I'm going to just re-post this as it is. This is a good explanation of what the airlines have to go through when there are disruptions.
Thanks to SH, a United agent, for sharing this with me.
For those unaware of how an airline works, here is a brief overview of how things go down when there is a major disruption to the system. This is why Hurricane Harvey and the flooding in Houston is going to affect your travel plans for several days or longer, regardless of where you are flying in the USA or internationally.
United Airlines and Southwest Airlines have both lost their major hubs in Houston. To make matters worse they have also both lost large pilot and flight attendant bases at both airports.
Why is that important? Not only do these crews work many of the flights into and out of Houston, but more importantly they operate other flights around the system. They are your crew for that flight from Boston to Atlanta, from Ft. Lauderdale to St. Louis, Seattle to Salt Lake City. They might have overnighted in Minneapolis to fly the first flight out to Denver and then to Nashville and many other cities.
These crews are now stuck in Houston — hopefully still at home and not having been displaced by the catastrophic flooding — with no way to an airport that is closed. The crews from Houston that are already out on a multi-day trip are now unable to fly as they have exceeded their legal crew time mandated by the FAA. So they can't pick up trips for these missing crew flights.
To make matters worse, it is the end of the month meaning many other crews in other bases for United and Southwest are, again, illegal and unable to fly any of these missing crew flights.
The FAA and union contracts dictate how much they can fly in a 24-hour period, 7-day period, and per month. Very little wiggle room with these rules.
This is a worse case, nightmare scenario for our crew schedulers and operations folks. There are not enough legal crew members — both pilots and flight attendants — in the other bases to cover the flights the Houston-based crews would operate.
Then, in the case of United which has many different series of aircraft in their fleet, you have to match the crews to the aircraft. A captain on, say, a 737 cannot just move over and be a captain on the 777 where they need a pilot. (Most flight attendants can move to other aircraft but internationally you have additional requirements which some, just not any, crew member can fly.)
So you are going to find both international and domestic flights cancelled. Yes, the weather where you are is nice but there is no legal crew to fly your plane.
So you aren't flying United or Southwest and think this won't affect you? Well, guess who all of those displaced passengers are going to fly on? Your airline.
This is going to have an effect on everyone flying over the next week or so, no matter what route or airline you are flying.
Remember international flights into and out of Bush Intercontinental (IAH) and Hobby (HOU) will not operate for the next few days, and those passengers flying on airlines like British Air, Lufthansa, Air New Zealand, etc., will be rebooked on other international flights to different destinations in the USA. So those flights will be more full than normal, if they have any open seats at all.
Finally, I can assure you that regardless of the airline, the employees are doing their absolute best to get you to your destination, as soon as possible, and as safely as possible.
So if you are flying this week, relax, stop and observe how hard airline staff is working to resolve everyone's dire need to get where they are going. They are doing their best, and your patience and understanding is much appreciated.