8-K

QuickLinks -- Click here to rapidly navigate through this document

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)
of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): August 23, 2004

Frontier Airlines, Inc.
(Exact name of registrant as specified in its charter)

Colorado	0-24126	84-1256945
(State of Incorporation)	(Commission File Number)	(I.R.S. Employer Identification No.)
7001 Tower Road, Denver, Colorado		80249
(Address of principal executive offices)		(Zip Code)

(720) 374-4200
(Registrant's telephone number)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2.):

o

Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

o

Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

o

Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

o

Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 3.03. Material Modifications to Rights of Security Holders.

        On August 23, 2004, the Board of Directors of Frontier Airlines, Inc. ("Frontier") approved an amendment to the Frontier Airlines, Inc. Rights Agreement dated as of February 20, 1997, as amended (the "Rights Agreement") to (i) remove the requirement that a majority of the Continuing Directors (as defined in the Rights Agreement) approve the redemption of the Rights (as defined in the Rights Agreement) in certain circumstances, and (ii) remove the requirement that the Continuing Directors determine that the value of securities to be exchanged for the Rights under Section 24(c) of the Rights Agreement provides equal value to the market price of Frontier's Common Stock. The Fifth Amendment to Rights Agreement is attached hereto as Exhibit 4.4.E.

Item 9.01 Financial Statements and Exhibits.

        Exhibit 4.4.E. Fifth Amendment to Rights Agreement dated August 23, 2004.

2

SIGNATURE

        Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

	FRONTIER AIRLINES, INC.
Date: August 24, 2004	By:	/s/  JEFF S. POTTER
	Its:	President and CEO
	By:	/s/  PAUL H. TATE
	Its:	CFO

3

QuickLinks

Item 3.03. Material Modifications to Rights of Security Holders.
Item 9.01 Financial Statements and Exhibits.

SIGNATURE

EX-4.4

QuickLinks -- Click here to rapidly navigate through this document

EXHIBIT 4.4.E

FIFTH AMENDMENT TO
RIGHTS AGREEMENT

        THIS FIFTH AMENDMENT TO RIGHTS AGREEMENT (this "Fifth Amendment") is made and entered into as of this [            ] day of August, 2004, by and between FRONTIER AIRLINES, INC. (the "Company") and MELLON INVESTOR SERVICES as Rights Agent (the "Rights Agent").

Recitals

        A.    The Company and American Securities Transfer & Trust, Inc., predecessor in interest to the Rights Agent, entered into a Rights Agreement dated as of February 20, 1997 (as amended, the "Rights Agreement"); and

        B.    The Board of Directors of the Company, by resolution duly adopted on August 23, 2004, authorized this Fifth Amendment to the Rights Agreement.

Agreement

        The Company and the Rights Agent hereby amend the Rights Agreement as follows:

        1.     Section 23(a) of the Rights Agreement is hereby amended in its entirety to read as follows:

        (a)   The Board of Directors of the Company may, at its option, at any time prior to the earlier of (x) such time as a Person becomes an Acquiring Person or (y) the Close of Business on the Final Expiration Date, redeem all but not less than all of the then outstanding Rights at a redemption price of $.01 per Right, appropriately adjusted to reflect any stock split, stock dividend or similar transaction occurring after the date of this Agreement (such redemption price being hereinafter referred to as the "Redemption Price"). The redemption of the Rights by the Board of Directors of the Company may be made effective at such time and on such basis and with such conditions as the Board of Directors of the Company in its sole discretion may establish. Except for the obligation to pay the Redemption Price, the Board of Directors and the Company shall not have any liability to any Person as a result of the redemption of Rights pursuant to the terms of this Section 23. Notwithstanding anything in this Agreement to the contrary, the Rights shall not be exercisable at any time when the Company may redeem them pursuant to this Section 23. The Company may, at its option, pay the Redemption Price in cash, shares of Common Stock (based on the "current market price," as defined in Section 11(d) hereof, of the Common Stock at the time of redemption) or any other form of consideration deemed appropriate by the Board of Directors.

        2.     Section 24(c) of the Rights Agreement is hereby amended in its entirety to read as follows:

        (c)   In the event that there shall not be sufficient unreserved shares of Common Stock issued but not outstanding or authorized, unissued and unreserved to permit the exchange of Rights as contemplated in accordance with this Section 24, the Company, at its option, may substitute shares of equivalent stock, as such term is defined in Section 11(b), or common stock equivalents, as such term is defined in Section 11(a)(iii)(3)(C), for shares of Common Stock exchangeable for Rights, at the initial rate of one share of equivalent stock or one common stock equivalent for each share of Common Stock, as appropriately adjusted to reflect stock splits, stock dividends or similar transactions affecting the Common Stock that occur after the date of this Agreement.

        3.     The remainder of the Rights Agreement shall remain unchanged, and the Rights Agreement as amended above, shall remain in full force and effect.

        IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be fully executed on their behalf as of the date first above written.

FRONTIER AIRLINES, INC.

By:

Name:

Title:

MELLON INVESTOR SERVICES

By:

Name:

Title:

2

QuickLinks

FIFTH AMENDMENT TO RIGHTS AGREEMENT