Be careful on the AC to YYZ. Several flights depend on inbound from YYZ to arrive on time. A lot of folks missed TATL connection today at YYZ on AC738 due to AC737 departing 2 hours late from YYZ (originally scheduled at 8am, did not leave until 10am), and the ripple effect applied to the return flight from SFO (did not arrive until after 10pm). The later scheduled flight from SFO to YYZ (AC756) departed and arrived before AC738.