Document:

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                                                                     EXHIBIT 4.5

                          WAIVER AND CONSENT AGREEMENT

              WAIVER AND CONSENT AGREEMENT, dated as of July 2, 2001, among
Mercury Air Group, Inc., a New York corporation (the "Company"), J. H. Whitney
Mezzanine Fund, L.P., a Delaware limited partnership ("WMF"), and each of the
corporations which are signatories hereto listed as Guarantors (each a
"Guarantor"). All capitalized terms used herein and not otherwise defined herein
shall have the respective meanings provided such terms in the Purchase Agreement
referred to below.

                              W I T N E S S E T H :

              WHEREAS, the Company and WMF are parties to a Securities Purchase
Agreement, dated as of September 10, 1999 (as amended, modified or supplemented
through the date hereof, the "Purchase Agreement"); and

              WHEREAS, the Company has requested that WMF provide the waiver
provided for herein, and WMF has agreed to provide such waiver on the terms and
conditions set forth herein;

              WHEREAS, the Guarantors are parties to the Guaranty.

              NOW, THEREFORE, it is agreed:

              1. Section 9.6 of the Purchase Agreement limits the Company's
right with respect to Asset Dispositions (as defined in the Purchase Agreement).
The Company has advised WMF that its subsidiary, RPA Airline Automotion
Services, Inc. ("RPA") and RPA's affiliate RPA; Division El Salvador, S.A. de
C.V. ("RPA, S.A., and together with RPA, the "Target Companies"), have agreed to
sell all of the assets of the Target Companies pursuant to that certain Asset
Purchase Agreement (the "Asset Purchase Agreement"), dated the date hereof, by
and among RPA, SITA Information Networking Computing USA Inc., the Company and
RPA, S.A. (the "Disposition"), a copy of which has been provided to WMF. WMF
hereby consents to the Disposition, subject to the satisfaction of each of the
conditions set forth below:

                     (a) the Disposition is consummated in accordance with the
Asset Purchase Agreement in the form delivered to WMF, without amendment,
modification or waiver of any provision without the prior consent of WMF; and

                     (b) the net proceeds received from the Disposition (i.e.,
the Purchase Price less related expenses) are paid to reduce the amount
outstanding under the Term Loan made pursuant to Senior Credit Agreement (as
defined in the Purchase Agreement).

              2. For purposes of the Guaranty, by their respective signatures
below, each Guarantor hereby consents and agrees to the entering into of this
Waiver and Consent Agreement and acknowledges and affirms that the Guaranty (as
amended, modified or supplemented prior to the date hereof) remains in full
force and effect in

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accordance with its terms on the date hereof and after giving effect to this
Waiver and Consent Agreement. The Company and each of the Guarantors hereby
acknowledges and affirms that the Guaranty (as amended, modified or supplemented
prior to the date hereof) remains in full force and effect in accordance with
its terms on the date hereof and after giving effect to this Waiver and Consent
Agreement.

              3. This Waiver and Consent Agreement is limited as specified and
shall not constitute a modification, acceptance or waiver of any other provision
of the Purchase Agreement or any of the other Transaction Documents.

              4. In order to induce WMF to enter into this Waiver and Consent
Agreement, the Company hereby represents and warrants that no default under any
of the Transaction Documents or Event of Default exists as of the date hereof.

              5. This Waiver and Consent Agreement may be executed in any number
of counterparts and by the different parties hereto on separate counterparts,
each of which counterparts when executed and delivered shall be an original, but
all of which shall together constitute one and the same instrument. A complete
set of counterparts shall be delivered to WMF.

              6. THIS WAIVER AND CONSENT AGREEMENT AND THE RIGHTS AND
OBLIGATIONS HEREUNDER SHALL BE GOVERNED BY, CONSTRUED IN ACCORDANCE WITH, AND
ENFORCED UNDER, THE LAW OF THE STATE OF NEW YORK APPLICABLE TO AGREEMENTS OR
INSTRUMENTS ENTERED INTO AND PERFORMED ENTIRELY WITHIN SUCH STATE.

              7. This Waiver and Consent Agreement shall become effective when
each of the Company, the Guarantors and WMF shall have signed a counterpart
hereof (whether the same or different counterparts) and shall have delivered
(including by way of telecopier) the same to WMF at its address listed in the
Purchase Agreement.

              8. The Company will pay all expenses of WMF (including fees,
charges and disbursements of counsel) in connection with this Waiver and Consent
Agreement.

              9. From and after the effective date of this Waiver and Consent
Agreement, all references in the Purchase Agreement and each of the other
Transaction Documents to the Purchase Agreement shall be deemed to be references
to the Purchase Agreement after giving effect to this Waiver and Consent
Agreement.

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<PAGE>   3

              IN WITNESS WHEREOF, each of the parties hereto has caused a
counterpart of this Waiver and Consent Agreement to be duly executed and
delivered as of the date first above written.

                                        MERCURY AIR GROUP, INC.
                                        (A NEW YORK CORPORATION)

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

                                        J. H. WHITNEY MEZZANINE FUND, L.P.

                                        By: Whitney GP, L.L.C.
                                            Its General Partner

                                        By
                                          --------------------------------------
                                            Name:
                                            A Managing Director

GUARANTORS:

MERCFUEL, INC.

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

MAYTAG AIRCRAFT CORPORATION

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

MERCURY AIR CARGO, INC.

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

AEG FINANCE CORPORATION

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

                [SIGNATURE PAGE TO WAIVER AND CONSENT AGREEMENT]

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MERCURY AIR CENTERS, INC.
(F/K/A WOFFORD FLYING SERVICES, INC.)

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

HERMES AVIATION, INC.

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

VULCAN AVIATION, INC.

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

RPA AIRLINE AUTOMATION SERVICES, INC.
(F/K/A RENE PEREZ AND ASSOCIATES, INC.)

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

MERCURY ACCEPTANCE CORPORATION

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

EXCEL CARGO, INC.

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

MERCFUEL, INC.

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

                [SIGNATURE PAGE TO WAIVER AND CONSENT AGREEMENT]

                                       4<PAGE>   1

                                                                     EXHIBIT 4.6

                                WAIVER AGREEMENT

              WAIVER AGREEMENT, dated as of September 25, 2001, among Mercury
Air Group, Inc., a New York corporation (the "Company"), J. H. Whitney Mezzanine
Fund, L.P., a Delaware limited partnership ("WMF"), and each of the corporations
which are signatories hereto listed as Guarantors (each a "Guarantor"). All
capitalized terms used herein and not otherwise defined herein shall have the
respective meanings provided such terms in the Purchase Agreement referred to
below.

                              W I T N E S S E T H :

              WHEREAS, the Company and WMF are parties to a Securities Purchase
Agreement, dated as of September 10, 1999 (as amended, modified or supplemented
through the date hereof, the "Purchase Agreement"); and

              WHEREAS, the Company has requested that WMF provide the waiver
provided for herein, and WMF has agreed to provide such waiver on the terms and
conditions set forth herein;

              WHEREAS, the Guarantors are parties to the Guaranty.

              NOW, THEREFORE, it is agreed:

              1. Pursuant to Section 9.8(a) of the Purchase Agreement, the
Company has agreed that it will not permit Interest Coverage for the Company and
its Subsidiaries, on a consolidated basis, for the twelve-month period ending on
June 30, 2001 to be less than 3.50:1.00. The Company has advised WMF that as for
the twelve month period ended June 30, 2001 Interest Coverage covered for the
Company and its Subsidiaries, on a consolidated basis was 3.22:1.0, and has
requested that WMF waive compliance by the Company with the covenant set forth
in Section 9.8(a). WMF hereby waives compliance by the Company and its
Subsidiaries with the covenant set forth in Section 9.8(a), subject to the
satisfaction of each of the conditions set forth below:

                     (a) delivery to WMF of original counterpart signature pages
of this Waiver Agreement, duly executed and delivered by WMF, the Company, and
each of the Guarantors; and

                     (b) payment by the Company of all fees and expenses of WMF
special counsel in connection with the transaction contemplated by this Waiver
Agreement.

              2. For purposes of the Guaranty, by their respective signatures
below, each Guarantor hereby consents and agrees to the entering into of this
Waiver Agreement and acknowledges and affirms that the Guaranty (as amended,
modified or supplemented prior to the date hereof) remains in full force and
effect in accordance with its terms on the date hereof and after giving effect
to this Waiver Agreement.

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              3. This Waiver Agreement is limited as specified and shall not
constitute a modification, acceptance or waiver of any other provision of the
Purchase Agreement or any of the other Transaction Documents.

              4. In order to induce WMF to enter into this Waiver Agreement, the
Company hereby represents and warrants that no default under any of the
Transaction Documents or Event of Default exists or will exist as of the date
hereof.

              5. This Waiver Agreement may be executed in any number of
counterparts and by the different parties hereto on separate counterparts, each
of which counterparts when executed and delivered shall be an original, but all
of which shall together constitute one and the same instrument. A complete set
of counterparts shall be delivered to WMF.

              6. THIS WAIVER AGREEMENT AND THE RIGHTS AND OBLIGATIONS HEREUNDER
SHALL BE GOVERNED BY, CONSTRUED IN ACCORDANCE WITH, AND ENFORCED UNDER, THE LAW
OF THE STATE OF NEW YORK APPLICABLE TO AGREEMENTS OR INSTRUMENTS ENTERED INTO
AND PERFORMED ENTIRELY WITHIN SUCH STATE.

              7. This Waiver Agreement shall become effective when each of the
Company, the Guarantors and WMF shall have signed a counterpart hereof (whether
the same or different counterparts) and shall have delivered (including by way
of telecopier) the same to WMF at its address listed in the Purchase Agreement.

              8. The Company will pay all expenses of WMF (including fees,
charges and disbursements of counsel) in connection with this Waiver Agreement.

              9. From and after the effective date of this Waiver Agreement, all
references in the Purchase Agreement and each of the other Transaction Documents
to the Purchase Agreement shall be deemed to be references to the Purchase
Agreement after giving effect to this Waiver Agreement.

                           [INTENTIONALLY LEFT BLANK]

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              IN WITNESS WHEREOF, each of the parties hereto has caused a
counterpart of this Waiver Agreement to be duly executed and delivered as of the
date first above written.

                                        MERCURY AIR GROUP, INC.
                                        (A NEW YORK CORPORATION)

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

                                        J. H. WHITNEY MEZZANINE FUND, L.P.

                                        By:  Whitney GP, L.L.C.
                                             Its General Partner

                                        By
                                           -------------------------------------
                                             Name:
                                             A Managing Director

GUARANTORS:

MERCFUEL, INC.

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

MAYTAG AIRCRAFT CORPORATION

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

MERCURY AIR CARGO, INC.

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

AEG FINANCE CORPORATION

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

MERCURY AIR CENTERS, INC.

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(F/K/A WOFFORD FLYING SERVICES, INC.)

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

HERMES AVIATION, INC.

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

VULCAN AVIATION, INC.

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

JUPITER AIRLINE AUTOMATION SERVICES, INC.
(F/K/A RPA AIRLINE AUTOMATION SERVICES, INC.)

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

MERCURY ACCEPTANCE CORPORATION

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

EXCEL CARGO, INC.

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

                      [SIGNATURE PAGE TO WAIVER AGREEMENT]

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