Possible Clues:

• Mynarski and Beurling org.
• Ottawa-based fliers: Abbr
• Org. involved in NORAD
• Acronym of interest to veterans
• Billy Bishop's org
• Canadian Mil. org
• Can.. military. org
• Org. with bases in Moose Jaw and Goose Bay
• Military org. with the motto 'Per ardua ad astra'