Wing strut attached to the fuselage.

The indicated airspeed of an aircraft, corrected for position and instrument error. CAS is equal to true airspeed in standard atmosphere at sea level. Compare INDICATED AIRSPEED and TRUE AIRSPEED.

The convex or concave curvature of an airfoil.

An arrangement in which the horizontal stabilizer and elevators of an aircraft are mounted in front of the main wing(s).

Clear-Air Turbulence.

Ceiling and Visibility Unlimited; ideal flying weather.

1) The heights above the earth's surface of the lowest layer of clouds or obscuring phenomena that is reported as "broken," "overcast," or "obscuration," and not classified as "thin" or "partial". (2) The maximum height above sea level in Standard Air attainable by an aircraft under given conditions — SEE ABSOLUTE CEILING, SERVICE CEILING.

An Air Route Traffic Control Center (ARTCC).

The longitudinal and lateral point in an aircraft where it is stable; the static balance point.

An airport operating under FAR Part 139. The FAA issues airport operating certificates to all airports serving scheduled or unscheduled air carrier aircraft designed for more than 30 passenger seats. Certificated airports must meet minimum safety standards in accordance with FAR Part 139.

The measurable distance between the leading and trailing edges of a wingform.

Airspace not designated as Class A, B, C, D or E.

A cockpit control that changes the pitch of a helicopter's rotor blades; used in climbing or descending.

A circular duct on a radial engine into which exhaust gases from its cylinders are discharged.

A frequency designed for the purpose of carrying out airport advisory practices while operating to or from an airport without an operating control tower. The CTAF may be a UNICOM, Multicom, FSS, or tower frequency and is identified in appropriate aeronautical publications.

An air carrier operator operating under 14 CFR 135 that carries passengers on at least five round trips per week on at least one route between two or more points according to its published flight schedules that specify the times, day of the week, and places between which these flights are performed. The aircraft that a commuter operates has 30 or fewer passenger seats and a payload capability of 7,500# or less.

A bearing as indicated by the horizontal angle between the compass needle and the centerline of the aircraft. A Compass Course is equal to a True Course ± variation and deviation; also equal to a Magnetic Course ± deviation.

The North point at which a liquid compass needle points, rather than Geographical, or True, North. Compare MAGNETIC NORTH.

SEE RADIO NAVIGATION

A hydraulically-controlled propeller that governs an engine at its optimum speed by the blade pitch being increased or decreased automatically.

Streaks of condensed water vapor created in the air by aircraft flying at high altitudes; aka Vapor Trails.

An airspace of defined dimensions within which air traffic control service is provided to IFR flights and to VFR flights in accordance with the airspace classification. Controlled airspace is a generic term that covers Class A, B, C, D, and E airspace. Controlled airspace is also that airspace within which all aircraft operators are subject to certain pilot qualifications, operating rules, and equipment requirements in FAR Part 91. For IFR operations in any class of controlled airspace, a pilot must file an IFR flight plan and receive an appropriate ATC clearance. Each B, C, and D airspace area designated for an airport contains at least one primary airport around which the airspace is designated (for specific designations and descriptions of the airspace classes, refer to FAR Part 71. Class A (formerly PCA - Positive Control Area) generally, that airspace from 18,000' mean sea level (MSL) up to and including flight level (FL) 600 (60,000' pressure altitude), including the airspace overlying the waters within 12 nautical miles of the coast of the 48 contiguous States and Alaska. Unless otherwise authorized, all persons must operate their aircraft under IFR. Class B (formerly TCA - Terminal Control Area) Generally, that airspace from the surface to 10,000' MSL surrounding the nation's busiest airports in terms of airport operations or passenger enplanements. The configuration of each Class B airspace area is individually tailored and consists of a surface area and two or more layers (some Class B airspace areas resemble upside-down wedding cakes), and is designed to contain all published instrument procedures once an aircraft enters the airspace. An ATC clearance is required for all aircraft to operate in the area, and all aircraft that are so cleared receive separation services within the airspace. The cloud clearance requirement for VFR operations is "clear of clouds." Class C (formerly ARSA - Airport Radar Service Area) Generally, that airspace from the surface to 4,000' MSL above the airport elevation surrounding those airports that have an operational control tower, are serviced by a radar approach control, and that have a certain number of IFR operations or passenger enplanements. Although the configuration of each Class C area is individually tailored, the airspace usually consists of a surface area with a 5 nautical mile (nm) radius, an outer circle with a 10 nm radius that extends from 1,200' to 4,000' above the airport elevation and an outer area. Each person must establish two-way radio communications with the ATC facility providing air traffic services prior to entering the airspace and thereafter maintain those communications while within the airspace. VFR aircraft are only separated from IFR aircraft within the airspace. Class D (formerly ATA - Airport Traffic Area and CZ - Control Zone) Generally, that airspace from the surface to 2,500' MSL above the airport elevation surrounding those airports that have an operational control tower. The configuration of each Class D airspace area is individually tailored and when instrument procedures are published, the airspace will normally be designed to contain the procedures. Arrival extensions for instrument approach procedures may be Class D or E airspace. Unless otherwise authorized, each person must establish two-way radio communications with the ATC facility providing air traffic services prior to entering the airspace and thereafter maintain those communications while in the airspace. No separation services are provided to VFR aircraft. Class E (formerly General Controlled Airspace) Generally, if the airspace is not Class A, B, C, or D, and is controlled airspace, it is Class E airspace. Class E airspace extends upward from either the surface or a designated altitude to the overlying or adjacent controlled airspace. When designated as a surface area, the airspace will be configured to contain all instrument procedures. Also in this class are Federal airways, airspace beginning at either 700' or 1,200' AGL used to transition to/from the terminal or enroute environment, enroute domestic, and offshore airspace areas designated below 18,000' MSL. Unless designated at a lower altitude, Class E airspace begins at 14,500' MSL over the USA, including that airspace overlying the waters within 12 nautical miles of the coast of the 48 contiguous States and Alaska, up to, but not including 18,000' MSL, and the airspace above Flight Level 600.

Having two main landing wheels at the front and a tailwheel or tailskid at the rear as opposed to having a tricycle gear with three main wheels. Such an aircraft is popularly called a TAILDRAGGER.

A controllable louvre to regulating airflow through an engine's cowling.

A circular, removable fairing around an aircraft engine (generally radial) for the purposes of streamling or cooling; aka RING COWLING.

A rudder-controlled yawing motion to compensate for a crosswind in maintaining a desired flight path, as in a landing approach.

SEE COMMON TRAFFIC ADVISORY FREQUENCY