by Charles Gulick
Active runway: (Often shortened to simply “the active.”) The runway in use, based primarily on wind conditions and occasionally on traffic conditions. When more than one runway is in use, smaller aircraft are typically required to use the shortest runway.
AGL: Above Ground Level. Used to describe an aircraft's altitude above the ground. Aircraft instruments do not provide the pilot with this information. Altitude AGL must be deduced from a reading of the altimeter and charts or knowledge of the terrain over which the aircraft is operating.
Ailerons: Pilot-controllable surfaces on the rear or trailing edge of each wing, used to roll the aircraft and thus turn it. Acting in opposite directions, they increase lift on one wing while decreasing it on the other, causing the aircraft to roll on its longitudinal axis, then bank and turn in the direction of the lower wing.
Airfoil: A structural shape which creates or contributes to lift, such as the shape of an aircraft's wings and tail surfaces.
Airspeed indicator: A panel instrument notifying the pilot of the aircraft's rate of speed through the air. It operates by measuring the pressure of the relative wind against the wings. Indicated airspeed is not true airspeed nor is it the same as ground speed.
Altimeter: A panel instrument which tells the pilot the aircraft's altitude above sea level, also referred to as MSL (Mean Sea Level) altitude. The altimeter operates by measuring decreases or increases in atmospheric pressure, respectively, as the aircraft climbs or descends.
Angle of attack: The angle between the relative wind and the chord line of a wing or other airfoil. The chord line is an imaginary line through the center of an airfoil, drawn from the leading to the trailing edge.
Artificial horizon: A panel instrument depicting an aircraft's attitude with respect to the earth's horizon. It continuously updates and displays a symbol of the horizon, and of the aircraft's wings and nose in relation to that horizon.
ATC: Air Traffic Control. A ground-based radio network at many (but not all) airports, consisting of: Ground Control, which provides taxiing instructions; Tower, which provides instructions and clearances (permission) for takeoffs and landings; Departure Control and Approach Control, for the airspace immediately surrounding the airport; and Center, which controls the airspace at higher altitudes. Flight Simulator procedures cover only the Tower portion of the network, and that only to a minor degree.
ATIS: Automatic Terminal Information Service. A radio aid providing weather and other information about a given airport, including the designation of the active runway.
Atmospheric pressure: The pressure exerted on the earth by its atmosphere. Also termed “barometric pressure” because it is measured by a barometric device.
Auto-coordination: A system by which the ailerons and rudder of an aircraft are interconnected, so that control of one automatically provides coordinated control of the other, eliminating skidding or slipping in turns.
Bank: The lateral tilting of an aircraft—the result of rolling it about its longitudinal axis—which causes it to turn in the direction of the lower wing. The roll is begun by application of aileron in the desired direction of bank and turn.
Bleed off: To decrease a value, such as airspeed or altitude, in a slow and controlled manner.
Ceiling: The altitude at which the bottom boundary of the lowest cloud layer in an overcast will be encountered.
COM: Short for Communications. In Flight Simulator, the communications radio.
Control yoke: See Yoke.
Crabbing: A condition of flight in which, due to the direction of the winds aloft, the aircraft is moving somewhat sideways through the air, but following a straight line in relation to the ground. Named after the manner in which crabs move.
Density altitude: Pressure altitude (as shown on an altimeter) referenced to temperature, for computing aircraft performance.
Directional gyro: See Heading indicator.
DME: Distance Measuring Equipment, providing the pilot with a panel readout of the aircraft's distance from a VOR station, in nautical miles.
Drag: Forces that oppose an aircraft's movement through the air, acting parallel to, and in the same direction as, the relative wind.
Elevators: Pilot-controllable surfaces on the trailing edge of the horizontal stabilizer, used to pitch the aircraft's nose up or down, or keep it level with the horizon, thus controlling airspeed. The elevators are controlled by the yoke. Pulling back on the yoke moves the elevators up, and the relative wind forces the tail downward while the nose pitches up. Releasing back pressure or applying forward pressure on the yoke produces the opposite result.
FAA: Federal Aviation Administration.
Flaps: Pilot-controllable airfoils on the trailing edge of the wings, used to assist the pilot in takeoffs, slowflight, and landings. On takeoff, lowering or extending the flaps by 10 degrees (nominal) provides the highest lift-to-drag ratio, shortening the distance required to get airborne. Lowered flaps assist in slowflight by increasing drag and at the same time reducing the aircraft's stalling speed. On landing approaches, flaps are lowered—typically all the way—to accommodate a steeper angle of descent, for instance for clearing obstacles or flying tight airport patterns. Flaps also permit touchdown at a lower airspeed, because of a higher coefficient of lift and thus a lower stalling airspeed. After touchdown, the drag of the flaps shortens the landing roll.
Flare: The leveling-off phase of a landing approach, just prior to touchdown, bringing the aircraft level or slightly nose-high. It is performed a foot or so above the runway in actual aircraft, but somewhat higher than that in the simulator to compensate for the relative insensitivity and slow reaction-time of the simulated control.
FPM: Feet Per Minute. Used to measure an aircraft's rate of climb or descent.
Gear: See Landing gear.
Glideslope: A navigation aid used on ILS landing approaches, consisting of a horizontal needle which displays the correct vertical position for the aircraft in its approach to the runway threshold. The pilot works to keep the needle centered by continuously monitoring his angle of descent, and adjusting it as required. The glideslope is used in conjunction with the localizer.
Ground speed: An aircraft's actual speed over the ground, which is not available as an instrument readout but must be calculated.
Heading: The magnetic compass direction in which the aircraft is pointed, in relation to a 360-degree circle. It is not necessarily the direction the aircraft is traveling (see, for instance, Crabbing).
Heading indicator: (Also called the directional gyro.) A compass controlled by a gyroscope, which gives the pilot heading information based on forces which act on the gyro rather than on magnetic readings. It obviates the lag inherent in a magnetic compass, and requires no settling time, as does the latter, after turns and climbs.
Horizontal stabilizer: The fixed horizontal surface at the rear of the aircraft, equipped with controllable elevators.
IAS: Indicated Air Speed. Also see KIAS.
IFR: Instrument Flight Rules. The rules by which an aircraft must be flown when in instrument conditions, or when flight by visual reference (see VFR) is difficult or impossible.
ILS: Instrument Landing System. A system of radio aids that displays, on the pilot's instrument panel, three-dimensional references by which he can make an approach and landing without outside visual references. It consists of a localizer, glideslope, marker beacons, and approach lights (the latter not included in the Flight Simulators).
KIAS: Knots Indicated Air Speed. An aircraft's airspeed in knots per hour, as read on the airspeed indicator.
Knots: Nautical miles per hour, abbreviated kn. A knot is equal to 1.1507 statute miles, or conversely, a statute mile is equal to .869 knots. The simulator airspeed indicator and the DME read in knots.
Landing gear: The appendage of struts and wheels on which the airplane lands. Both the simulated Cessna and Piper aircraft have “tricycle” gear, comprised of a nose wheel and two main wheels, which enable the aircraft to sit level on the ground. Landings should, however, be made on the main wheels, with the nose wheel being lowered to the runway only after the plane has landed and slowed down.
Localizer: A radio navigational aid used in conjunction with the glide-slope on ILS landing approaches. The localizer needle is a vertical needle which displays the correct horizontal position for the aircraft on its approach to the runway threshold. The pilot works to keep the needle centered, by continuously monitoring his heading and adjusting it as required.
Magneto: A device that creates the high voltages required for aircraft engine spark plugs. It combines the functions of an automobile engine's coil and distributor.
Marker beacons: Labeled O, M, and I on the instrument panel, Outer, Middle, and Inner marker beacons consist of visible and audible signals which tell the pilot his relative distance from the end of the runway on ILS approaches.
NAV: Short for Navigation. In Flight Simulator, the navigation radios (NAV1 and NAV2).
OBI: Omni-Bearing Indicator. A panel instrument that gives the pilot information about the aircraft's position relative to the VOR station to which the NAV radio is tuned. It consists of an OBS or Omni-Bearing Selector for selecting a course or radial; a to-from indicator, advising whether the pilot is flying toward or away from the station; a CDI or Course Deviation Indicator (or “needle” for short) which the pilot works to keep centered; and in the case of NAV1, glideslope and localizer (glidepath) needles which indicate, respectively, the correct vertical and horizontal courses to the runway threshold on an ILS approach.
OMNI: Short for Omni-Bearing Indicator and/or its components, and also, loosely, a VOR station.
Phonetic alphabet: The terms used to transmit letters and numbers via aircraft radio, to prevent misundertandings:
Note that numbers are spoken as individual digits. For example, 297 is spoken “too niner seven.”
Pitch: The angle between the longitudinal axis of the aircraft and the horizon. Pitch is described as “nose up,” “nose down,” and “level.” We also say an aircraft is “pitched up” or “pitched down.”
Power setting: The amount of throttle, or fuel flow, applied to the engine, determined in the prototype by the position of the throttle (a push-pull control), and in the simulator by the number of notches applied to the throttle.
Rate of climb: The rate at which the airplane is climbing, measured in feet per minute. Also used, illogically, to define the rate at which the airplane is descending, though “rate of descent” is better applied to that condition. There can, however, be a zero rate of climb without confusion.
Rate of climb indicator: See VSI.
Rate of turn: The rate at which the aircraft is turning, measured in degrees per second, as a result of its airspeed and the sideways force, or horizontal lift component, which is causing it to turn. The rate of turn at any given airspeed is controlled by the angle of bank.
Rotation: The act of rotating the aircraft on takeoff, or using back pressure to raise the nose just prior to departing the ground. The aircraft is rotated as it reaches climb speed.
RPM: Revolutions Per Minute. The measure of the speed at which the aircraft's engine, and the propeller fastened to its crankshaft, are turning, as a result of the amount of throttle applied, the aircraft's pitch, and other flight conditions.
Rudder: Pilot-controllable surface on the trailing edge of the vertical stabilizer that controls yaw, or rotation about the aircraft's vertical axis.
Skid: A sliding of the aircraft to the left or right, out of alignment with the desired flight path. A skidding turn results when centrifugal force is greater than horizontal lift, pulling the aircraft toward the outside of the turn.
Slip: A yawing of the aircraft toward the outside of the path of a turn. A slipping turn results when horizontal lift is greater than centrifugal force.
Stack: (Also called “radio stack”) The section of the instrument panel where the COM, NAV and transponder are installed, usually in a stack on top of one another.
Tachometer: Often abbreviated “tach”. The instrument that measures the speed of rotation of the engine, in revolutions per minute (RPM).
TAS: True Air Speed. Airspeed after compensation for density altitude.
Taxi: To move an aircraft on the ground.
Throttle: The control that determines the speed of rotation of the engine's crankshaft, in revolutions per minute, by the rate at which it permits fuel to flow.
Trim: Small control surfaces affecting the elevators, making it unnecessary to maintain pressures on the yoke. In this book, trim is simulated by elevator settings, since no pressures can be felt in the simulator.
Vertical stabilizer: (Also called the “fin.”) A fixed vertical surface at the rear of the aircraft, to which a movable surface—the rudder—is hinged. The vertical stabilizer helps to stabilize the aircraft in the vertical or yaw axis.
VFR: Visual Flight Rules. Rules covering flights in visual conditions, or conditions when visual references are adequate for safe control of an aircraft. Compare IFR.
VOR Very high frequency Omnidirectional Range. A radio transmission system provided for pilots which enables them, with the necessary equipment, to navigate along or over magnetic course radials (all of which converge at specific VOR stations), and thus to navigate precisely throughout the airspace.
VOR station: The facility housing a VOR transmission system and equipment. Each VOR station has a name, usually that of an airport or nearby town.
VSI: Vertical Speed Indicator. A panel instrument showing the aircraft's rate of ascent or descent, in feet per minute.
Yaw: An aircraft's rotation about its vertical axis. The vertical axis is also called the yaw axis.
Yoke The pilot's control column, similar in appearance (but not performance) to an automobile steering wheel. The yoke incorporates aileron and elevator control, resulting from “pressures” applied by the pilot. The term “pressure” stresses the fact that the yoke is not pushed, pulled or turned abruptly or forcefully, but moved slowly and in small increments. Pressures to left or right operate the ailerons. Backward or forward pressures operate the elevators. The yoke returns to its neutral position when pressure is released.