Glossary of Aviation Terms

Alphabetic links into the glossary

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

100LL

aviation gasoline, LL stands for low-lead

25-square

a power setting of 2500 rpm and 25 inches of manifold pressure. This setting is often used for climbing to cruise altitude, and in effect means running at a high power setting.

agl

above ground level

ailerons

control surfaces located on the trailing edges of the wings. Use of ailerons causes an aircraft to bank in one direction or the other by causing one wing to produce more lift and the other wing to produce less lift.

airway

airplanes can follow designated routes, defined by ground-based navigation devices. Such routes are termed "airways".

alternate air

an alternate source of air for the fuel-air mixture. An alternate air source is needed in situations where the normal air intake is blocked, such as by ice clogging the air intake screen.

Approach (ATC)

air traffic controllers working the air space around a large metropolitan area. Generally designated by the name of the city, such as Minneapolis Approach or Sioux Falls Approach.

approach

flying an aircraft according to the instructions on an approach plate (see next definition).

approach plates

detailed charts that allow a pilot to approach an airport and safely land under extremely poor visibility conditions. These approach plates provide information so that the pilot, utilizing both ground-based navigation devices and electronic equipment in the airplane, may fly without being able to see the ground.

base

airplanes fly very precise rectangular patterns around an airport prior to landing. Each side of the rectangle has a name. The base leg, as it is known, is flown at right angles to the runway, just before turning to the final direction for landing. Traffic patterns may be flown with either right-hand or left-hand turns.

bearing

direction or heading, expressed in terms of degrees from north. A heading of 0 is north; 180 is south; 360 is back to north again.

Beaver

not the animal! A type of aircraft, prized for freight work in the north country due to its large useful load capacity and ruggedness.

boost pump

an electrically-driven fuel pump that is used in some airplanes to supplement the engine-driven fuel pump. It is primarily used during starting, take-off, landing, and switching fuel tanks.

ceiling

a solid or almost solid overcast sky.

Center

the air taffic controllers working the enroute air space, as opposed to local controllers around a metropolitan area.

CFI

certified flight instructor

CFII

certified flight instructor instrument, a flight instructor rated to teach instrument flight (flight by instruments only, no outside visual references).

check ride

an applicant for a pilot's license must take a flight test with either the FAA or a designated examiner. For each new rating (classification), another flight test must be taken.

contact approach

the pilot accepts responsibility for a visual approach to an airport (aircraft under IFR control). In the U.S., pilots must request a contact approach.

controller

airplanes on instrument flight plans are under the control and watchful eye of an air traffic controller. In addition, all planes around large metropolitan areas are in communication with controllers.

convective

convective buildup refers to clouds with vertical development; thunderstorms, for example.

cowling

the removable cover over the front portion of the aircraft.

cumulus

clouds with vertical development as opposed to "layered" stratus-type clouds; thunderheads for example.

decision height

the minimum altitude to which an ILS approach may be flown (see ILS approach).

envelope

an aircraft's center of gravity and weight must fall within acceptable limits in order to be capable of safe flight. These limits are specified by the manufacturer and are referred to as the envelope.

FBO

fixed base operator. FBOs generally offer flight instruction, sell fuel, and maintain a fleet of aircraft for hire. In addition many of them offer repair service.

final

the last leg of the rectangular traffic pattern at an airport (see base leg). The one from which the aircraft descends to the runway.

flaps

Devices on the trailing edge of the wings that provide both lift and drag. They are used for landings and sometimes for takeoff and allow an aircraft to fly at a slower airspeed without stalling.

Flight Service

facilities that provide weather briefings and updates to pilots. See FSS.

FSS

flight service specialists provide weather briefing and updates to pilots. Pilots also file flight plans with FSS people who in turn transmit them to controllers.

Hobbs meter

an electrically-driven meter that records the duration of a flight in hours and fractions of hours.

hold

a racetrack pattern, one corner of which is fixed at a specific location. It is used to "park" a plane.

hood

any of a variety of devices used to restrict vision so that the pilot has no outside vision and can see only the aircraft instruments. It is used during instrument training in order to simulate conditions where the pilot cannot see outside the plane, such as being in a cloud.

ident

to ident a transponder - cause the transponder to send a special signal that results in a special display on a controller's radar screen. It is generally requested by a controller if an aircraft cannot be identified on the radar screen. (See transponder)

IFR

instrument flight rules. The pilot may be in clouds, flying solely by instruments, and therefore unable to see other aircraft. The controller takes the responsibility for aircraft separation.

ILS

instrument landing system. A precision ground-based navigation system that will guide the pilot to a safe landing in extremely poor visibility. ILS approaches are identified by the runway serve, so ILS-10 would indicate it is the ILS approach for runway 10.

IMC

instrument meteorlogical conditions; unable to see visual references outside the plane.

knots

nautical miles per hour. A nautical mile is 1.15 statute miles.

leading edges

the front portion, or edge, of the wing.

lenticular

standing lenticular is a type of cloud, often found over mountains. Often it remains stationary over the mountains, appearing to "stand" in one place. It gets its name from a "lens"-type appearance, and indicates extreme turbulence.

leaning

the pilot controls the fuel-to-air mixture. Decreasing the amount of fuel in the mixture is known as leaning.

Lycoming IO-540

a large six-cylinder airplane engine made by Lycoming.

MEA

minimum enroute altitude. The minimum altitude to fly on an airway and be assured of obstacle clearance and reception of navigation signals.

MEII

multi-engine instrument instructor, a CFII rated to teach instruments in a multi-engine aircraft.

MP

manifold presure is the measure of how much power is being generated or is available for use.

MVFR

marginal VFR, conditions between VFR and IFR. Generally defined as visibility between 3 and 5 miles, and ceilings between 1,000 and 3,000 feet.

needles

flying the aircraft strictly by reference to instruments, in other words by the needles on the navigation instruments.

nm

abbreviation for nautical miles.

OAT

outside air temperature. In Piper aircraft the OAT is generally a small probe at the top of the windshield.

on the gauges

flying in IMC conditions; unable to see visual references outside of the airplane, so flight takes place solely by reference to the instruments.

outer marker

the point at which the final descent towards the runway is started for certain types of instrument approaches. It is generally defined with a ground-based navigation device whose signal causes the marker beacons in the aircraft to light up.

pilotage

navigating to a destination by means of matching landmarks to aviation maps (as opposed to navigation by means of electronic equipment in the aircraft).

PIREP

a pilot report, sent in by enroute pilots to flight service, usually reporting any weather hazards or unusual conditions that might be of interest to other pilots.

pitot heat

a source of heat that can be applied to the pitot tube in order to keep it from icing shut. The pitot tube drives the airspeed indicator of the airplane by providing a source of ram air.

pre-flight

inspection of the aircraft prior to take-off. The pilot is ultimately responsible for the safety of the flight, so the pre-flight inspection should never be omitted.

radio

another name for Flight Service Station.

r-nav

a special type of avionics equipment aboard an aircraft that enables navigation to any point that is defined by a direction and a distance from a VOR. (See VOR)

rime ice

a type of ice that can form on aircraft surfaces.

RPM

revolutions per minute; how fast the engine crankshaft is turning.

rudder

the control surface on an aircraft that moves the tail in one direction or the other, causing the nose to yaw in one direction or the other.

squawk

the "reply" of a transponder device, transmitted when probed by a ground device. A unique code is transmitted from the aircraft back to the ground. (see transponder). Certain transponder codes have fixed meanings, for example a code of 7700 is used by an aircraft to indicate an emergency situation.

straight-in

omission of the standard rectangular traffic pattern for landing. Coming straight-in and landing. See traffic pattern.

Tanis heater

an engine block heater. A heating element is present in each cylinder plus one on the bottom of the block. It is plugged in, just like a car.

thermals

updrafts of air that cause unsmooth flight conditions.

transponder

a device aboard the aircraft that will reply to a ground-based probe signal. This reply makes the aircraft more visible on a controller's radar screen. The signal transmitted by a transponder is referred to as a squawk code.

threshold

the start of the runway when an airplane is landing. Planes fly over the threshold of the runway just prior to touching down (landing).

traffic pattern

airplanes fly very precise rectangular patterns around an airport prior to landing. Each side of the rectangle has a name. The leg flown parallel to the runway and opposite to the direction of landing is the downwind leg. The base leg, as it is known, is flown at right angles to the runway, just before turning to the final direction for landing. Traffic patterns may be flown with either right-hand or left-hand turns.

trough

a persistent area of low pressure, bringing low stratus clouds and precipitation.

uncontrolled (field)

an uncontrolled field is one without an operating control tower.

useable fuel

not all fuel is available. A certain small amount cannot be transferred from the fuel tanks to the engine.

VFR

visual flight rules. The pilot has the responsibility for seeing and avoiding other aircrft, towers, mountains, etc.

VOR

a ground-based navigation device that emits a signal that can be picked up by aircraft equipment and used for navigation.

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Copyright © 2003 Linda Dowdy, last revision 030224