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Blowin' in the windBlowin' in the wind

Here in central Maryland supporting evidence has been elusive, but spring has at least theoretically begun to arrive in the warmer parts of the country. (We’ll believe it when we see it.) AOPA’s home base has also seen nearly relentless winds for the past six weeks or so—not quite up to West Texas standards, but still gusts of around 25 knots almost every afternoon. This has gotten us thinking about an odd pattern first noted in the February 12 issue of Flight School Business: While general aviation accidents overall are most frequent in the summer, landing accidents tend to peak in the spring. At the time, we guessed that one factor might have been that too many pilots don’t bother getting a little dual after a winter layoff. On the other hand, maybe the spring’s just windier.

Digging into the data helps untangle some of this. First off, the springtime bump in landing accidents certainly seems to be real. Looking over 10 years’ worth of fixed-wing accidents (2002 to 2011), we find that the total number increased by 54 percent from winter to spring, while the number of landing accidents jumped 83 percent. Additional landing prangs made up almost half the overall increase. Summer saw 37 percent more accidents than spring, but only 16 percent more bungled landings. Going into the fall, both dropped by just about one-third, with a further drop of about 30 percent from fall into winter. Landings were 28 percent of all accidents in the other three seasons but more than 33 percent in the spring.

So there’s not much doubt that spring sees a rash of bad landings. The details also vary with the season. Losses of directional control are always the most common variety, but they peak in the spring, too. They accounted for 43 to 45 percent of landing accidents in the other three quarters, but 52 percent in the spring, and a larger share of a larger number equals, well, more. From winter to spring, when the total number of landing accidents increased 83 percent, the number ascribed to loss of directional control climbed 120 percent. From spring to summer, though, the number of losses of directional control barely increased another 1 percent.

All of which gives credence to the notion that pilots have a harder time keeping rubber aligned with pavement during the months of March, April, and May (which is how we defined “spring” for the purposes of this analysis). But which pilots? Contrary to what one might have expected, it turns out not to be students. The share of loss of directional control accidents that happens on student solos actually peaks in the winter, perhaps due to more exposure to slippery or contaminated runways (the share of accidents due to runway conditions is also highest in the winter). Solo students accounted for 12 to 13 percent of loss of directional control accidents in spring, summer, and fall alike.

Student pilots’ relative immunity to the spring malaise is less surprising when you bear in mind that both flight schools and independent instructors usually place sharp limits on weather conditions for student solos, particularly crosswind components. Of course, the weather doesn’t always follow the script, and once airborne, a student’s going to have to land somewhere no matter how gusty the breeze has gotten. But banning solos when the net crosswind is expected to be more than, say, 5 knots goes a long way toward reducing exposure to this particular hazard. No doubt it also helps that students invariably get a lot of dual just before receiving their solo endorsements, and in particular have put in a lot of time concentrating on their landings. The whole question of whether it’s wise to take to the skies without adult supervision after having flown, say, two hours during the preceding four months generally doesn’t come up.

That’s not the case for certificated pilots, who are pretty much left on their own in deciding whether they’re ready to try their luck in that first 10-knot crosswind of the season. The risk-reward calculus would seem to favor taking some dual first, if only because the risks are negligible: About half of all losses of directional control involved private pilots, but those taking dual lessons account for only 2 to 3 percent of all landing losses of directional control in each season. Those flying single-pilot suffered 42 percent of all winter losses of directional control and 47 to 49 percent in the warmer seasons. This gives us another measure of the spring effect: In the winter, private pilots had 15 single-pilot losses of directional control for every one on a dual lesson. In the spring that ratio jumped to 24 before dropping back to 14 over the summer.

So is the underlying problem rust, or gusts? Sadly, the data don’t make it easy to tell, but then, it may not make much difference. The obvious remedy is the same either way: Spring is the perfect time for established pilots to seek a little refresher training, preferably with some attention to crosswind landings.

ASI Staff

David Jack Kenny

David Jack Kenny is a freelance aviation writer.

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