I got to work again this afternoon, this time on the Assistant desk working on some support tasks rather than dispatching flights. This desk on this day gave me a prime seat to watch but not endure one of the worst possible weather situations: a line of thunderstorms moving through the Northeast. One of my worst days ever came on a day just like this. We deal with thunderstorms all spring and summer in various parts of the country, but the Northeast is special.

1. It’s the busiest airspace in the world. It is the launch point for hundreds of flights each day to all parts of the US plus many to Canada, Asia, Europe, and Central and South America.
2. It’s a fairly narrow strip of land bordered by a huge ocean on one side, with a limited number of routes available, and Canada on the other with its own air traffic control system.
3. Because it’s so busy, it has four different air traffic control “centers”, which manage traffic above a certain altitude, plus a huge number of other ATC facilities that manage traffic landing at or departing the many airports and metropolitan areas. People at all these different facilities have to work together to feed each other traffic.

Until we switch to a satellite-based ATC/navigation system, we must continue to fly generally from point to point using ground-based radio beacons that form “highways in the sky” called airways. For busy airports like many in the Northeast, ATC, the FAA, and the airport work together to design set pathways in and out. These pathways help the controllers to ensure that aircraft maintain a safe distance from each other. When a line of thunderstorms moves through an area like the Northeast, it shuts off these pathways, forcing inbound flights to hold and departing flights to sit and wait until the storms move far enough away from the pathways to make them safe to fly again. Where able, ATC moves flights from one pathway to another as the storms move through. It’s like a wreck that occurs on LBJ and shuts down a line or even the whole freeway until emergency crews can get it cleared out. Maybe there’s an alternate route, but maybe you’re stuck. It all depends.

The pilots, dispatchers, and ground personnel for an airline are trying to react to the weather and ATC’s instructions and also to predict them. Since weather is so fluid, and ATC is made of people who have their own experiences and perspectives, accurately predicting the actions of either factor is challenging.

Today, for example, the line of storms first hit Baltimore, one of our biggest airports, causing several diversions that had to sit and wait for a while at their diversion airports until the weather passed and the three Washington, D.C.-area airports got their airborne traffic cleaned up. But by then the line had moved to the northeast, hitting Philadelphia and cutting off New England from the rest of the country. The diversions finally got to land in Baltimore, but any flight trying to reach New England from Baltimore was stopped by ATC because there weren’t enough open airways to handle all the traffic. Imagine shutting down LBJ, I-30, and I-35 simultaneously. The whole area ground to a halt, and the phones started ringing more and more – pilots frustrated because ATC won’t let them launch, ground personnel who had more planes to handle than places to park them, not to mention lots of unhappy passengers.

Since we couldn’t launch many of our flights from Baltimore, we had to start holding our flights on the ground in other cities that were headed toward Baltimore because we didn’t have any available gates. Situations like this are often difficult for passengers to understand because they don’t have the big picture – the weather is great in Nashville and Baltimore, so why are we delayed for two hours?!? My hat is off to the customer service agents, pilots, and flight attendants who have to explain situations like these to our passengers.

Further complicating matters, the various ATC facilities are negotiating among themselves regarding when to open and close the available airspace as the weather moves. For example, Boston Center might tell New York TRACON that they can accept traffic spaced 15 miles apart on just one airway, but New York TRACON might only be willing to space the traffic 20 miles apart (more wiggle room around the storms) and might want to switch traffic to a different airway in 30 minutes because they think the weather will move by then. As they make decisions, the updated plans slowly feed down to the pilots and dispatchers, who then have to decide how to react. Do we need more fuel for the new route? Do we concur that it’s safe? Often the dispatcher what seems like a good route, but ATC won’t accept it because of factors that he/she cannot see. Situations like this are very complicated and frustrating all around because there is no perfect solution. We just do the best we can with the circumstances we’re given, just like you do.

I hope this post gives you some insight into both my job and your own flying experience if you ever deal with weather-related delays. I assure you that we never WANT your flight to be delayed, but for any number of reasons, it’s sometimes necessary. If the weather were always perfect, and every aircraft always worked perfectly, and the airlines collectively scheduled their flights to match the capacity of each airport, every airline could run close to 100 percent. But until those beautiful events work out, we’ll sometimes have to deal with days like today.