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What's More Dangerous: Light Or Strong Crosswinds?
When you think of landing accidents that happen in a crosswind, you usually think of windy days. Really windy days.
And it's true, a lot of landing accident do happen when the wind is gusting to 25 knots or more. But a surprising number of these accidents happen when the winds are light - even when the wind is less than 10 knots.
How is that possible? When you're dealing with a light crosswind, you only need a little correction to maintain centerline, right?
Here are three landing accidents from the NTSB's database where the crosswind component was less than 10 knots. We'll go through each of them, and then talk about what went wrong.
Accident #1: 2 Knot Crosswind On Rollout
According to the NTSB, the pilot reported that during the landing roll he encountered a crosswind, the left wing lifted, and the airplane began to drift left of the centerline. He attempted to correct with the right rudder and brake but the airplane departed the runway to the left. During the runway excursion, the airplane impacted an airport sign and came to rest on an adjacent runway.
The pilot stated that there were no mechanical malfunctions or failures with the airplane that would have precluded normal operation. Substantial damage was found to the right elevator and firewall. The reported wind at the airport about the time of the accident was from 080 degrees at 11 knots, which created a crosswind component of 2 knots for landing on runway 7.
Accident #2: 9 Knot Crosswind On Rollout
According to the NTSB, the pilot reported that during the landing roll it felt as if "air got under the wing." The airplane drifted to the left and departed the runway surface into the grass about 40 miles per hour. During the runway excursion, the pilot reported that he crossed over a parallel taxiway, the nose gear impacted a storm water ditch and collapsed. The firewall sustained substantial damage. According to the pilot, the reported wind from the airport automated surface observing system about the time of the accident was 350 degrees true at 9 knots, which resulted in a 9 knot crosswind component.
The pilot stated there were no mechanical malfunctions or failures with the airplane that would have precluded normal operation.
Accident #3: 9 Knot Crosswind On Landing
In the NTSB's report, the private pilot reported that, as the airplane approached the airport after the cross-country flight, he checked the weather, which indicated that the surface wind was from 230 degrees at 10 knots. He chose to land on runway 29 because runway 24 was closed. He stated that, on final approach, the "crosswind became evident."
After touchdown, the airplane veered sharply left. The pilot used steering and braking inputs to keep the airplane on the runway, but his efforts were not successful, and there was no noticeable reduction in speed. The airplane subsequently exited the runway surface and spun sharply left. The right main landing gear collapsed, and the right wing impacted the ground. The airplane sustained substantial damage to the fuselage, empennage, and right wing. Examination of the brakes, rudder, and nose wheel steering systems revealed no discrepancies.
How Can A Light Crosswind Cause So Many Problems?
As the famous saying goes, "the devil you know is better than the devil you don't." When you're dealing with a strong crosswind, you know it's there, and you're ready for it. But when the winds are light, they're harder to perceive and prepare for. And even in a light crosswind, if you're not prepared, things can quickly get out of control.
In all of these accidents, the pilot either wasn't prepared for the crosswind, or didn't perceive there to be a crosswind significant enough to affect their landing or rollout.
And in all three accidents, 2-9 knots of crosswind was all it took to send the aircraft careening off the runway.
Spring Is Prime Time For Crosswind Accidents
According to the NTSB, a larger number of crosswind accidents happen in the spring. There are a couple of factors at play here.
First, most pilots are "knocking off the rust" from a lack of flying in the winter. Anytime you're out-of-practice, you open yourself up to more risk.
And second, spring is typically the windiest season of the year. As the northern hemisphere heats up in spring, temperature differentials cause frontal systems to move more. And as the jet stream makes its way north for the summer, it brings with it lots of competing high and low pressure systems. When you have strong pressure systems (and pressure gradients), you get a lot of wind.
Getting Back In The Game, And Staying On The Runway
Even if you don't live in a windy place, a few knots of crosswind can throw you off. And if you're just getting back into flying, a little practice can go a long way.
First, make sure you know always know where the winds are coming from, so you can mentally prepare for a crosswind, no matter how light it is.
Almost any airport you fly into has either a broadcast weather or a windsock on the field, and usually both are available. Use them to make a mental picture of the crosswind you're dealing with.
Next up comes the stick-and-rudder part. Make sure you're ready to transition your plane from a crab on final, to the wing-low method all the way to touchdown.
If you haven't flown in a crosswind for awhile, grabbing an instructor and doing some practice patterns is a great way to get comfortable again this spring. Even a few trips around the pattern can help you see the difference between a crab, and having your nose pointing straight down the centerline with crosswind correction inputs. And that can be the difference between staying on the runway, and going off the side when your nose isn't aligned with the runway.
Finally, fly your airplane all the way through your rollout (and to the ramp, for that matter). That means keeping crosswind inputs in at all times. You never know when a gust of wind is going to try to weathervane your aircraft and try to send it off the edge of the pavement.
After all, staying on the runway is a lot better than an unexpected venture into the grass.
This is not an original article. It first appeared on boldmethod.com on 20 April 2017. To read the original article click here.
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