VATUSA
Virtual Air Traffic Simulation - USA Division
Wake Turbulence
Wake Turbulence is defined as turbulence that is created by an aircraft that is passing through the atmosphere. The term also includes vortices, thrust stream turbulence, jet blast, jet wash, propeller wash, and rotor wash both on the ground and in the air. Generally, the heavier the aircraft the more wake turbulence that is generated. This occurs in all stages of flight, but is most prominent in the departure and approach phases of flight. Wake Turbulence is unpredictable by nature, and because of this, controllers are not responsible for anticipating its existence or effects. Although Wake Turbulence is not modeled by default in Flight Simulator, we as controllers are still responsible for providing appropriate separation due to Wake Turbulence.
Before we go into the regulations in regards to Wake Turbulence Separation, take a minute to watch the YouTube videos below. The first one is a video of a NASA Airliner Wing Vortice Test. This video will help illustrate the concept of Wake Turbulence. The second video is a pilot flying through the Wake Turbulence of another aircraft at Tuscon International. Notice how the pilot has to really fight the aircraft once he encounters the Wake Turbulence.
For the purposes of Wake Turbulence Separation aircraft are classified as Heavy, Large, or Small. For a detailed listing of aircraft weight classifications click here.
- Heavy aircraft are capable of takeoff weights of 255,000 pounds or more whether or not they are operating at this weight during a particular phase of flight. Some examples are most 707/C-135, all 747, 767, DC-10, L-1011, A-300, C-5, C-141, C-17, and B-52.
- Large aircraft are aircraft of more than 41,000 pounds but less than 255,000 pounds maximum takeoff weight. Most military, Air Carrier, and other non-General Aviation aircraft are Large.
- Small aircraft are aircraft of 41,000 pounds or less maximum takeoff weight. Most General Aviation aircraft are Small and most weigh 12,500 lbs or less.
Apply wake turbulence procedures to aircraft operating behind Heavy jets and, where indicated, to Small aircraft behind Large aircraft. Specific separations are listed in the appropriate sections. Separation shall continue to touchdown for all IFR aircraft not making a visual approach or maintaining visual separation.
Issue wake turbulence cautionary advisories, e.g. "CAUTION WAKE TURBULENCE" to:
- VFR aircraft behind a Heavy or B757.
- IFR aircraft that accept a visual approach or visual separation behind a Heavy or B757.
- Any aircraft if in your opinion wake turbulence may have an adverse effect on it.
