EXHIBIT 5.1

                       [LETTERHEAD OF FAEGRE & BENSON LLP]

                                 August 25, 2000

Board of Directors
Frontier Airlines, Inc.
12015 East 47th Avenue
Denver, Colorado 80239

RE:      Post Effective Amendment No. 1 to Form S-3

Ladies and Gentlemen:

         In connection with the Post Effective  Amendment No. 1 on Form S-3 (the
"Registration  Statement")  under the  Securities  Act  relating  to the sale of
3,132,329  shares of common stock (the  "Shares") of Frontier  Airlines  Inc., a
Colorado  corporation  (the "Company"),  we have examined the Company's  charter
documents and the corporate  proceedings taken by the Company in connection with
the issuance and sale of the Shares. Based on this review, we are of the opinion
that:

1.   The Company is duly and validly organized and existing and in good standing
     under the laws of the State of Colorado.

2.   The Shares which may be issued will be, upon issuance,  validly issued, and
     outstanding and fully paid and nonassessable.

         We  consent  to  the  filing  of  this  opinion  as an  exhibit  to the
Registration Statement.

         This  opinion is  rendered  as of the date first  written  above and we
disclaim  any  obligation  to advise  you of facts,  circumstances,  events,  or
developments  which  hereafter  may be  brought to our  attention  and which may
alter,  affect, or modify the opinion expressed herein. Our opinion is expressly
limited to the  matters  set forth  above and we render no  opinion,  whether by
implication or otherwise, as to any other matters relating to the Company or the
Shares.

                               FAEGRE & BENSON LLP

                             /s/ FAEGRE & BENSON LLP




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