Q

Q-band radar. Radar that operates in the frequency band from 36 to 46 gigahertz. At this frequency, the wavelength of the energy is between 0.834 and 0.652 centimeter.
QEC assembly (engine maintenance unit). An engine change assembly (quick engine change) that allows an aircraft engine to be changed with the least amount of downtime. The engine is mounted on the engine mounts, all of the accessories and the propeller are mounted on the engine, and the cowling is installed. The QEC assembly essentially contains everything forward of the firewall.
Q-factor of a coil. A measure of the quality factor of the coil. Q is the ratio of the inductive reactance of a coil to its resistance, both measured in ohms.

quadrant (aircraft controls). The housing in an aircraft cockpit on which the engine control levers are mounted. The top of the quadrant is in the shape of a quarter of a circle, and the control levers stick out radially from the quadrant.
quadrant (air traffic control). 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°, and NW quadrant 270° – 359°.
quadrant (mathematics). One of the four parts of a plane formed by the system of rectangular coordinates. The four quadrants are numbered with Roman numerals. I is the upper right-hand quadrant, II, the upper left-hand. III is the lower left-hand, and IV, the lower right-hand quadrant.
quadrantal error. The error in an automatic direction finder system installation caused by the metal in the aircraft. The quadrantal error is different in each of the four quadrants (front right, front left, rear left, rear right).