There are a lot of performance metrics in aviation, and one of them is crosswind component. In short, it’s the speed of the wind that, when exceeded, means to run out of rudder authority.
In training airplanes such as the Cessna 172, you will find a notation of the “demonstrated crosswind” with the caveat “not a limitation.” To get this information the aircraft manufacturers put their airplanes into crosswind conditions to see that it can handle them.
Boeing has taken this to the next level with the testing of its 777X. The aerospace giant has released video of the test aircraft attempting to land in winds of 40-60 knots in Lubbock, Texas.
According to Boeing test pilot Heather Ross, the process involves a combination of testing the aircraft design in high winds using a flight simulator to see what it is capable of, and then looking for high winds in the real world to verify the procedures established in the simulator so that the pilots who will ultimately fly the aircraft know what to expect and what procedures are best practices.
The video shows the airplane crabbed into the wind, then during the transition from approach to landing the nose is aligned with the centerline of the runway.
“We are looking to establish the maximum amount of crosswind that we can and we can demonstrate,” said Ross. “Those are used by our customers, the airlines.”
A Long Process
Determining the crosswind component for an aircraft is a team effort. According to Ross, Boeing meteorologists spend weeks and months looking for potential strong crosswinds at a runway environment that can accept the 777X. When they are found, the crew launches for real-world testing.
Flight students are taught to use a combination of rudder and aileron to line up an airplane on the centerline during landing. This is often done using a combination of rudder and “low wing into the wind.”
If the pilot runs out of rudder, and the aircraft is no longer aligned with the runway, the best course of action is a go-around. In a piston-powered aircraft, full throttle usually means the power comes up immediately. In a turbine-powered aircraft, the power has to spool up, so there’s a bit more of a lag time that requires pilots to know precisely what the performance parameters are for their airplane.
