FOR IMMEDIATE RELEASE Contact: Dave Thomas, VP Marketing and Planning

       (307) 432-7000

Great Lakes Airlines To Upgrade Equipment Between Sheridan, Wyoming and Denver, Colorado Beginning July 1, 2004

CHEYENNE, Wyo., June 17, 2004 � Great Lakes Aviation, Ltd. (OTC Bulletin Board: GLUX.OB � news) today announced that beginning July 1, 2004, it will upgrade its schedule of flights between Denver International Airport and Sheridan, Wyoming, operating two round trips with the 30 seat EMB-120 Brasilia aircraft. This cabin class aircraft offers flight attendants and lavatories for the non-stop trip to and from Denver.

�Great Lakes is pleased to offer this increase in capacity for Sheridan during the busy summer months,� said Dave Thomas, VP of Marketing and Planning of Great Lakes.  �By increasing the equipment size Great Lakes operates, along with our increased weekend frequency, more summer visitors can enjoy the convenience of flying into Sheridan.�

All flights are timed to make convenient connections with flights scheduled by United Airlines and Frontier Airlines from Denver.

Sheridan � Denver Flight Schedule (Effective July 1, 2004)

Sheridan to Denver:

Flight 5152* Departs  6:00am Arrives   7:25am    Operates Daily

Flight 5156 Departs 11:20am Arrives 12:53pm    Operates Daily

Flight 5150* Departs   3:50pm Arrives  5:15pm     Operates Daily

Flight 5154 Departs  5:26pm Arrives  6:59pm     Operates Sunday Only

Denver � Sheridan Flight Schedule (Effective July 1, 2004)

Denver to Sheridan:

Flight 5156  Departs   9:25am Arrives 10:48am    Operates Daily

Flight 5153* Departs   1:55pm Arrives  3:20pm     Operates Daily

Flight 5154 Departs  3:40pm Arrives  5:16pm     Operates Sunday Only

Flight 5151* Departs   6:05pm Arrives  7:30pm     Operates Saturday Only

Flight 5154* Departs   6:55pm Arrives  8:20pm     Operates Monday-Friday

Flight 5151* Departs   8:15pm Arrives  9:40pm     Operates Sunday Only

* = Will operate in EMB-120 Brasilia Equipment

Great Lakes is providing scheduled passenger service at 37 airports in 10 states with a fleet of Embraer EMB-120 Brasilia and Raytheon/Beech 1900D Regional Airliners.  A total of 174 weekday flights are scheduled at three hubs, with 164 flights at Denver, 4 flights at Minneapolis/St. Paul, and 6 flights at Phoenix. All scheduled flights are operated under the Great Lakes Airlines marketing identity in conjunction with code-share agreements with Frontier Airlines and United Airlines at their Denver hub.

Additional information is available on the company web site that may be accessed at www.greatlakesav.com