Lease Amendment
                          (Airport Plaza Office Lease)

This Lease  Amendment,  dated as of April 1, 2000,  is by and  between  Highline
Group Rimfire 25, Inc. ("Landlord"),  as receiver for the Airport Plaza Building
(the "Building") and Frontier Airlines, Inc. ("Tenant").


                                    Recitals

A.       Landlord predecessor and Tenant entered into the Lease Agreement, dated
         March 15, 1994, as amended from time to time (the "Lease").
B.       Landlord and Tenant desire to modify the Lease as set forth below.

                                    Agreement

         Now, therefore,  for good and valuable  consideration,  the receipt and
sufficiency  of  which is  hereby  acknowledged,  the  parties  hereto  agree as
follows:

1.       Tenant hereby leases from Landlord Suites 600b (* square feet) and 600c
         (* square feet).
2.       The  minimum  rent  payable monthly under the Lease for Suites 600b and
         600c, collectively, shall be: $*.  Tenant's  base  year for Suites 600b
         and 600c shall be the year 2000.
3.       The  expiration of the term of the Lease for Suites 600b and 600c shall
         be *.


To the extent that any term of this Lease Amendment shall conflict with any term
in the Lease, or any amendment or term sheet related thereto,  the terms of this
Lease Amendment shall supercede such  conflicting  term and this Lease Amendment
shall control.  Except as modified  herein all of the other terms and conditions
of the Lease shall remain unchanged and in full force and effect.

Landlord
Rimfire 25, Inc.
By: Highline Group LLC, as agent

By:______________________
     Name:_______________
    Title:_______________

Tenant
Frontier Airlines, Inc.

By:______________________
     Name:_______________
    Title:_______________