Certain propeller rpm settings or helicopter rotor speeds can cause the VOR course deviation indicator (CDI) to fluctuate as much as ±6°. Slight changes to the rpm setting will normally smooth out this roughness.

A device for propelling an aircraft that, when rotated, produces by its action on the air, a thrust approximately perpendicular to its plane of rotation. It includes the control components normally supplied by its manufacturer.

A series of mistakes that may lead to an accident or incident. Two basic principles generally associated with the creation of a poor judgment chain are: (1) one bad decision often leads to another; and (2) as a string of bad decisions grows, it reduces the number of subsequent alternatives for continued safe flight. ADM is intended to break the poor judgment chain before it can cause an accident or incident.

See Pilot’s Operating Handbook/Airplane Flight Manual.

Error in the indication of the altimeter, ASI, and VSI caused by the air at the static system entrance not being absolutely still.

A report over a known location as transmitted by an aircraft to ATC.

The initial tendency to return to a state of equilibrium when disturbed from that state.

Implies work rate or units of work per unit of time, and as such, it is a function of the speed at which the force is developed. The term “power required” is generally associated with reciprocating engines.

A complete engine and propeller combination with accessories.

The characteristic of a gyroscope that causes an applied force to be felt, not at the point of application, but 90° from that point in the direction of rotation.

Any or all forms of water particles (rain, sleet, hail, or snow) that fall from the atmosphere and reach the surface.

A form of radio interference caused by rain, snow, or dust particles hitting the antenna and inducing a small radio-frequency voltage into it.

A system of lights similar to the VASI, but consisting of one row of lights in two- or four-light systems. A pilot on the correct glideslope will see two white lights and two red lights. See VASI.

Ignition occurring in the cylinder before the time of normal ignition. Preignition is often caused by a local hot spot in the combustion chamber igniting the fuel-air mixture.

Altitude above the standard 29.92 “Hg plane.

A demand oxygen system that supplies 100 percent oxygen at sufficient pressure above the altitude where normal breathing is adequate. Also referred to as a pressure breathing system.

The greatest horizontal visibility equaled or exceeded throughout at least half the horizon circle (which is not necessarily continuous).

Simple or minor preservative operations and the replacement of small standard parts not involving complex assembly operation as listed in 14 CFR part 43, appendix A. Certificated pilots may perform preventive maintenance on any aircraft that is owned or operated by them provided that the aircraft is not used in air carrier service.

A display that provides increased situational awareness to the pilot by replacing the traditional six instruments used for instrument flight with an easy-to-scan display that provides the horizon, airspeed, altitude, vertical speed, trend, trim, and rate of turn among other key relevant indications.

Designated airspace within which flight of aircraft is prohibited.

Operation by the use of compressed air.

The shape or form of a wing as viewed from above. It may be long and tapered, short and rectangular, or various other shapes.

See precision approach path indicator.

See precipitation static.

Lines of latitude.

Drag caused by the friction of air moving over the aircraft structure; its amount varies directly with the airspeed.

The weight of occupants, cargo, and baggage.

The embodiment of personal traits and characteristics of an individual that are set at a very early age and extremely resistant to change.

A tendency for an aircraft to yaw to the left due to the descending propeller blade on the right producing more thrust than the ascending blade on the left. This occurs when the aircraft’s longitudinal axis is in a climbing attitude in relation to the relative wind. The P-factor would be to the right if the aircraft had a counterclockwise rotating propeller.

See primary flight display.

Long-period oscillations of an aircraft around its lateral axis. It is a slow change in pitch accompanied by equally slow changes in airspeed. Angle of attack remains constant, and the pilot often corrects for phugoid oscillations without even being aware of them.

See pilot in command.

Navigation by visual reference to landmarks.

The pilot responsible for the operation and safety of an aircraft.

Report of meteorological phenomena encountered by aircraft.

FAA-approved documents published by the airframe manufacturer that list the operating conditions for a particular model of aircraft.

See pilot report.

Ram air pressure used to measure airspeed.

A combination pickup used to sample pitot pressure and static air pressure.