UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 2)*

(Name of Issuer)

(Title of Class of Securities)

(CUSIP Number)

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

(Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.  ¨

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See §240.13d-7 for other parties to whom copies are to be sent.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

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This Amendment No. 2 (the “Amendment”) amends and supplements the Schedule 13D filed on June 13, 2011, as amended by Amendment No. 1 to the Schedule 13D filed on December 7, 2011 (the “Amended Schedule 13D” and, as supplemented and amended by this Amendment, the “Schedule 13D”) with respect to the Shares of the Issuer. Capitalized terms used in this Amendment and not otherwise defined shall have the same meanings ascribed to them in the Amended Schedule 13D.

Item 2 of the Amended Schedule 13D is hereby amended and supplemented by deleting paragraphs (a) and (c) in their entirety and replacing them with the following.

(a) This statement is filed by (i) Indigo Florida L.P., a Cayman Islands exempt limited partnership (“Indigo Florida”), (ii) Long Bar Miramar LLC, a Delaware limited liability company (“Long Bar Miramar”) and (iii) William A. Franke (“Mr. Franke,” and together with Long Bar Miramar and Indigo Florida, the “Reporting Persons”). The Reporting Persons are filing this statement jointly pursuant to a Joint Filing Agreement attached hereto as Exhibit 1.

(c) Mr. Franke is the Managing Partner of Indigo Partners LLC, a private equity fund focused on investments in the air transportation industry with a principal business address of 2525 E. Camelback Road, Suite 900, Phoenix, Arizona 85016. None of Indigo Florida, Long Bar Miramar and the Related Persons has significant independent business operations and each of them is an investment entity affiliated with and managed by Indigo Partners LLC.

Item 3 of the Original Schedule 13D is hereby amended and supplemented by adding the following paragraph:

On January 25, 2012, Indigo Florida and Long Bar Miramar sold 2,955,898 and 211,136 Shares, respectively, in the Offering (defined below), as described in Item 5 below.

Item 4 of the Amended Schedule 13D is hereby amended and supplemented by inserting the following paragraph.

The Reporting Persons are subject to certain restrictions on the transfer of their Shares as described under “Lock-Up Agreement” in Item 6.

Item 5 of the Amended Schedule 13D is hereby amended and restates Item 5 in its entirety as follows.

(a), (b) To the knowledge of the Reporting Persons, as of January 6, 2012, there are 72,522,541 voting and non-voting Shares issued and outstanding. Indigo Florida and Long Bar Miramar, comprising a “group” within the meaning of Section 13(d)(3) of the Exchange Act of 1934, beneficially own in the aggregate 12,070,920 Shares, comprised of 11,266,193 Shares beneficially owned by Indigo Florida and 804,727 Shares beneficially owned by Long Bar Miramar. Indigo Florida beneficially owns 15.5%^† and Long Bar Miramar beneficially owns 1.1%^†, of the total outstanding Shares. Indigo Pacific Partners LLC is the sole member of Indigo Pacific Capital LLC, which is the general partner of Indigo Pacific Management LP, which is the general partner of Indigo Florida. Indigo Management LLC is the manager of Long Bar Miramar. Mr. Franke, a member of the Issuer’s board of directors, is a managing member of Indigo Pacific Partners LLC and a manager of Indigo Management LLC and has sole voting

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and dispositive power over the Shares held by Indigo Florida and Long Bar Miramar. Mr. Franke disclaims beneficial ownership of the Shares owned by Indigo Florida and Long Bar Miramar except to the extent of any pecuniary interest therein, and disclaims membership in a “group” with Indigo Florida and Long Bar Miramar. Nothing herein shall constitute an admission that any of the executive officers and directors of the Reporting Persons beneficially owns any Shares, and the executive officers and directors of the Reporting Persons disclaim beneficial ownership of any Shares except to the extent of any pecuniary interest therein.

In addition, certain of the Oaktree Funds, which previously comprised a “group” with Indigo Florida and Long Bar Miramar as a result of the Stockholders Agreement that was terminated in accordance with its terms as described in Item 6 below, own in the aggregate 13,017,261 Shares. The Oaktree Funds beneficially own in the aggregate approximately 17.95%^† of the total outstanding Shares.

The holder of each Share is entitled to one vote with respect to such Share on all matters submitted to a vote of the Issuer’s stockholders, including the election of directors.

(c) On January 25, 2012, Indigo Florida and Long Bar Miramar, certain of the Oaktree Funds and certain executive officers of the Issuer sold Shares of the Issuer in a secondary public offering (the “Offering”) pursuant to an effective registration statement on Form S-1 filed on December 6, 2011, as amended on December 22, 2011, January 17, 2012 and January 18, 2012 (the “Registration Statement”). Indigo Florida and Long Bar Miramar sold 2,955,898 and 211,136 Shares, respectively, in the Offering, pursuant to the terms of the Underwriting Agreement described in Item 6 below. Each of the Reporting Persons entered into Lock-Up Agreements (as defined below), as described in Item 6 below. Other than the transactions described above and in Item 3 of the Amended Schedule 13D, none of the Reporting Persons nor, to the knowledge of any of the Reporting Persons, any of the executive officers and directors of the Reporting Persons, has effected any transaction involving the Issuer’s Common Stock during the last 60 days from the date hereof.

(d) Each of Indigo Florida and Long Bar Miramar is an investment entity ultimately controlled by an entity under the control of Mr. Franke, but in respect of which certain other investors hold passive investment interests. No other person is known to have the right to receive or the power to direct the receipt of dividends, or the proceeds from the sale of, the Shares beneficially owned by the Reporting Persons and identified herein with respect to more than 5% of the Shares of the Issuer, except, with respect to Indigo Florida, limited partnership interests in Indigo Pacific Partners, L.P. owned by Havelock Fund Investments Pte. Ltd.

(e) Not applicable.

Item 6 of the Amended Schedule 13D is hereby amended and supplemented by deleting the sections entitled “Registration Statement” and “Stockholder Agreement” in their entirety and adding the following paragraphs.

Fourth Amendment to Second Amended and Restated Investor Rights Agreement

On January 13, 2012, a Fourth Amendment to Second Amended and Restated Investor Rights Agreement was entered into by and among the Issuer, Indigo Florida, Long Bar Miramar, the Oaktree Funds and certain other investors of the Issuer named therein, providing for, among other things, the elimination of restrictions on demand registrations and the re-prioritization of securities to be included in demand registrations.

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Underwriting Agreement

On January 19, 2012 Indigo Florida and Long Bar Miramar entered into an underwriting agreement (the “Underwriting Agreement”) with Barclays Capital Inc., Morgan Stanley & Co. LLC, and Citigroup Global Markets Inc., as representatives of the several underwriters (the “Underwriters”), the Issuer and the selling stockholders listed in Schedule I (together with Indigo Florida and Long Bar Miramar, the “Selling Shareholders”) for the sale by the Selling Shareholders of an aggregate of 11,000,000 Shares, and at the election of the Underwriters, up to 1,650,000 additional Shares to cover overallotments.

Lock-Up Agreement

Each of the Reporting Persons has entered into a Lock-Up Agreement with the Underwriters for a period of 60 days from January 19, 2012 (each, a “Lock-Up Agreement”). Pursuant to the Lock-Up Agreements, each of the Reporting Persons will not, without the prior written consent of the Underwriters and subject to certain exceptions, offer, sell, contract to sell, pledge or otherwise dispose of any shares of capital stock of the Issuer or any securities convertible into, or exercisable or exchangeable for, such capital stock. A form of the Lock-Up Agreement is attached hereto as Exhibit 8 and incorporated herein by reference.

Stockholders Agreement

The Stockholders Agreement, entered into by Indigo Florida as of June 1, 2011 (the “Stockholders Agreement”), with certain of the Oaktree Funds and the Issuer terminated on January 25, 2012 in accordance with its terms, because Indigo Florida and the Oaktree Funds’ aggregate ownership of the Issuer’s capital stock entitled to vote in the election of the Issuer’s directors fell below a majority of the outstanding capital stock entitled to so vote as a result of the Offering.

Item 7 of the Amended Schedule 13D is hereby amended and supplemented by deleting Exhibit 1 in its entirety and adding the following Exhibits.

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Signature

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this Statement is true, complete and correct.

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Exhibit 1

JOINT FILING AGREEMENT

PURSUANT TO RULE 13D-1(K)(1)

The undersigned acknowledge and agree that the foregoing statement on Schedule 13D is filed on behalf of each of the undersigned and that all subsequent amendments to this statement on Schedule 13D shall be filed on behalf of each of the undersigned without the necessity of filing additional joint acquisition statements. The undersigned acknowledge that each shall be responsible for the timely filing of such amendments, and for the completeness and accuracy of the information concerning him or it contained therein, but shall not be responsible for the completeness and accuracy of the information concerning the other, except to the extent that it knows or has reason to believe that such information is inaccurate.

Exhibit 8

Spirit Airlines, Inc.

Public Offering of Common Stock

                , 2011

Barclays Capital Inc.

Citigroup Global Markets Inc.

Morgan Stanley & Co. LLC

As Representatives of the several Underwriters,

c/o Barclays Capital Inc.

745 Seventh Avenue

New York, New York 10019

c/o Citigroup Global Markets Inc.

388 Greenwich Street

New York, New York 10013

c/o Morgan Stanley & Co. LLC

1585 Broadway

New York, New York 10036

Ladies and Gentlemen:

This letter is being delivered to you in connection with the proposed Underwriting Agreement (the “Underwriting Agreement”), between Spirit Airlines, Inc., a Delaware corporation (the “Company”), certain selling stockholders and each of you as representatives of a group of Underwriters named therein, relating to an underwritten public offering of Common Stock, $0.0001 par value (the “Common Stock”), of the Company.

In order to induce you and the other Underwriters to enter into the Underwriting Agreement, the undersigned will not, without the prior written consent of Barclays Capital Inc., Citigroup Global Markets Inc. and Morgan Stanley & Co. LLC, offer, sell, contract to sell, pledge or otherwise dispose of, (or enter into any transaction which is designed to, or might reasonably be expected to, result in the disposition (whether by actual disposition or effective economic disposition due to cash settlement or otherwise) by the undersigned or any affiliate of the undersigned or any person in privity with the undersigned or any affiliate of the undersigned), directly or indirectly, including the filing (or participation in the filing) of a registration statement with the Securities and Exchange Commission in respect of, or establish or increase a put equivalent position or liquidate or decrease a call equivalent position within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”) and the rules and regulations of the Securities and Exchange Commission promulgated thereunder with respect to, any shares of capital stock of the Company or any securities convertible into, or exercisable or exchangeable for such capital stock, or publicly announce an intention to effect any such transaction, for a period of 60 days after the date of the Underwriting Agreement (the “lock-up period”).

If (i) the Company issues an earnings release or material news, or a material event relating to the Company occurs, during the last 17 days of the lock-up period, or (ii) prior to the expiration of the lock-up period, the Company announces that it will release earnings results during the 16-day period beginning on the last day of the lock-up period, the restrictions imposed by this agreement shall continue to apply until the expiration of the 18-day period beginning on the issuance of the earnings release or the occurrence of the material news or material event, unless Barclays Capital Inc., Citigroup Global Markets Inc. and Morgan Stanley & Co. LLC waive, in writing, such extension. The undersigned hereby acknowledges that the Company has agreed in the Underwriting Agreement to provide written notice of any event that would result in an extension of the Lock-Up Period and agrees that any such notice properly delivered will be deemed to have given to, and received by, the undersigned.

Notwithstanding the foregoing, the undersigned may transfer shares of Common Stock (or any securities convertible into, exercisable for, or exchangeable for Common Stock) (i) as a bona fide gift or gifts, provided that the donee or donees thereof agree to be bound in writing by the restrictions set forth herein, (ii) to any trust for the direct or indirect benefit of the undersigned or the immediate family of the undersigned, provided that the trustee of the trust agrees to be bound in writing by the restrictions set forth herein, and provided further that any such transfer shall not involve a disposition for value, (iii) to any third party granted an interest in the undersigned’s will or under the laws of descent, provided that such grantee agrees to be bound in writing by the restrictions set forth herein, (iv) in transactions relating to shares of Common Stock acquired by the undersigned in open market transactions after the completion of this offering, provided that no filings (other than a filing on Form 5 made after the expiration of the lock-up period) by any party under the Exchange Act shall be required or shall be voluntarily made in connection with such transaction, (v) if the undersigned is a corporation, business trust, association, limited liability company, partnership, limited liability partnership or other entity (individually, an “Entity”), to any Entity which is directly or indirectly controlled by, or is under common control with, the undersigned, provided that it shall be a condition to the transfer that the transferee execute an agreement stating that the transferee is receiving and holding such securities subject to the provisions of this lock-up agreement and there shall be no further transfer of such securities except in accordance with this lock-up agreement, and provided further that any such transfer shall not involve a disposition for value, or (vi) dispositions to the Company, during the lock-up period, by the undersigned of shares of Common Stock for the purpose of raising proceeds to cover the reasonably estimated U.S. federal or state tax liability incurred by the undersigned as a result of the vesting, during the lock-up period, of restricted shares of Common Stock heretofore granted to the undersigned, provided each such disposition shall occur on or about the time of such vesting and shall be of an amount of shares of Common Stock that raises gross proceeds that, as nearly as reasonably practicable, approximate such tax liability. In addition, the undersigned shall, during the lock-up period, be entitled to establish a 10b5-1 plan for the sale of shares of Common Stock pursuant to the terms and conditions of such plan, provided that no sale of shares of Common Stock under such plan shall be allowed until after the expiration of the lock-up period and the establishment of such plan does not require or result in any public announcement being made during the lock-up period.

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For purposes of this lock-up agreement, “immediate family” shall mean any relationship by blood, marriage or adoption, not more remote than first cousin.

If the Company notifies you in writing that it does not intend to proceed with the Offering or for any reason the Underwriting Agreement shall be terminated prior to the Closing Date (as defined in the Underwriting Agreement), this agreement shall likewise be terminated.

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