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Chapter 15 | Operational Information
(998 millibars). That error represents an indicatedaltitude difference of some 485 feet! Probably the most noticeable difference between international flight operations and domestic flight operations is radio communication, with phraseology and procedures varying in many respects. In most parts of the world outside the United States, strict adherence to proper terminology is required (“diagonal” versus “slash,” “decimal” versus “point,” “zero” versus “oh”, etc.); however, other areas of the globe operate in a mix of aviation English, local language, and local slang. American slang is generally not understood and local phraseology may not be familiar to many U.S. pilots, so be careful! International operations should be studied every time you fly out of your home country, not just at recurrent training sessions.
Wake Turbulence When stepping up to turbine-powered aircraft, you will often be operating at airports with high traffic densities and where the majority of traffic is composed of large aircraft. Most high-density airports have closely spaced parallel or intersecting runways, with approach and departure aircraft strung out 15–75 miles in several directions.
Operating under these conditions you’ll constantly be confronted with situations where understanding of wake turbulence is required. You must know its causes, effects, and how to avoid it in order to give your passengers a smooth and safe ride. This section reviews some common procedures for avoiding wake turbulence hazards.
Wing Tip Vortices As you know, an aircraft wing creates lift by developing a pressure differential: low pressure over the wing’s upper surface and higher pressure underneath the wing. For most of the wingspan, this pressure differential translates directly into lift. However, something a bit different happens out at the wing tip. As lift is created, some of the high-pressure air from under the wing rolls up around the wing tip toward the lower-pressure area on top. The result is sort of a mini “horizontal tornado” called a wing tip vortex. These wing tip vortices trail from the aircraft’s wing tips and are the source of the hazard known as “wake turbulence.” Since vortices are byproducts of lift, they are created from the time an aircraft begins to fly until it touches down on landing (Figure 15.8).
aircraft flight path
Wing tip vortices trail behind and below aircraft flight path and diverge slowly to the sides.
FIGURE 15.8 | Wing tip vortices.
