I have been studying general aviation accidents for almost 50 years and it is amazing that over all this period of time we have lost eight, plus or minus a few, IFR airplanes to thunderstorms each year. It's amazing because when I started there was little or no radar information on thunderstorms available, where now our cup runneth over with radar and lightning information. In 2004 there were eight airplanes lost in storms. They were high-value singles, light twins and a turboprop twin. All likely had some manner of weather-avoidance gear.
Apparently we need to step back and examine how all the available information is used, both in planning, the strategy part, and in flying, the tactics part. Tom Benenson, who is handling strategy, remarked when I told him to don his combat boots before writing that maybe we should call it "Shock and Awe." Maybe, because it is shocking that some pilots don't recognize thunderstorms for the awesome things that they are. But we'll stick with "Strategy and Tactics."
As we were discussing this, some mention was made that it might be addressed from the perspective of the new pilot and the experienced pilot. In truth, there is not much difference because thunderstorms don't discriminate. Scott Crossfield, with more experience than the rest of us could ever hope to have, lost a battle with a storm in north Georgia recently. And a perusal of the accidents shows a broad level of experience. Of the eight 2004 thunderstorm accidents reviewed, only three involved pilots with less than 1,000 hours. The high time pilot claimed 30,000 hours.
The simple fact is that once the airplane is in a thunderstorm, experience might not count for much. So, the trick is to stay out of the beasts. Does experience help here? Are there effective ways to do this? Read on.-RLC
Shock and Awe! Get caught in a thunderstorm and first comes the shock and then, if you're lucky and get out of it unscathed, comes the awe. There's no question that thunderstorms are the most frightening bogeymen lurking in the sky. With their booming bluster and spears of lightning, it's no wonder that primitive man thought they were a sign that the gods were angry. Even today, pilots who stray into a storm's murderous maw often call on their God for help.
In preparation for taking the private pilot knowledge exam we had to learn about thunderstorms. If we did our homework, we understood that all thunderstorms build around a cell with a distinct lifecycle that lasts about 30 minutes. During that 30-minute cycle, the storm goes through three phases. The first is the "towering cumulus stage," during which a cumulus cloud begins to grow vertically up to a height of some 20,000 feet.
As the storm grows it enters the "mature stage." A mature storm can reach heights of 40,000 to 60,000 feet and have both strong up- and downdrafts. This, the most dangerous stage of a thunderstorm, often produces large hail, damaging winds and flash floods.
When the downdraft cuts off the updraft, a storm enters its final phase, the "dissipating stage." With its supply of moist, warm air cut off, the storm can't sustain itself and weakens. The dissipating stage is often accompanied by light rain and weak winds flowing out from the storm.
Thunderstorms are a frequent occurrence, so chances are good that all of us who venture aloft are going to find ourselves sharing the sky with them at times. Meteorologists estimate that worldwide there are as many as 40,000 thunderstorms every day, some 14.6 million a year; in the United States alone there are something like 100,000 thunderstorms each year.
Since the prerequisites for the formation of thunderstorms are moisture, instability and a source of lifting, it shouldn't come as a surprise that the highest frequency of thunderstorms in the states is in the Southeast and that Florida has the most with some 80 to more than 100 thunderstorm days a year.
The seriousness of thunderstorms to flying safety is underlined in a study of 2004 NTSB final accident reports, the most recent available. In that year nearly 12 percent of all fatal general aviation accidents related to bad weather involved thunderstorms. Most of the accidents involved pilots flying on IFR clearances, but two pilots flying VFR came to grief because of convective activity.
Intellectually, we understand thunderstorms are to be avoided. We're taught to "see and avoid" to prevent midair collisions, but it's also a useful mantra to avoid tangling with one of Mother Nature's most violent manifestations. Risk assessment requires that if there are storms around-or forecasted-we have to be able to see them in order to avoid them. "Seeing" can mean looking out the windscreen or relying on lightning detection devices, on-board radar, or up- or down-linked weather. If we don't have a way to see the storms, the prudent decision is to wait and fly another time.
