For those who quickly become confused about the forces acting for and against an airplane in flight, perhaps the following terms will help! Special thanks to http://www.aerospaceweb.org/question/design/q0101.shtml for the helpful diagram showing the axes!

ANGLE OF ATTACK The angle between the airfoil’s chord line and the direction in which the aircraft is currently moving. The amount of lift generated by a wing is directly related to the angle of attack.

CLEARANCE Formal instructions from air traffic control authorizing a specific route or action (climb or descend, entry into controlled airspace). Pilots may deviate from an ATC clearance in an emergency or when compliance would threaten safety of flight.

DECISION HEIGHT When flying an aircraft, the height at which a decision must be made during an instrument approach to either continue the approach or to execute a missed approach (abort).

DRAG Resisting force exerted on an aircraft in its line of flight opposite in direction to its motion. Opposite of thrust.

FLIGHT PLAN Filed by radio, telephone, computer, or in person with Flight Service Stations, a record of aircraft number; type and equipment, estimated time of departure and time en route, route and altitude to be flown, amount of fuel and number of persons aboard, home base and contact phone number; and other information.

LIFT Upward force generated by an aircraft wing as it moves through the air.

PATTERN The path of aircraft traffic around an airfield, at an established height and direction. At tower-controlled fields, air traffic controllers supervise the pattern by radio (or in non-radio or emergency conditions by red and green light signals.

PITCH (1) One of the three axes in flight, this specifies the vertical action, the up-and-down movement. (2) The angle of a propeller or rotor blade in relation to its arc; also the distance advanced by a blade in one full rotation.

ROLL One of three axes in flight, specifying the action around a central point.

ROTATE In flight, any aircraft will rotate about its center of gravity, a point which is the average location of the mass of the aircraft. The three-dimensional axes that determine the attitude or orientation of an aircraft are described as the yaw, pitch and roll.

SLIPSTREAM The flow of air driven backward by a propeller or downward by a rotor.

THRUST The driving force of a propeller or the forward force produced in reaction to the gases expelled rearward from a jet engine. Opposite of drag.

TRAFFIC PATTERN A standard rectangular flight pattern around the landing runway at an airport. Includes 45-degree or crosswind entry to the rectangle, with downwind, base and final legs as sides of the rectangle. Standard are 90-degree left turns around the rectangle (non-standard right-hand traffic pattern is noted in Airport Facility Directories) with downwind flown at a specified altitude, usually 1,000 or 1,500 feet above the airport elevation. At airports with a control tower; the pattern may be modified or short-cut according to ATC instructions.

VFR (Visual Flight Rules) A defined set of FAA regulations and “rules of the road” covering operation of aircraft primarily by visual reference to the horizon (for aircraft control) and see-and-avoid procedures (for traffic separation).

VORTICES Regions of high velocity that develop at the tip of a wing as it flies through the air.

WAKE TURBULENCE Turbulent air condition caused by small, tornado-like horizontal whirlwinds trailing an aircraft’s wingtips (wingtip vortices). Wake turbulence associated with larger aircraft flying at slow speeds (as on take-off or landing approach) is the most severe and can cause loss of control for smaller aircraft following close behind. Controllers use defined separation standards to avoid the problem for take-off, landing, approach and departure operations.

WEATHER MINIMUMS Lowest (worst) visibility conditions under which an aircraft may legally be flown under visual flight rules. When visibility is less than specified minimums, an aircraft must fly under instrument flight rules or not at all.

WIND SHEAR Large changes in either wind speed or direction at different altitudes that can cause sudden gain or loss of airspeed.

YAW One of the three axes in flight, specifying the side-to-side movement of an aircraft on its vertical axis.