SWAP

June 27, 2013 by Bruce Landsberg

storm radarBefore we leave the convective weather topic for a while, think about the emphasis the airlines put into staying out of big, sparky clouds. As you can see from the graphic, there was a lot of weather approaching the DC area from the west on Monday afternoon.

I ‘d committed to a Tuesday morning presentation in Milwaukee, and one needs to allow extra time in convective season whether flying GA or on the airlines because the airspace can turn ugly on almost any afternoon. A gate hold was put into effect for my flight that was scheduled for a 1400 departure. At 1600 we left the gate, and at about 1700 the flight launched toward the line of weather. The delay was not because the Boeing 737 couldn’t avoid the weather on its own but rather that the system could not handle 30 or so flights all headed westbound and all working through the same hole. (Tell me again how NextGen is going to resolve this.) It was a nice ride with only some light turbulence.

Here is a definition of the Severe Weather Avoidance Plan (SWAP) from the National Weather Service Center Weather Service Unit in New York: 

“When an isolated convective cell initiates, an aircraft may be able to deviate around it or fly over the top of it. However, when multiple cells develop and organize into clusters or lines, jet routes in the path of these storms are forced to close. Aircraft using these routes must deviate to other routes. A SWAP is implemented when a significant number of routes are either closed or forecast to close, thus lowering the capacity of the National Airspace System (NAS).”

The Collaborative Convective Forecast Product (CCFP) leaves little doubt as to where the weather was and that the tops, at FL390, were above what most light GA aircraft could tackle. Think about how much teamwork and planning goes into running the system. It should be clear that scheduling is clearly secondary to safety. It’s a lesson some GA pilots should learn.

Looking speculatively at the situation above, there are several reasonable options. An end run to the south might work, assuming the line did not build much farther down that way. It would be at least an hour (or more) detour in most low-altitude light aircraft, but it would keep one out of the cluster—which is a good place not to be.

The second option is to merely wait a few hours until the line passes. That creates other opportunities for difficulty such as more storms forming or darkness, as night approaches.

The third option, which is my favorite in summertime flying, is to go early in the day which eliminates much of the storm problem in the first place. The idea is to be on the ground by early afternoon. That’s not always possible and there are early morning storms, but it’s one of the most reliable strategies.

Option four is simply to cancel, and sometimes that’s the best choice. As we’ve said many times, there is no place one has to be.

Maybe all of us should develop a SWAP strategy. The pros do it.

We hope you were able to catch our Thunderstorms Avoidance webinar last week. Be sure to check out the other products from the Air Safety Institute to help keep you out of harm’s way, such as the Thunderstorms and ATC (requires Flash player) online course, our Thunderstorm Avoidance safety quiz, and our Accident Case Study: Time Lapse. These products are funded by donations to the AOPA Foundation. If you like what you see, please consider a donation today.

Bruce Landsberg
President, AOPA Foundation

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4 Responses to “SWAP”

  1. David Jack Kenny Says:

    If going around the weather doesn’t look feasible, I just wait it out.

  2. pranesh Says:

    Hi Bruce,
    I’m having difficulty locating your column on the redesigned AOPA website. I cannot find it anywhere on the home page.

  3. Bruce Landsberg Says:

    Pranesh…..

    It’s in the News and Video menu at top of the website under Publications, and then “Archives by Article Column.

    http://www.aopa.org/News-and-Video/Pilot-Magazine-Columns.aspx

    The logic of some things are intuitive to programmers – sort of like avionics :-)

    We’ll see if there are some other places where links could go.

  4. pranesh Says:

    Thanks Bruce. I’m a big fan of your column and for sometine, was struggling to find it. Pranesh

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