it was looking for — nearly perpendicular winds at or exceeding speeds most airlines consider the limit for landing.

Keflavik is becoming the go-to location for crosswind testing, as Airbus tested the A380 in Iceland.

For most pilots, whether a student pilot or a veteran airline captain, making a good landing is matter of pride and something that is never guaranteed. Crosswind landings are typically among the most challenging.

Airport runways typically are normally aligned with the prevailing winds to make landings a bit easier, and many airports have runways aligned in different directions to account for changing wind. But the wind doesn’t always cooperate and at some point, every pilot has to make a landing with the wind blowing perpendicular to the runway.

Crosswind testing is important for the airplane makers because it allows them to confirm how strong a crosswind can blow while still allowing pilots to attempt a safe landing. All airplanes, big and small, have a limit to how much of a crosswind they can land in. This is usually dictated by how much the control surfaces (ailerons, rudder and elevator) can be used to keep the airplane flying along the runway heading despite being either crabbed or slipped into the wind.

In the 787 and other big airliners, pilots typically crab into the wind by using the rudder to point the nose of the airplane into the wind. When the airplane is very close to the ground, the pilot pushes on the other rudder pedal to align the nose with the runway while simultaneously using the ailerons to prevent the airplane from being blown down wind across the runway.

Unfortunately this can be a tricky balance of controls and without constant practice, the skill required to land in a crosswind can get rusty.

Most smaller airplanes have limits around 20-25 knots of wind coming straight across the runway. Large airliners may have limits of more than 30 knots.

The work performed by test pilots to find the limits of an airplane while landing in a crosswind are put to the test from time to time. In the video below, pilots of an Airbus A320 are attempting to land in Hamburg where winds were reported to be 35 knots, gusting to 47 roughly 60 degrees across the runway. The limit for a direct crosswind for the Airbus A320 is 33 knots, gusting 38.

While the co-pilot (who was flying during the landing) is de-crabbing close to the runway, left aileron input is applied and the left wing touches the runway, damaging the wing tip. The crew immediately elected to perform a go around. The airplane safely landed on a different runway more closely aligned with the wind about 20 minutes later. A full report on the landing can be found here (.pdf).

Authors: Jason Paur

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