The United States’ attention has been focused on Texas and Louisiana in the wake of Hurricane Harvey. I want to spend a few moments on the subject of Hurricane Harvey Houston Air Travel — it has had a major effect.
Houston ranks behind only New York, Los Angeles, and Chicago in total population. Houston is home to two large airports: Houston Hobby and George Bush Intercontinental. Similar to Washington DC where Ronald Reagan National Airport lies closer to downtown, but smaller in operation – Houston Hobby is the equivalent. Similarly Washington Dulles, a good distance from the center of DC, is a much larger airport as is George Bush Intercontinental in Houston.
By volume, George Bush is the 12th busiest airport in the United States with over 43,000 passengers flying into, out of, and through the facility each year. Houston Hobby ranks 3rd on the Medium Airport List with over 12,000 passengers. With the closing of both airports, there are a lot of individuals not getting on airplanes right now.
George Bush Intercontinental Airport
Houston serves as a hub for four airlines. So many individuals flying into Houston do not count Houston as their final destination; rather it is a transition stop to get to their final destination. All those flights now have to be redirected or re-routed. To take out Houston is like taking out a major artery in the body. It can cripple and overload the rest of the system.
Hundreds of flights go in and out of Houston every day. Using a conservative estimate of 100 individuals on each flight and that is thousands of passengers a day affected by the closure. Having to redirect that number of individuals can be staggering, Jay Ratliff, the aviation expert reports the reverberations of the closure are felt in flight traffic in both Mexico and Canada.
But it is not just an issue for the air. Think of the effect on the airport itself and the effort required to get it up and running again.
Runways/taxiways
One of the major issues is the tarmac. The ramps, taxiways and runways over which the aircraft move upon the ground. Covered by torrential rains, they likely are covered with mud and/or sediment. Loose gravel, dirt/clumps etc. can be sucked up into turbofan engines causing damage to the engine blades. The items sucked up are called foreign objects, the damage it causes is called foreign object damage or FOD. FOD is the arch enemy of ground operations. There will be a ton of work to clear the runways and taxiways and ramps of FOD. It usually requires humans walking line abreast picking up every loose object they can find – it is called a FOD walk and it is labor intensive.
Equipment Houston Hobby Airport 
Think of the tugs used at the airport. They pull the baggage carts and tow the airplanes. I imagine most of them were sitting out during the storm and flooding, they don’t generally have garages for these sorts of things, nor enough hangar space. Sand, grit and mud floating through the engines of these tugs, will likely cause huge problems in getting them up and running again. Planes may have fared better assuming they were able to cover the engines, but the slats and flats on the wings will have to be inspected for objects lodged between their massive cracks.
Terminal
This is the least likely of the worries, but given the amount of rain and the normally dry conditions of Houston, the terminal will need to be inspected for structural damage before hundreds of passengers and workers exert their loads upon the structure.
Personnel
There’s an old saying, “matches don’t start forest fires, people do”. I want to modify that phrase and say, “airplanes don’t make airports work, people do”. Consider the hundreds of individuals who work at the two Houston airports. Better yet, consider Brandon. Brandon is a 33 year old tug driver with a wife and two kids. His house in Houston has been flooded out. The drywall is not dry, rather it is molding after being soaked with a couple of feet of water. There is no electricity and little running water. His wife is a stay at home mom with an elementary student and a pre-schooler who can’t go to school because the school is closed.
The last thing that Brandon is thinking about is work, unless it is to call in to use his sick leave and personal leave to get his home back in order.
Brandon is fictitious, but the dozens of employees he represents are not. Just getting the personnel back to work will be a major feat. Not just Brandon the tug driver, but Bob the pilot, Jordan the flight attendant, Frank the mechanic, Bailey the bag handler, etc.
As we say in Doctor Aviation, Session 10. A Large Airport is a city unto itself. Houston has two cities within the city struggling mightily to get back up in the air.
For some FAA statistics on air travel see: https://www.faa.gov/airports/planning_capacity/passenger_allcargo_stats/passenger/media/cy15-commercial-service-enplanements.pdf