The Snowbirds from the Canadian Forces 431 Air Demonstration Squadron will help celebrate North American Aerospace Defense Command's 60th anniversary with flyovers Friday and Saturday. Canada's military aerobatics team will fly over Peterson Air Force Base at about 2:30 p.m. May 11 and 10:40 a.m. May 12. The team will also fly over Cheyenne Mountain Air Force Station about 3:30 p.m.