EXHIBIT 5.1 PARCEL, MAURO & SPAANSTRA, P.C. 1801 CALIFORNIA ST., STE. 3600 DENVER, CO 80202 (303) 292-6400 July 9, 1998 Securities and Exchange Commission Judiciary Plaza 450 Fifth Street, N.W. Washington, D.C. 20549 Re: Frontier Airlines, Inc. Form S-3 Registration Statement Covering 7,452,930 Shares of Common Stock Ladies and Gentlemen: As counsel for Frontier Airlines, Inc., a Colorado corporation (the "Company"), we have examined the above-referenced Registration Statement on Form S-3 under the Securities Act of 1933, as amended (the "Registration Statement"), which the Company has filed covering the sale of 7,452,930 shares of the Company's common stock (the "Shares"). Capitalized terms used and not defined herein shall have the meanings given to them in the Registration Statement. We have examined the Registration Statement, the Company's articles of incorporation and by-laws and the record of its corporate proceedings and have made such other investigation and reviewed such other documents as we have deemed necessary in order to express the opinions set forth below. Based upon the foregoing and upon such further examinations as we have deemed relevant and necessary, we are of the opinion that: 1. The Company is a corporation duly organized and validly existing under the laws of the State of Colorado. 2. The Shares have been legally and validly authorized under the Company's Articles of Incorporation, as amended, and constitute (or will constitute upon due exercise of the warrants to purchase Shares as described in the Registration Statement) duly and validly issued and outstanding and fully paid and nonassessable shares of the Company. Securities and Exchange Commission July 9, 1998 Page 2 We render the foregoing opinion as members of the Bar of the State of Colorado and express no opinion as to laws other than the laws of the State of Colorado and the federal laws of the United States of America. We hereby consent to the use of our name beneath the caption "Legal Matters" in the Prospectus forming a part of the Registration Statement and to the filing of a copy of this opinion as Exhibit 5.1 thereto. PARCEL, MAURO & SPAANSTRA, P.C.