Aviation Glossary

Aviation Glossary

Adverse Yaw - Yaw generated when the ailerons are used. The lifting wing generates more drag, causing an airplane to yaw (or turn) toward it.

AGL - (Above Ground Level) Altitude expressed as feet above the ground or terrain. It is usually set to indicate the airport field elevation during the pre-takeoff checklist.

Airspeed Indicator - An instrument or device that measures the airspeed of an aircraft through an air mass but not its groundspeed.

Altimeter - An adjustable cockpit instrument used to measure an aircraft’s altitude.

Altimeter Setting - A reference setting on the altimeter so that the instrument indicates an accurate altitude.

Center of Gravity (CG) - The longitudinal and lateral point in an aircraft where it is stable; the static balance point.

Class A Airspace - Airspace between 18,000 and 60,000 feet MSL (Mean Seal Level) over the contiguous United States. IFR clearances are required for all aircraft operating in Class A airspace.

Class B Airspace - Airspace area around the busiest U.S. hub airports (i.e. Chicago O’Hare), typically to a radius of 20 nautical miles and up to 10,000 feet AGL (Above Ground Level). Operations within Class B airspace require an ATC clearance (Air Traffic Control) and at least a Private Pilot certificate (local waivers are available), radio communications, and an altitude-reporting transponder (Mode C).

Class C Airspace - Airspace area around busy U.S. airports (other than Class B). Radio contact with approach control is mandatory for all traffic. Typically it includes an area from the surface to 1,200 feet AGL out to 5 miles and from 1,200 to 4,000 feet AGL to 10 miles from the airport.

Class D Airspace - Airspace around an airport with an operating control tower; typically to a radius of 5 miles and from the surface to 2,500 feet AGL. Radio contact with the control tower is required prior to entry.

Class E Airspace - General controlled airspace comprising control areas, transition areas, Victor airways, the Continental Control Area, etc.

Class G Airspace - Uncontrolled airspace, generally the airspace from the surface up to 700 feet or 1,200 feet AGL in most of the U.S., but up to as high as 14,500 feet in some remote Western mountainous and sparsely populated areas.

Controlled Airspace - A generic term including all airspace classes in which ATC services are available. VFR aircraft may operate without ATC contact in most controlled airspace as long as weather conditions will permit them to see and avoid other aircraft.

Conventional Gear – Having two main landing wheels at the front and a tail wheel at the rear (as opposed to a “tricycle gear” with two mains and front or nose wheel.) Conventional gear aircraft are popularly called ”taildraggers”. A Piper J-3 Cub is an example of this.

Common Traffic Advisory Frequency (CTAF) - A communications radio 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, flight service station, or tower frequency and is identified in appropriate aeronautical publications and on all visual flight rules (VFR) sectional maps.

Empennage - An aircraft’s tail group including the rudder, vertical fin, stabilizers and elevators.

FAR PART 61 - The section or part of the Federal Aviation Regulations (FARs) covering pilot certification and standard flight school operations. FAR PART 61, Sub Part J, outlines in detail all requirements that need to be met by a sport pilot candidate.

FAR PART 91 - The section or part of the Federal Aviation Regulations (FARs) covering the flight rules and regulations pertaining to non-commercial flight operations. FAR PART 91 provides you with the “rules of the sky” that you must comply with to operate as a safe non-commercial pilot.

FBO (Fixed Base Operator) - An airport-based business that parks, services, fuels, and may repair aircraft; often rents aircraft and provides flight training. The term was coined to differentiate FBOs from businesses or individuals without an established place of business on the airport.

Flap - A movable, usually hinged airfoil set in the trailing edge of an aircraft wing, designed to increase lift or drag by changing the camber of the wing or used to slow an aircraft during landing by increasing lift.

Flight Envelope - An aircraft’s performance limits, specifically the curves of speed plotted against other variables to indicate the limits of speed, altitude, and acceleration that a particular aircraft cannot safely exceed.

General Aviation - The 92 percent of U.S. aircraft and more than 65 percent of U.S. flight hours flown by other than major and regional airlines or the military. Often misunderstood as only small, propeller-driven aircraft. Even a large jet or cargo plane operated under certain federal rules can be a general aviation aircraft.

Gross Weight - The total weight of an aircraft when fully loaded, sometimes referred to as takeoff weight. The aircraft manufacturer, through testing and certification, determines gross weight for the aircraft.

Ground Speed – The actual speed that an aircraft travels over the ground (its “shadow speed”); it combines the aircraft’s airspeed and the wind velocity relative to the aircraft’s direction of flight.

Knot - (Nautical mile per hour) The most common measure of aircraft speed. 100 knots is equal to 115 miles per hour. (For miles per hour, multiply knots by 1.15.)

Nautical Mile - The most common distance measurement in aviation. A nautical mile is equivalent to 1.15 statute (standard U.S.) miles.

N-Numbers - Federal government aircraft registration numbers. U.S. registered aircraft numbers begin with “N” (example: N23299F).

Nontowered Airport - An airport without a control tower - the majority of America’s 13,000 airports. Only 680 airports have control towers. Nontowered airports are far from being uncontrolled. Pilots follow traffic pattern procedures and self-announce positions and intentions using the common traffic advisory frequency (CTAF), usually called the UNICOM frequency.

Prohibited Area - Airspace designated under FAR Part 73 within which no person may operate an aircraft without the permission of the using agency. It is most always distinctly marked on the VFR sectional maps.

See-and-Avoid - The FAA requirement that all pilots are ultimately responsible for separation from other aircraft when visual conditions permit spotting traffic.

Solo - After typically 12-20 hours of initial flight training, qualified student pilots are permitted to undertake some flights to build experience and confidence without a flight instructor on board. A first solo requires a written endorsement by the student’s flight instructor (and a third-class medical certificate) if training for the private pilot certificate. The first solo is a major event for any pilot and traditionally includes three takeoffs and landings at the student’s home airport.

Stall - An aerodynamic condition that has nothing to do with engine operation. It occurs when lift-producing airflow over the wings is disrupted or lost because the angle of the wings to the airflow (angle of attack) is too high. Student pilots are trained in stall prevention, recognition and recovery.

Student Pilot - A pilot who is training for a sport pilot or private pilot certificate, either before or after the first solo. A sport pilot student pilot must obtain a student pilot certificate through the FAA or a designated source, such as the National Association of Flight Instructors headquarters, while a private pilot student must obtain a third-class medial certificate through a medical examination by an FAA-designated aviation medical examiner before being allowed to fly solo in a powered aircraft. The student pilot certificate, once signed by the flight instructor, becomes the official student pilot certificate and must be carried with the student on every solo flight made.

Torque - A twisting, gyroscopic force acting in opposition to an axis of rotation, such as with a turning propeller.

Touch-And-Go - Landing practice wherein an aircraft does not make a full stop after a landing, but proceeds immediately to another take-off. This is a frequent practice when learning takeoffs and landings, provided the runway length is long enough to do so safely.

VFR (Visual Flight Rules) - A defined set of FAA regulations and “rules of the road” covering operation of aircraft primarily by visual reference to the horizon (for aircraft control) and see-and-avoid procedures (for traffic separation). VFR is used by more than 70 percent of all flights; it is not, by definition, uncontrolled or out of control!