Major-General St-Amand joined the Canadian Forces on 12 June 1981. He graduated from the Royal Military College of Canada, Kingston,
Ontario, with a degree in Electrical Engineering in 1986. He then proceeded through pilot training and completed the advanced fighter Pilot course on the CF-18 in the fall of 1988.
He served as an operational fighter pilot with 433 Tactical Fighter Squadron, 3 Wing Bagotville, Quebec, from 1989 to 1992 and then as an Instructor and Operational Test and Evaluation pilot with 410 Squadron, Cold Lake, Alta, until the summer of 1999.
Major-General St-Amand attended the Canadian Forces Command Staff College, Toronto, Ontario in 1999, after which he was posted to the Directorate Aerospace Requirements 5 (Fighters and Trainers) at National Defense Headquarters (NDHQ), Ottawa. Promoted to Lieutenant-Colonel in 2001, he took over the responsibilities of Project Director for CF-18 Modernization.
In 2003, Major-General St-Amand took command of 441 Tactical Fighter Squadron, Cold Lake, Alta. He attended the USAF Air War College in Montgomery, Al. in 2005 where he was promoted to the rank of Colonel. In 2006, he was posted to Ottawa as the Combined Forces Air Component Commander - Forward. In 2007, Major-General St-Amand assumed command of 4 Wing Cold Lake, Alta., after which he was appointed the Senior Advisor to the Chief of the Defense Staff in 2009. In January 2010, he was promoted to the rank of Brigadier-General and appointed Director Strategic Plans, NATO headquarters, SHAPE Casteau, Belgium. In July 2011, Major-General St-Amand was appointed to the position of Deputy Commander, 1 Canadian Air Division (1 CAD) in Winnipeg, Manitoba.
Major-General St-Amand has flown over 2600 hours in fighter aircraft and participated in Operation NOBLE EAGLE and Northern Sovereignty Operations. While at SHAPE, he directed strategic planning for NATO's intervention in support of the 2010 Pakistani floods, and for NATO's OPERATION UNIFIED PROTECTOR in Libya. He holds a Masters degree in Strategic Studies and a certificate of Practitioner of Joint Warfare from the USAF Air University.
In September 2012, Major-General St-Amand was promoted to his current rank and assumed command of 1 Canadian Air Division/Canadian NORAD Region in Winnipeg, Manitoba.