Not automatically. Supervising employees who are neither supervisors, professionals nor managers is first-line supervision, which the statute excludes from managerial capacity unless the person manages an essential function of the organization at a senior level. For a field-service operation, the function branch is usually the honest one.
Choose the branch the facts support, then evidence that branch
The statutory definition offers two doors, and petitions fail when they walk at both without committing to either. Through the personnel door, Étienne would have to show that the people he directs are themselves supervisory, professional or managerial — crew leads with their own reports, or technicians whose roles genuinely require a degree. Through the function door, the question is whether he manages an essential function at a senior level: not whether he is busy, but whether the maintenance programme is a discrete function of the business, whether he sets its policy rather than executing someone else's, and what discretion he holds over budget, method and contract risk.
Evidence differs by door. The personnel branch needs an organizational chart with subordinate qualifications attached. The function branch needs the artefacts of the function itself: the maintenance strategy document, the budget he signs, the performance guarantees he is accountable for, and the decisions he takes without approval.