Right now, I am taking a class on Air Traffic Management (ATM), which is already yielding some very concrete useful knowledge: unbeknown to me, the FAA and NOAA have a lot of very interesting tools on the web. These web sites may help you to get a better picture of your expected delay; much better than what gets announced at the airport or within the cabin, anyways.
ATCSCC
The Air Trafic Control System Command Center (ATCSCC) is responsible for mananging the entire National Airspace System (NAS). As such, they are in charge of all re-rerouting and have tons of interesting data for travelers. From their web page I can recommend:
- The overview map (by region or airport) on their home page gives you an interactive and easy to interpret view of the current air traffic situation. Clicking on the airport yields a summary of expected delays and their real reason (no more airline babble about that strange gasket that was out of order).
- The Operational Information System has a nice overview about what is going on in the NAS in more detail.
- The airport arrival demand chart tells you what the line for arrivals at the destination looks like. If there is a backup, you will fly happy holding patterns.
- The advisories database has all current ATCSCC advisories, including ground stop (i.e. the reasons for sitting on the tarmac for 3 hours before getting cleared for departure). Note that these advisories are not in clear text, but you need to understand the shorthand.
Finally, you can sign up for an airport delay email notification for the 40 busiest US airports at: http://www.fly.faa.gov/ais/jsp/register.jsp
NOAA
The National Weather Service has an aviation weather site at http://aviationweather.gov/. There are a lot of interesting services there for the avid hobby pilot or flightsimulator nerd, but the CCFP is most interesting from a airline-delay-perspective: it provides a 2h, 4h, and 6h convective pattern forcast (read: bad flying weather). This, and the turbulence charts can tell you at what segment of your trip to expect flying coffee cups (in the best case). Putting everything together, you can install the Flight Path Tool for a rich client GUI.