Originally Posted by
MSPeconomist
It depends on the circumstances. If you'e departing from an outstation where your carrier has no aircraft, with the inbound being delayed but scheduled to arrive be a certain time, you can be pretty confident that your flight will not depart before that time.
+1
That's how I play my nng-sha flights (find the inbound aircraft online and leave for the airport when it's an hour away). Even with this strategy, the inevitable departure delay is still awful, but I typically reduce my total delay by an hour.
However, when flying out of a base city, aircraft substitutions can happen. I almost got burned pretty bad because of this last summer, but saved myself by carrying on all of my heavy bags.