News release from Transport Canada:
As a result of a terrorist incident on Northwest Flight 253 from Amsterdam to Detroit on December 25, 2009, additional security measures were put in place at Canada’s airports for flights to the United States.
On December 28, Transport Canada put in place enhanced security measures for passengers on flights bound for the United States. Effective immediately, US bound passengers are not allowed to bring carry on bags into the cabin of the aircraft, with some exceptions. Passengers may carry with them the following items: medication or medical devices, small purses, cameras, coats, items for care of infants, laptop computers, crutches, canes, walkers, containers carrying life sustaining items, a special needs item, musical instruments, or diplomatic or consular bags.
Transport Canada also has authorized the Canadian Air Transport Security Authority (CATSA) to use RCMP and local police officers to actively assist with some procedures specific to the screening process.
The purpose of this is to alleviate the immediate pressures at the security checkpoint resulting directly from the temporary emergency measures announced by Transport Canada on December 26th.
Additional searches of passengers and their exempted items will continue. Delays can be expected so passengers are advised to arrive at the airport three hours in advance of their scheduled flight. — www.tc.gc.ca