Originally Posted by jpdx

Nobody will know until day of, but generally speaking, Sunday afternoons have been the worst for violent protests in recent weeks (but it is impossible to say where the mayhem will take place and how bad it will be). However, protesters seem to be late risers, and there's rarely any action before noon, so if you were to take the 16:00 flight (and head to the airport around 13:00) you'd in all likelihood be fine. Even with the later flight, you'd probably be fine, as the MTR seems to work hard to keep the Airport Express running from HK station. And there are taxis and bus options. I don't think another complete airport blockade is likely.