This news is a little late. However, AIC 21/08 fills us in:
TORONTO/BUTTONVILLE, ONTARIO REDUCTION IN THE CONTROL TOWER HOURS OF OPERATIONS
NAV CANADA, the country’s provider of civil air navigation services, recently conducted an aeronautical study that reviewed the hours of operation of the control tower at the Toronto/Buttonville airport.
Taking into consideration the complexity, level, and nature of operations, NAV CANADA concluded that reducing the hours of the control tower by one hour would not adversely affect the safety or efficiency of flight operations.
Currently the hours of operation for the control tower at the Toronto/Buttonville Airport are 0600h to 2300h local time. As a result of this study, the hours of operation will be amended to 0700h to 2300h local time.
This change will take effect 5 June 2008 at 09:01 Coordinated Universal Time. The appropriate aeronautical publications will be amended. For further information, please contact:
Marcel Pinon Manager, Level of Service & Aeronautical Studies – East NAV CANADA 77 Metcalfe Street Ottawa, ON K1P 5L6
Those tower guys deserve an extra hour of sleep ;)