Watch Those Non-Water Water Landings

We make landings (hopefully) after every takeoff — it’s a reasonably simple process, once you learn how to do it right the first time, but there are some times when landings just don’t go the way we expect them to. In these cases, Mother Nature can turn out to be a real b—-, if you know what I mean.

STANDING WATER can spell real problems for airplanes, and more so for low wing airplanes. After significant downpours or melting snows, small to medium sized puddles can be left standing on the airport proper. In some cases, these puddles can even turn into small lakes and rivers, and that my friend, can spell problems for you and your airplane on landing.

THE SET UP — Our pilot is on his way back to his home field, after a nice weekend away. On board are the pilot’s wife, along with a friend and his wife, all of whom are tired and can’t wait to get back down to terra firma. What our pilot didn’t know is that a major storm had passed through hours before his arrival, and that storm had deposited several inches of rain on the airport property.

HEY, THAT’S NOT SUPPOSED TO BE THERE — As our pilot lined up his nice, low wing plane on the downwind leg, he noticed the shimmer of a little standing water on the runway. Not to worry he thought, it’s just a puddle, and is of no concern to my landing. Was our pilot in for a nasty surprise.

ON FINAL, he set up for a normal landing, with the landing gear down, flaps down full (it was a fairly short runway at 2400 feet), and power at minimum. Due to the short length of the runway, our pilot put it down on the numbers, and started to relax as the wheels touched down firmly and the plane began to slow.

…UNTIL HE CAME TO THE PUDDLE. Looking at the puddle from the air, it had looked fairly shallow. However, unbeknownst to our pilot, it was actually several inches deep. When the plane sliced into the puddle, there was a loud drumming noise on both sides of the plane, and the plane quickly decelerated. The passengers looked out the window, and gasped.

AS OUR PILOT LOOKED OUT, HE WAS AMAZED TO SEE THAT HIS PLANE’S FLAPS WERE NO LONGER FLAT. Each had a significant amount of curvature to it, centered directly behind each main landing gear wheel. After taxiing the plane back to the apron, the airport operator came out and had a look. Everyone was astounded — including the airport operator.

WHAT HAPPENED? Looking at the event, the airport operator and the pilot figured it out. As the wheel, traveling at around 100 miles per hour, sliced into the water, rooster tails of water shot out and directly impacted the extended flaps. Because the flaps on airplanes are designed to interact with air, the force of the huge amount of water on the flaps demolished them.

DON’T TURN YOUR PLANE INTO AN AMPHIBIAN. If you see significant water on the runway, either go to another airport or land short or long to avoid it. If you can’t avoid it, use heavy braking — prior to contact with the water — to help reduce the stresses on the airframe as you go through the water. If you can afford it, (i.e., the runway is really, really long) land without flaps. While this is no guarantee that the flaps won’t be damaged, having them up will reduce the likelihood of damage.

While this problem is more applicable to low-wing aircraft, high-wing planes can suffer damage too. Water presents much more resistance to landing gear than air or the rolling resistance of asphalt. As a result, the landing gear can be stressed by driving through mega-puddles at high speeds. This can damage the landing gear doors, the actuators that drive the gear … the list is long.

BOTTOM LINE: If you want to keep your plane from getting restyled by water, your best defense is to avoid water on the runway – PERIOD. By taking this approach, you will never have to explain to the airport operator or your insurance agent how you managed to put those neat new curves into your favorite airplane with a simple landing.