-by Niladri Roy
An important skill we are taught as student pilots is cross-wind taxiing.
An important skill we are taught as student pilots is cross-wind taxiing.
The purpose of cross-wind taxi technique is to prevent the wind from getting under one of the wings (especially in high-wing airplanes) and flipping the plane over sideways, and/or preventing the wind from getting under the elevator and tipping the airplane on its nose.
The Theory
If the wind is a direct headwind, tailwind, or sideways wind blowing directly at either wingtip, the POH recommends no explicit elevator or aileron correction, and the elevator and ailerons may be held neutral. (I have experienced violent disagreement on this point, especially from tail-dragger pilots. Their recommendation in case of a perpendicular side wind is to hold the ailerons completely left or right so that the yoke is pointing into the wind. This makes perfect sense once one visualizes the nose up attitude of the tail-dragger while on the ground, and the propensity for tail-dragger wings, therfeore, to catch much more wind than, say, a high-wing plane like the Cessna 172, whose wings are pretty much horizontal and level during taxi. Many tail-draggers are also made of particularly light material, eschewing aluminum in favor of fabric or Lexaan. This essentially makes them very large 'kites' that must be 'flown' as much on the ground as in the air).
In a left quartering headwind the correct taxi technique is to move the aileron of the left wing up so that the wind can blow on it and keep the left wing pushed down. Similarly, a right quartering headwind requires the right aileron to be up. In either case, the elevator is held neutral.
In a left quartering tailwind, the correct taxi technique is to hold the left aileron down, so that the wind can blow on it from behind and keep the left wing pushed down. Similarly, a right quartering tailwind requires the right aileron to be down. In addition, the elevator is held down in either case, so that the wind can keep the tail pushed down, and not try to tip the aircraft over on its nose. In tail-draggers, this has the added benefit of keeping the tail-wheel planted firmly on the ground.
Typically the POH contains a diagram that depicts the proper deployment of ailerons and elevator during taxi, as shown below:
Remembering Cross-Wind Taxi Technique
Even after understanding the theory, however, the diagram can be quite intimidating to remember for the new student pilot. Given below is a technique to simplify that task. Assuming you are aware that both the elevator and the ailerons are held neutral in direct head, tail or side winds, there are only two things you need to remember:
1. For any quartering wind from the front (no matter left or right): elevator neutral. Any quartering wind from the back (no matter left or right): elevator down
2. If the wind direction makes a left slanting diagonal, like a back-slash, through the center of the plane (when viewed from top), then turn the yoke left (i.e. in the direction of the diagonal); if the wind direction makes a right slanting diagonal, like a forward-slash, through the center of the plane, turn the yoke right (i.e. in the direction of the diagonal). A look at the figure below will make this very clear:
A Nifty Trick
Your checklist probably tells you to align your heading indicator with the magnetic compass during runup. But a nifty trick you can use is to align the heading indicator (directional gyro) to the compass before you start taxi, so that (as long as you remember which direction the ATIS said the wind was from) you will always be able to tell along which diagonal the wind is blowing in relation to your position simply by checking what kind of 'diagonal' that direction makes with respect to your current heading. Be sure to realign the heading indicator again with the magnetic compass once you are at runup in order to correct for any gyro precession during taxi.
"Turn into a headwind; dive away from a tailwind"
