Has NEXRAD Eliminated Thunderstorm Accidents?
This weekend's story about a trio of guys motoring around the Midwest in a Cessna 182 chasing tornadoes reminded me of what I don't see much of anymore: accidents involving penetration of thunderstorms. Twenty years ago, we used to see a couple of dozen of these every year. Now, I'd guess it's less than half that.
The reason should be obvious, even if I can't prove it. Datalink weather and ongoing improvements in weather displays in the cockpit have just about taken thunderstorms out of the accident equation. A 110-knot Cherokee can have a weather suite rivaling an Airbus, if not better.
Convective weather accidents often involved pilots flying places on instrument flight plans. They'd blunder into cells trying to run a line and rip the wings off the airplane or get hammered by hail, ice or turbulence. Stormscopes and Strike Finders helped; NEXRAD in the cockpit helped a lot more.
Flying into and around thunderstorms intentionally is nothing new and has been going on for years, although they never called it storm chasing. They called it weather research and the fact that it was done informs our knowledge of how thunderstorms and tornadoes form and move. These days, if YouTube and The Discovery Channel are to be believed, storm chasing has taken on a certain entertainment value. Not that I'm sniffing at that, mind you, for I'm way happier watching these guys run around the plains in camera-festooned SUVs than I am end-running a mesoscale line in an airplane.
I'm not sure what modern storm chasing is going to add to the knowledge base of avoiding cells in airplanes. As NEXRAD dissemination improves, the task is pretty simple: See the screen splotched with pulsating pepperonis? Don't fly there. If you've got onboard radar, too, so much the better, although it's good to understand attenuation. (In fact, I'm writing this from seat 25A in an airliner inbound to Wichita. It's skirting a dark area of cells off to the north.)
For those doing the chasing, thunderstorm hazards haven't changed much. And that applies to those of us who use NEXRAD or even just eyeballs to skirt a little too close. The late Dan Custis, who along with a few other pilots, flew a project to penetrate thunderstorms with an armored T-28, once told me that the experience led him to a surprising conclusion. And that was this: Except for one thing, if a pilot could keep the airplane upright in the clouds, a Cessna 172 could survive much of what might be encountered in a typical continental thunderstorm. What was the one thing? Hail. In this interview which appeared on AVweb in 2003, one of the T-28's pilot, Charlie Summers, said one problem the project consistently encountered was the engine pushrod tubes being hammered flat by hail impact. (The canopy itself had an armored outer cover.) Custis, by the way, wasn't suggesting anyone should penetrate cells in anything, but merely noting what his experience provided.
Hail can be just as deadly outside the cell, flying nearby in the bright sunshine, because hail shafts are often ejected from the top of the cell. Wayne Sand, an NCAR researcher at the time, once told me he was flying outside a cell with another pilot in a Twin Comanche. In the distance, they could see a large hailstone that seemed to be on a perfect trajectory to come through the windshield. It was and it did.
Back in my younger, dumber days, I skirted a cell too close and got into a vigorous column of grauple. If that stuff got another trip above the freezing level, it would have been grape-size hail and I might very well have been among those two dozen accident pilots common on those days. If being lucky is just as important as being good, I think I proved the point.