http://www.aircanada.com/en/news/140904_1.html

As a result of the planned Lufthansa labour disruption scheduled between 5pm and 11pm (local Frankfurt time) on September 5, 2014, Air Canada has implemented a policy for customers originally scheduled to travel to, from or via Frankfurt during the affected time period with an Air Canada ticket issued no later than September 4, 2014.

If you are scheduled to travel during the affected time period, you may contact Air Canada Reservations to change your flight free of charge, to another date between September 6 and December 5, 2014, subject to availability. Please note, however, that any fare difference will apply.