<PAGE>
                                                                EXHIBIT 4.9
________________________________________________________________________________

                                VALUJET, INC.,

                    THE SUBSIDIARY GUARANTORS NAMED HEREIN,
                                 as Guarantors

                                      and

                             FLEET NATIONAL BANK,
                                 successor to
                  BANK OF MONTREAL TRUST COMPANY, as Trustee

                             ____________________

                         First Supplemental Indenture

                          Dated as of August 26, 1996

                                      to

                                   Indenture

                          Dated as of April 17, 1996

                             ____________________

                                 $150,000,000


                         10 1/4% Senior Notes due 2001

________________________________________________________________________________
<PAGE>

<PAGE>

                         FIRST SUPPLEMENTAL INDENTURE

     THIS FIRST SUPPLEMENTAL INDENTURE (this "SUPPLEMENTAL INDENTURE"), dated as
of August 26, 1996, is among ValuJet, Inc., a Nevada corporation (the
"COMPANY"), each of the Subsidiary Guarantors (as hereinafter defined), Bank of
Montreal Trust Company, a New York corporation (the "RESIGNING TRUSTEE"), and
Fleet National Bank, a national banking association (the "SUCCESSOR TRUSTEE").
All terms used herein but not defined herein shall have the meanings assigned to
such terms in that certain Indenture dated as of April 17, 1996, relating to the
Company's 10 1/4% Senior Notes due 2001 (the "INDENTURE").

                                   RECITALS

     A.   The Company and the Resigning Trustee executed the Indenture as of
April 17, 1996.

     B.   On July 17, 1996 (the "RESIGNATION NOTICE DATE"), the Resigning
Trustee gave written notice, as required by Section 610 of the Indenture, to the
Company of its resignation as Trustee under the Indenture, such resignation to
become effective upon the acceptance of appointment by a successor Trustee under
Section 611 of the Indenture.

     C.   The parties hereto have entered into that certain Agreement of
Resignation, Appointment and Acceptance dated as of the date hereof (the
"RESIGNATION AGREEMENT"), pursuant to which, among other things, (i) the Company
agrees to accept the resignation of the Resigning Trustee, as Trustee, and (ii)
the Company appoints, as of the date of execution of the Resignation Agreement
and this Supplemental Indenture by all parties thereto and hereto, the Successor
Trustee as Trustee under the Indenture.

     D.   The parties hereto desire to execute this Supplemental Indenture to
(i) provide for the substitution of the Successor Trustee as Trustee under the
Indenture pursuant to the Resignation Agreement, (ii) provide for the
substitution of the Successor Trustee as Security Registrar and Paying Agent
under the Indenture, and (iii) amend certain provisions of the Indenture in
connection with such substitution as hereinafter set forth.

     NOW, THEREFORE, THIS SUPPLEMENTAL INDENTURE WITNESSETH, the Company, the
Subsidiary Guarantors (as defined in the Indenture, the "SUBSIDIARY
GUARANTORS"), Resigning Trustee and Successor Trustee mutually covenant and
agree for the equal and proportionate benefit of all Holders as follows:

                                  ARTICLE ONE

                            Amendment of Indenture
                            ----------------------

     Section 1.1    Amendment of Certain Sections of Indenture
                    ------------------------------------------

                                       1
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     (a)  The introductory paragraph of the Indenture is hereby deleted in its
entirety and substituted in lieu thereof with the following:


          "INDENTURE, dated as of April 17, 1996, among VALUJET, INC., a
          corporation duly organized and existing under the laws of the State of
          Nevada (herein called the "Company"), having its principal office at
          1800 Phoenix Boulevard, Suite 126, Atlanta Georgia 30349, each of the
          SUBSIDIARY GUARANTORS (as hereinafter defined) and FLEET NATIONAL
          BANK, a national banking association, as Trustee (herein called the
          "Trustee").

     (b)  The definition of the term "Corporate Trust Office" in Section 101 of
the Indenture is hereby deleted in its entirety and substituted in lieu thereof
with the following:

          "Corporate Trust Office" means an office of the Trustee in New York,
          New York or Boston, Massachusetts, at which at any time its corporate
          trust business shall be administered."

     (c)  Subparagraph (1) of Section 105 of the Indenture is hereby deleted in
its entirety and substituted in lieu thereof with the following:

          "(1)      the Trustee by any Holder or by the Company or any
          Subsidiary Guarantor shall be sufficient for every purpose hereunder
          if made, given, furnished or filed in writing to or with the Trustee
          at its Corporate Trust Office, Attention: Corporate Trust Department,
          or any other address previously furnished in writing to the Holders or
          the Company by the Trustee, or, with respect to notices by the Company
          or any Subsidiary Guarantor, transmitted by facsimile transmission
          (confirmed by overnight courier) to the following facsimile numbers:
          (617) 346-5501 or (617) 346-5502 or to any other facsimile number
          previously furnished in writing to the Company by the Trustee, or"

Except as amended by this Section 1.1(c), all other provisions of Section 105
                          --------------
of the Indenture shall remain in full force and effect.

     (d)  The first sentence of Section 609 of the Indenture is hereby deleted
in its entirety and substituted in lieu thereof with the following:

          "There shall at all times be a Trustee hereunder which shall be a
          Person that is eligible pursuant to the Trust Indenture Act to act as
          such, has a combined capital and surplus of at least $10,000,000 and
          has its Corporate Trust Office located in the Borough of Manhattan,
          The City of New York, or in The City of Boston, the Commonwealth of
          Massachusetts; provided, however, that if the Corporate Trust Office
                         --------  -------
          is located in the City of Boston,

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          the Trustee shall maintain an office or agency in the Borough of
          Manhattan, The City of New York, for purposes of performing its
          obligations as Trustee hereunder."

Except as amended by this Section 1.1(d), all other provisions of Section 609 of
                          --------------
the Indenture shall remain in full force and effect.

     (e)  The first paragraph of Section 1002 of the Indenture is hereby deleted
in its entirety and substituted in lieu thereof with the following:

          "The Company will maintain in the Borough of Manhattan, the City of
          New York, an office or agency where Securities may be presented or
          surrendered for payment, where Securities may be surrendered for
          registration of transfer or exchange and where notices and demands to
          or upon the Company or any Subsidiary Guarantor in respect of the
          Securities, the Subsidiary Guarantees and this Indenture may be
          served. The Company will give prompt written notice to the Trustee of
          the location, and any change in the location, of such office or
          agency. If at any time the Company shall fail to maintain any such
          required office or agency or shall fail to furnish the Trustee with
          the address thereof, such presentations, surrenders, notices and
          demands may be made or served at the Corporate Trust Office of the
          Trustee (provided, however, that if the Corporate Trust Office is
                   --------  -------
          located in the City of Boston, the State of Massachusetts, such
          presentations, surrenders, notices and demands may be made or served
          at the office or agency of the Trustee located in the Borough of
          Manhattan, the City of New York), and the Company and each Subsidiary
          Guarantor hereby appoints the Trustee as its agent to receive all such
          presentations, surrenders, notices and demands."

The second paragraph of Section 1002 of the Indenture is hereby deleted in its
entirety and substituted in lieu thereof with the following:

          "The Company may also from time to time designate one or more other
offices or agencies (in or outside the Borough of Manhattan, the City of New
York) where the Securities may be presented or surrendered for any and all such
purposes and may from time to time rescind such designations; provided, however,
                                                              --------  -------
that no such designation or rescission shall in any manner relieve the Company
of its obligation to maintain an office or agency in the Borough of Manhattan,
the City of New York, for such purposes. The Company will give prompt written
notice to the Trustee of any such designation or rescission and of any change in
the location of any such other office or agency."

Except as amended by this Section 1.1(e), all other provisions of Section 1002
                          --------------
of the Indenture shall remain in full force and effect.

                                       3
<PAGE>

                                  ARTICLE TWO

     Section 2.1  Resignation.  The Resigning Trustee hereby resigns as
                  -----------
Trustee under the Indenture, and the Company hereby accepts such resignation.

     Section 2.2  Appointment and Acceptance. As of the close of business on the
                  --------------------------
date hereof, the Company hereby appoints the Successor Trustee as Trustee under
the Indenture with all of the rights, powers and duties heretofore vested in the
Resigning Trustee, as Trustee under the Indenture, and the Successor Trustee
hereby acknowledges and accepts such appointment.

     Section 2.3  Transfer.  Pursuant to Section 611 of the Indenture, the
                  --------
Resigning Trustee hereby transfers to the Successor Trustee all the rights,
powers and trusts of the Resigning Trustee and hereby assigns, transfers and
delivers to the Successor Trustee all property and money held by the Resigning
Trustee under the Indenture.

     Section 2.4  Confirmation.  Pursuant to Section 611 of the Indenture, (i)
                  ------------
the Company and the Subsidiary Guarantors hereby confirm that the Successor
Trustee is vested with all rights, powers and trusts of the Trustee under the
Indenture, and (ii) upon the request of the Successor Trustee, the Company and
the Subsidiary Guarantors shall execute any and all instruments for more fully
and certainly vesting in and confirming to the Successor Trustee all such
rights, powers and trusts.

     Section 2.5  Notice.  Pursuant to Section 610(f) of the Indenture, the
                  ------
Company shall give notice of the resignation of the Resigning Trustee and the
appointment of the Successor Trustee to all Holders in the manner provided in
Section 106 of the Indenture. Such notice shall include the name of the
Successor Trustee and the address of its Corporate Trust Office. The Resigning
Trustee shall, within five (5) business days of the execution of this
Supplemental Indenture, provide the Company with a list of all Holders.

                                 ARTICLE THREE

     Section 3.1 Resignation. The Resigning Trustee hereby resigns as Security
                 -----------
Registrar and Paying Agent under the Indenture, and the Company hereby accepts
such resignation.

     Section 3.2  Appointment and Acceptance.  As of the close of business on
                  --------------------------
the date hereof, the Company hereby appoints the Successor Trustee as Security
Registrar for the purpose of registering Securities and transfers and exchanges
of Securities as provided in the Indenture, and as Paying Agent under the
Indenture, with all of the rights, powers and duties heretofore vested in the
Resigning Trustee, as Security Registrar and Paying Agent under the Indenture,
and the Successor Trustee hereby accepts such appointments.

     Section 3.3  Confirmation. The Company and the Subsidiary Guarantors
                  ------------
hereby confirm that (i) the Successor Trustee is vested with all rights, powers
and trusts of the Registrar and the Paying Agent under the Indenture, and (ii)
upon the request of the Successor Trustee, the

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Company and the Subsidiary Guarantors shall execute any and all instruments for
more fully and certainly vesting in and confirming to the Successor Trustee all
such rights, powers and trusts.

                                 ARTICLE FOUR

                           Miscellaneous Provisions
                           ------------------------

     Section 4.1    Counterparts. This Supplemental Indenture may be executed in
                    ------------
counterparts, each of which when so executed shall be deemed to be an original,
but all such counterparts shall together constitute one and the same instrument.

     Section 4.2    Severability. In the event that any provision in this
                    ------------
Supplemental Indenture shall be invalid, illegal or unenforceable, the validity,
legality and enforceability of the remaining provisions shall not in any way be
affected or impaired thereby.

     Section 4.3    Headings. The article and section headings herein are for
                    --------
convenience only and shall not affect the construction hereof.

     Section 4.4    Successors and Assigns. All the covenants, stipulations,
                    ----------------------
promises and agreements in this Supplemental Indenture by or on behalf of the
Company or the Trustee shall bind such party's respective successors and
assigns, whether so expressed or not.

     Section 4.5    Governing Law. THIS SUPPLEMENTAL INDENTURE SHALL BE GOVERNED
                    -------------
BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK, AS
APPLIED TO CONTRACTS MADE AND PERFORMED WITHIN THE STATE OF NEW YORK, WITHOUT
REGARD TO PRINCIPLES OF CONFLICTS OF LAWS.

     Section 4.6    Effect of Supplemental Indenture. Except as amended by this
                    --------------------------------
Supplemental Indenture, the terms and provisions of the Indenture shall remain
in full force and effect.

     Section 4.7    Trustee. The Resigning Trustee and the Successor Trustee
                    -------
accept the modifications of trusts referenced in the Indenture and effected by
this Supplemental Indenture. Without limiting the generality of the foregoing,
neither the Resigning Trustee nor the Successor Trustee assumes any
responsibility for the correctness of the recitals herein contained, which shall
be taken as the statements of the Company, and neither the Resigning Trustee nor
the Successor Trustee shall be responsible or accountable in any way whatsoever
for or with respect to the validity or execution or sufficiency of this
Supplemental Indenture, and neither the Resigning Trustee nor the Successor
Trustee makes any representation with respect thereto.

                    Remainder of this Page Intentionally Left Blank

                                       5
<PAGE>

     IN WITNESS WHEREOF, the parties hereto have caused this agreement to be
duly executed and their respective corporate seals to be hereunto duly affixed
and attested by their respective officers thereunto duly authorized, all as of
the day and year first above written.

(Corporate Seal)

Attest:                                     VALUJET, INC.
                                             as the Company


_________________________                   By:  _______________________________
                                                 Name:
                                                 Title:

Attest:                                     VALUJET AIRLINES, INC.,
                                             as Subsidiary Guarantor


_________________________                   By:  _______________________________
Name:                                            Name:__________________________
Title:                                           Title:_________________________


Attest:                                     VALUJET MANAGEMENT CORP.,
                                             as Subsidiary Guarantor


_________________________                   By:  _______________________________
Name:                                            Name:__________________________
Title:                                           Title:_________________________

                                       6
<PAGE>

Attest:                                     VALUJET INVESTMENT CORP.,
                                            as Subsidiary Guarantor


____________________________                By:________________________________
Name:                                          Name:____________________________
Title:                                         Title:___________________________


Attest:                                     VALUJET CAPITAL CORP.,
                                            as Subsidiary Guarantor


____________________________                By:_________________________________
Name:                                          Name:____________________________
Title:                                         Title:___________________________



Attest:                                     VALUJET CORPORATE PARTNERS, L.P.,
                                             as Subsidiary Guarantor

                                            By:  VALUJET MANAGEMENT CORP.,
                                                 its General Partner


____________________________                By:_________________________________
Name:                                          Name:____________________________
Title:                                         Title:___________________________

                                       7
<PAGE>

Attest:                                     VALUJET RESERVATION PARTNERS, L.P.,
                                             as Subsidiary Guarantor

                                            By:  VALUJET MANAGEMENT CORP.,
                                                 its General Partner


____________________________                By:_________________________________
Name:                                          Name:____________________________
Title:                                         Title:___________________________


                                            VALUJET I, LTD.,
                                             as Subsidiary Guarantor


                                            By:_________________________________
                                               Name:____________________________
                                               Title:___________________________


                                            VALUJET II, LTD.,
                                             as Subsidiary Guarantor


                                            By:_________________________________
                                               Name:____________________________
                                               Title:___________________________

                                       8
<PAGE>

Attest:                                     BANK OF MONTREAL TRUST COMPANY,
                                             as Resigning Trustee


_________________________                   By:_________________________________
Name:                                          Name:____________________________
Title:                                         Title:___________________________


Attest:                                     FLEET NATIONAL BANK,
                                             as Successor Trustee


_________________________                   By:_________________________________
Name:                                          Name:____________________________
Title:                                         Title:___________________________

                                       9
<PAGE>

STATE OF          )
COUNTY OF         ) ss.

     On this the ______ day of August, 1996, before me, the undersigned officer,
personally appeared, ________________________, who acknowledged himself/herself
to be the _____________ of VALUJET, INC., a Nevada corporation, and that he, as
such officer, being authorized so to do, executed the foregoing instrument for
purposes therein contained as his and its free act and deed, by signing the name
of the corporation by himself as such of officer.


     In witness whereof I hereunto set my hand.



                                                   _____________________________
                                                   Notary Public
                                                   My Commission Expires: ______


STATE OF          )
COUNTY OF         ) ss.

     On this the ______ day of August, 1996, before me, the undesigned officer,
personally appeared, ______________________, who acknowledged himself/herself to
be the ______________ of VALUEJET AIRLINES, INC., a Nevada corporation, and that
he, as such officer, being authorized so to do, executed the foregoing
instrument for purposes therein contained as his and its free act and deed, by
signing the name of the corporation by himself as such of officer.


     In witness whereof I hereunto set my hand.


                                                   _____________________________
                                                   Notary Public
                                                   My Commission Expires: ______

                                       10
<PAGE>

STATE OF          )
COUNTY OF         ) ss.

     On this the ______ day of August, 1996, before me, the undersigned officer,
personally appeared, ________________________, who acknowledged himself/herself
to be the _____________ of VALUJET, MANAGEMENT CORP., a Nevada corporation, and
that he, as such officer, being authorized so to do, executed the foregoing
instrument for purposes therein contained as his and its free act and deed, by
signing the name of the corporation by himself as such of officer.


     In witness whereof I hereunto set my hand.



                                                   _____________________________
                                                   Notary Public
                                                   My Commission Expires: ______


STATE OF          )
COUNTY OF         ) ss.


     On this the ______ day of August, 1996, before me, the undesigned officer,
personally appeared, ______________________, who acknowledged himself/herself to
be the ______________ of VALUEJET INVESTMENT CORP., a Nevada corporation, and
that he, as such officer, being authorized so to do, executed the foregoing
instrument for purposes therein contained as his and its free act and deed, by
signing the name of the corporation by himself as such of officer.


     In witness whereof I hereunto set my hand.


                                                   _____________________________
                                                   Notary Public
                                                   My Commission Expires: ______

                                      11
<PAGE>

STATE OF          )
COUNTY OF         ) ss.

     On this the ______ day of August, 1996, before me, the undersigned officer,
personally appeared, ________________________, who acknowledged himself/herself
to be the _____________ of VALUJET, CAPITAL CORP., a Nevada corporation, and
that he, as such officer, being authorized so to do, executed the foregoing
instrument for purposes therein contained as his and its free act and deed, by
signing the name of the corporation by himself as such of officer.


     In witness whereof I hereunto set my hand.



                                                   _____________________________
                                                   Notary Public
                                                   My Commission Expires: ______


STATE OF          )
COUNTY OF         ) ss.


     On this the ______ day of August, 1996, before me, the undesigned officer,
personally appeared, ______________________, who acknowledged himself/herself to
be the ______________ of VALUEJET I, LTD., a Nevada corporation, and that
he, as such officer, being authorized so to do, executed the foregoing
instrument for purposes therein contained as his and its free act and deed, by
signing the name of the corporation by himself as such of officer.


     In witness whereof I hereunto set my hand.


                                                   _____________________________
                                                   Notary Public
                                                   My Commission Expires: ______

                                      12
<PAGE>

STATE OF          )
COUNTY OF         ) ss.

     On this the ______ day of August, 1996, before me, the undersigned officer,
personally appeared, ________________________, who acknowledged himself/herself
to be the _____________ of VALUJET, II, LTD., a Nevada corporation, and that he,
as such officer, being authorized so to do, executed the foregoing instrument
for purposes therein contained as his and its free act and deed, by signing the
name of the corporation by himself as such of officer.


     In witness whereof I hereunto set my hand.



                                                   _____________________________
                                                   Notary Public
                                                   My Commission Expires: ______


STATE OF          )
COUNTY OF         ) ss.


     On this the ______ day of August, 1996, before me, the undesigned officer,
personally appeared, ______________________, who acknowledged himself/herself to
be the ______________ of BANK OF MONTREAL TRUST COMPANY, a New York corporation,
and that he, as such officer, being authorized so to do, executed the foregoing
instrument for purposes therein contained as his and its free act and deed, by
signing the name of the corporation by himself as such of officer.


     In witness whereof I hereunto set my hand.


                                                   _____________________________
                                                   Notary Public
                                                   My Commission Expires: ______

                                      13
<PAGE>

STATE OF          )
COUNTY OF         ) ss:

    On this the _______ day of August, 1996, before me, the undersigned officer,
personally appeared, _______________________________, who acknowledged
himself/herself to be the _________________ of FLEET NATIONAL BANK, a National
Banking Association, and that he, as such officer, being authorized so to do,
executed the foregoing instrument for purposes therein contained as his and its
free act and deed, by signing the name of the corporation by himself as such of
officer.

    In witness whereof I hereunto set my hand.


                                                 _______________________________
                                                 Notary Public
                                                 My Commission Expires: ________

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