Following the events of September 11, 2001, the employer implemented shift work for Regional Security Inspectors (RSIs) employed at international airports - RSIs are responsible for safety and security at airports, as well as railways and harbours - the RSIs were previously considered day workers - the employer first contacted the bargaining agent at the national level at the beginning of October, and the first consultation meeting took place on October 26, 2001 - discussions continued between the parties but no agreement was reached - during discussions in October, the bargaining agent raised the issue of pending grievances and the employer sent a letter to the bargaining agent agreeing to suspend the time limits for filing a grievance until completion of the consultation process - a joint memorandum announcing the agreement to suspend the time limits was prepared but never finalized - the grievances in issue were filed in March and April of 2002 - the employer argued that the grievances should only be retroactive to 25 days prior to the filing of the grievances and should not be given full retroactive effect - the Board held that the agreement was clear and that the grievances should have full retroactive effect - the bargaining agent filed a section 99 reference, alleging that the employer had breached clause 25.04 of the collective agreement in failing to come to an agreement with it on the change in hours of work - the “test grievances” that were also the subject of this decision contested the change in the hours of work and the consequent failure of the employer to pay overtime for hours worked outside the normal day work hours - the grievors were hired on the understanding that they would work as day workers and argued that this was a term and condition of employment - the employer responded that clause 25.04 did not apply to the transition from day work to shift work and argued that clause 25.02 was the applicable clause and required only discussion between the parties, which discussion had taken place - the Board concluded that neither clause 25.02 nor clause 25.04 applied - the Board found that clause 25.04 did not govern a change of hours of work that has the effect of changing a day worker into a shift worker - clause 25.02 did not apply, as it only applied to a change in the “schedule of working hours”, which is the distribution of hours within a fixed period and does not cover the transformation of day workers into shift workers - prior Board decisions and a decision of the Federal Court lead to the conclusion that the employer can transform day workers into shift workers without the agreement of the bargaining agent - management rights prevail, as the collective agreement does not restrict the right of the employer to determine the hours of work and change a day worker to a shift worker.