ("Agent"). Capitalized terms
used in this Government Contract Certification have the meanings set forth in
the Loan Agreement unless specifically defined herein.

     Pursuant to the terms of the Loan Agreement, the undersigned, being
the_________ of____________________ (the "Contracting Borrower"), hereby
certifies that he/she is the duly elected and acting____________________ of the
Contracting Borrower, that the Contracting Borrower has entered into a contract
to provide services or goods which may give or have given rise to Government
Accounts (a "Government Contract") and that the following information with
respect to such Government Contract is true, correct and complete:

Contract No:___________________________________________________________

Contract Dated:________________________________________________________

Original Contract Amount: $____________________________________________

Contract's Effective Dates:________________ through____________________

Contracting Agency:____________________________________________________

Name and Address of
Contracting Officer:___________________________________________________

                    ___________________________________________________

                    ___________________________________________________

                    ___________________________________________________

                    Phone:_____________________________________________




                                       16
<PAGE>


Name and Address of
Disbursing Officer:___________________________________________________

                   ___________________________________________________

                   ___________________________________________________

                   ___________________________________________________

                   Phone:_____________________________________________


Contract is not a subcontract:  _________True   __________False

Contract is a:  ______________New Contract
                ______________Extension or Renewal of an Existing Contract

Contracting Parties Have Been Instructed
to Remit Payments to Cash Management Account: __________True   _________False

     The Contracting Borrower hereby requests that Agent and its counsel prepare
an Assignment of Claims and a Notice of Assignment of Claims with respect to
such Government Contract for execution by the Contracting Borrower for purposes
of making the Government Accounts arising from such Government Contract part of
the Borrowing Base.

     IN WITNESS WHEREOF, this Government Contract Certification is executed by
the undersigned this_______ day of____________ ,______.



                           ____________________________________________

                           a___________________________________________



                           By:_________________________________________
                           Name:
                           Title:



                                       17
<PAGE>


                                  SCHEDULE E-1
                     EXISTING GOVERNMENT ACCOUNT CONTRACTS



      Contract No.                                     In Effect Through
      1.  SPO600-97D-5795                                    11/03
      2.  SPO600-98D-5889                                    10/03
      3.  SPO600-00D-5000                                    01/04
      4.  SPO600-00D-5007                                    11/04
      5.  SPO600-00D-5010                                    12/04
      6.  SPO600-00D-5014                                    01/05
      7.  SPO600-01D-5101                                    11/04
      8.  SPO600-01D-5102
      9.  SPO600-02C-5211                                    03/06
      10. F05611-00C-0001                                    01/04
      11. F11626-00C-0104                                    09/03
      12. F11626-03C-0001                                    09/05
      13. F11626-03C-0003                                    09/05
      14. F11626-03C-0004                                    09/05
      15. F11626-03C-0007                                    09/05
      16. DTFA04-03C-20022                                   09/07
      17. DTFA04-03C-20046                                   09/07
      18. DTFA04-03C-20075                                   09/07




                                       18