Actually, as it turns out, the Rule 240 has been phased out over the years, as the carriers are no longer required by regulation to maintain one. http://www.sm

Actually, as it turns out, the Rule 240 has been phased out over the years, as the carriers are no longer required by regulation to maintain one. http://www.smartertravel.com/travel-advice/rule-240-fading-fast.html?id=2350024 http://www.smartertravel.com/travel-advice/rule-240-fading-f... And, ultimately, you should look in the detailed "contract of carriage" on the airline website (or on the back of your paper ticket, if you have one) to see what the airline's obligations truly are. Also, "weather" can happen anywhere in the country and still affect your flight, even it's not where you're traveling. If your flight requires an aircraft that is arriving from another city where there is a weather problem, or even if there was a weather problem earlier in your city and now the backlog of flights is greater than the number of arrivals and departures that an airport can handle, the delays can stack up over multiple cities. The airlines can't afford to keep equipment (and crew!) buffers at each airport to absorb these delays.