Q factor of a coil The performance measurement of an inductance coil. It is the ratio of the inductive reactance to the resistance of a coil.

Q-band radar Radar operating in a frequency range of 36 to 46 gigaherz (wave length of approximately 7 millimeters). Used primarily in Very Large Array (VLA) intergalactic research.

QEC unit A completed assembly of a basic engine and the necessary components for a particular airframe installation. A quick engine change (QEC) unit consists of an engine with all of the accessories and propeller already installed. Minimizes the time it takes to replace an engine. Also referred to as a quick engine change assembly (QECA) or a QEC kit.

QFE Height above airport elevation (or runway threshold elevation) based on local station pressure.

QNE Altimeter setting 29.92 inches of mercury, 1013.2 hectopascals or 1013.2 millibars.

QNH The barometric pressure as reported by a particular station.

Q-springs A system that provides artificially produced feedback of the control surface movement to the pilot. Necessary because large, high-speed aircraft normally utilize hydraulically actuated controls that provide no natural feedback to the pilot.

quad-clamp A quick-attach-detach clamp used to attach accessories to their gearbox mounting pads.

quadrant 1. The location of an aircraft s pivoting engine control levers. Some aircraft use push-pull knobs in the instrument panel. 2. A quarter part of a circle, centered on a NAVAID, oriented clockwise from magnetic north as follows: NE quadrant 000-089, SE quadrant 090-179, SW quadrant 180-269, NW quadrant 270-359. 3. In mathematics, one of four equal segments defined by the intersection of the two main axes of the rectangular coordinate system.

quadrantal error In navigation, the angular error in a measured bearing due to the presence of metal structures and engines in the vicinity of the direction-finding antenna.

quality control (QC) A management and inspection function that controls quality, standards, and performance in the manufacturing and repair of aircraft, aircraft engines, and components.

quantity An amount or portion. The total amount of a particular thing.

quantum A quantity or amount.

quantum theory A branch of physical theory involving the transference or transformation of energy in an atomic or molecular scale based on the concept of the subdivision of radiant energy into finite quanta.

quart A liquid measurement of volume equal to 1/4 gallon, 2 pints, or 57.75 cubic inches.

quarter-sawed wood Lumber cut at 45 across the annual rings.

quarter-turn cowl fastener A quick-release cowling fastener that requires only 1/4 turn to either fasten or release. Examples: Dzus or Camloc fasteners.

quarter-wave antenna The length of a radio antenna that is one quarter of the wavelength of the frequency for which the antenna is used.

quartz A mineral found in nature in the form of a six-sided crystal.

quartz crystal A thin slice of quartz used in electronic devices to control frequency. A quartz crystal vibrates when an electrical pulse is applied. The frequency is dependent on the size, shape, and thickness of the crystal.

quartz glass Glass constructed of pure quartz.

quartz lamp A lamp constructed with quartz glass. Quartz glass does not absorb ultraviolet rays as regular glass does.

quartz oscillator An electronic frequency generator that uses a quartz crystal to control frequency.

quartz-iodine lamp Lamps with a tungsten filament in a nitrogen-argon gaseous medium to which bromine has been added, enclosed in an envelope of quartz. These lamps have an operating life two to three times that of standard incandescent lamps and do not blacken with age. Now referred to as tungsten-halogen quartz lamps.

quasi-stationary front A stationary or nearly stationary front. Conventionally, a front that is moving at a speed of less than 5 knots is generally considered to be quasi-stationary. Commonly referred to as a stationary front.

quench hardening A ferrous alloy hardened by austenitizing and then cooling rapidly enough so that some or all of the austenite transforms to martensite.

quenching The rapid cooling of a metal as part of the heat-treating process. The metal is removed from the furnace and submerged in a liquid such as water, oil, or brine.

queuing The placement, integration, and segregation of departure aircraft in designated movement areas of an airport by departure fix, EDCT, and/or restriction.

quota flow control A flow control procedure by which the Central Flow Control Function (CFCF) restricts traffic to the ARTC Center area having an impacted airport, thereby avoiding sector/area saturation.

quotient The number resulting from the division of one number by another.