Upvote:1
The thing about delays is that they are generally estimates; the airline might be able to shorten the delay, or it may turn out to be longer. Sign up for flight status alerts (if offered by the airline) and/or check the flight status yourself regularly to see if the estimated departure time has changed. If the flight still shows the delayed time, plan to be at the airport a little more ahead of the new time than you planned to be ahead of the original time (e.g., if you planned to be there two hours ahead of the original time, I suggest two and a half hours ahead of the new time).
The reality is that you probably will end up waiting at the airport for a long time, since delays often get worse, but sometimes they are shortened.
Upvote:6
For the airlines I'm familiar with, they would say something like "you should be at the airport at 1600 and at the gate at 1730". In other words, the same as if the flight were not delayed.
There is almost always the possibility that the airline will be able to avoid the delay and have the flight leave on time, or with less of a delay than originally predicted. If this happens, and you miss the flight, they are not going to be be very sympathetic.
As an example, here is what Southwest Airlines says:
Since Southwest strives to maintain an ontime schedule, even after we notify you that a flight may be delayed or cancelled, we may substitute or reroute aircraft at the last minute in order to get flights back on the published schedule. Since flight status and gate assignments may change at any time, check airport monitors for the most updated information.
As far as I know, TSA / Homeland Security aren't relevant here; they should let you through security any time up until your plane has actually left (I'm not sure that they even check departure times at all). It's entirely a matter of airline policy.