Glossary
348 flying terms, in plain words. Each one names the FAA source it comes from.
#
100-hour inspection
An inspection due every 100 hours in service when an aircraft carries passengers for hire or is provided by its instructor for paid instruction. It may run 10 hours over to reach an inspection site.
14 CFR (eCFR), 14 CFR 91.409(b)
A
Accelerate-stop distance
The total runway a twin needs to speed up to the manufacturer's chosen speed, VR or VLOF, lose an engine at that moment, and then brake to a full stop.
Accelerated stall
A stall at a higher than normal airspeed because the load factor exceeds 1 G, as in a steep turn, abrupt pull-up, or overshooting the turn to final.
Acceleration error
A magnetic compass error on east or west headings: accelerating turns the card toward north and decelerating turns it toward south.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 8
Advection fog
Fog formed when moist air moves over colder ground or water and cools to its dewpoint. Common on coasts, it deepens with wind up to about 15 knots; stronger wind lifts it into low stratus.
Aviation Weather Handbook (FAA-H-8083-28), ch. 18.1.1.1.2
Adverse yaw
The nose's tendency to yaw away from the turn as ailerons are applied, because the rising wing makes more lift and therefore more induced drag. Rudder corrects it.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 6
Aeronautical decision-making (ADM)
A systematic way of thinking that pilots use to reliably choose the best course of action for the circumstances they face. It draws on risk management, hazardous-attitude awareness, and situational awareness.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary and ch. 2
Ailerons
The hinged control surfaces on the trailing edge of each wing, near the tip. One rises as the other lowers, rolling the airplane about its longitudinal axis.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 6
Air data computer (ADC)
An onboard computer that uses pitot pressure, static pressure, and outside air temperature to work out altitude, indicated and true airspeed, and air temperature for the flight displays.
Instrument Flying Handbook (FAA-H-8083-15B), glossary; IFH ch. 5
Air defense identification zone (ADIZ)
Airspace over land or water where, for national security, all aircraft must be readily identifiable, locatable, and controllable. Defense Department and law enforcement aircraft are exempt; 14 CFR part 99 sets the rules.
Pilot/Controller Glossary, Pilot/Controller Glossary; AIM 5-6
Air mass
A large body of air with fairly uniform temperature and moisture throughout. It takes on the character of the land or water region where it formed, called its source region.
Air traffic clearance
Permission from ATC for an aircraft to proceed under stated traffic conditions in controlled airspace. Its purpose is to prevent collisions between known aircraft.
14 CFR (eCFR), 14 CFR 1.1
Aircraft approach category
A grouping of aircraft by VREF, or 1.3 VSO at maximum certificated landing weight when no VREF is given, used to pick minimums. Category A is under 91 knots; B is 91 to under 121.
Instrument Procedures Handbook (FAA-H-8083-16B), glossary; P/CG; 14 CFR 97.3
Airfoil
A surface shaped to produce an aerodynamic force from the air moving past it. Wings, propeller blades, the rudder, and even trim tabs are all airfoils.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 4
Airmen's meteorological information (AIRMET)
An in-flight advisory meant for all pilots, especially VFR pilots and less capable aircraft, covering IFR conditions, mountain obscuration, moderate turbulence or icing, sustained surface winds over 30 knots, freezing levels, and low-level wind shear.
Airworthy
The condition of an aircraft that conforms to its type certificate and is in condition for safe operation. Both must be true, and the pilot in command decides whether it is safe to fly.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), ch. 9 (airworthiness certificate); 14 CFR 91.7
Alert area
Charted airspace that may hold heavy pilot training or unusual aerial activity, neither of which is hazardous. Pilots taking part and pilots passing through share equal responsibility for collision avoidance.
Pilot/Controller Glossary, Pilot/Controller Glossary (Special use airspace); AIM 3-4-6
Alternate airport
An airport listed in an IFR flight plan where the aircraft can land if landing at the intended destination becomes inadvisable.
Pilot/Controller Glossary, P/CG; IFH glossary
Alternate airport requirement
An IFR flight plan needs an alternate unless the destination has an instrument approach and, from 1 hour before to 1 hour after ETA, forecasts show at least a 2,000-foot ceiling and 3 miles visibility.
14 CFR (eCFR), 14 CFR 91.169(a)-(b)
Angle of attack (AOA)
The angle between the wing's chord line and the relative wind. The pilot changes it mainly with the elevator, and it largely determines how much lift the wing makes.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 5
Angle of incidence
The angle at which the wing is mounted on the airplane, measured between the wing's chord line and the airplane's longitudinal axis. It is not the same as angle of attack.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; AFH glossary
Annual inspection
A complete inspection every aircraft needs within the preceding 12 calendar months to be operated, unless an exception applies. It must be done by an A&P mechanic holding an Inspection Authorization, or another authorized person.
14 CFR (eCFR), 14 CFR 91.409(a); PHAK ch. 9
Antiauthority
The hazardous attitude of resenting rules and instructions, summed up as "Don't tell me." Its antidote is "Follow the rules; they are usually right."
Approach with vertical guidance (APV)
An approach that provides both lateral and vertical guidance but does not meet precision approach standards, such as LPV and LNAV/VNAV. It is flown to a DA.
Pilot/Controller Glossary, P/CG; AIM 5-4-5
Arm
The horizontal distance in inches from the datum to an item's center of gravity. Arms aft of the datum are positive, and forward arms are negative.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 10
Aspect ratio
How long and slender a wing is: its span divided by its average chord. A high aspect ratio wing makes less induced drag than a short, wide one.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 5
Atmospheric stability
The tendency of air to resist vertical motion. Lifted stable air sinks back to its original level, while unstable air keeps rising, favoring cumuliform clouds, turbulence, showers, and thunderstorms.
Attitude and heading reference system (AHRS)
A solid-state sensor unit that measures motion on all three axes and supplies attitude and heading data to electronic displays, replacing separate mechanical gyroscopic instruments.
Instrument Flying Handbook (FAA-H-8083-15B), glossary; IFH ch. 5
Attitude instrument flying
Flying the aircraft with the instruments, not the outside horizon, as the reference. The pilot sets attitude and power, then confirms the result on the other instruments.
Instrument Flying Handbook (FAA-H-8083-15B), glossary; IFH ch. 6
Autokinesis
A night illusion in which a stationary light seems to move after the pilot stares at it for a prolonged time. A pilot who tries to align with it may lose control.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary and ch. 17; AIM 8-1-5
Automatic direction finder (ADF)
An aircraft receiver that points toward a selected NDB, showing the direction to the station either relative to the aircraft's nose or as a magnetic bearing.
Pilot/Controller Glossary, P/CG; IFH glossary
Automatic terminal information service (ATIS)
A continuous recorded broadcast of routine, noncontrol information at busier airports, such as weather, runways in use, and NOTAMs, which reduces frequency congestion. Each update gets a new phonetic letter.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; AIM 4-1-13
Aviation routine weather report (METAR)
The standard coded surface observation at an airport, giving wind, visibility, weather, sky condition, temperature, dewpoint, and altimeter setting. A special report (SPECI) is issued when conditions change significantly.
Axes of an aircraft
Three imaginary lines through the center of gravity, each at right angles to the others: longitudinal (nose to tail, roll), lateral (wingtip to wingtip, pitch), and vertical (yaw).
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 5
B
Ballooning
An unwanted climb during the roundout, usually from raising the nose too fast. It is dangerous because the airplane gains height while nearing a stall.
Basic empty weight
The airplane's standard empty weight plus its installed optional and special equipment. It counts unusable fuel and full engine oil, but no usable fuel, people, or baggage.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 10
BasicMed
Flying without an FAA medical certificate using a U.S. driver's license, an FAA medical held after July 14, 2006 (not suspended or revoked), a course every 24 calendar months, and a physician exam every 48.
14 CFR (eCFR), 14 CFR 61.23(c)(3); 14 CFR 61.113(i)
BasicMed limitations
BasicMed limits: an aircraft certificated for at most 7 occupants and 12,500 pounds takeoff weight, at most 6 passengers, at or below 18,000 feet MSL and 250 KIAS, and within the U.S. unless authorized.
14 CFR (eCFR), 14 CFR 61.113(i)
Bearing
A horizontal direction to or from a point, measured clockwise through 360 degrees, usually from true north or magnetic north but sometimes from another reference.
Bernoulli's principle
The principle that a moving fluid's pressure drops as its speed rises. Faster airflow over the wing's curved upper surface lowers the pressure there and helps produce lift.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 4
Best angle of climb speed (VX)
The speed that gives the most altitude per unit of horizontal distance, so the climb is steepest. Pilots use it on a short-field takeoff to clear obstacles.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; AFH ch. 6
Best glide speed
The airspeed at which the airplane glides farthest for the altitude it loses with no engine power. Flying faster or slower than it steepens the glide.
Airplane Flying Handbook (FAA-H-8083-3C), glossary; ch. 9
Best rate of climb speed (VY)
The speed that gives the most altitude per unit of time, so the climb is fastest. It is the usual climb speed once obstacles are cleared.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; AFH ch. 6
Best rate of climb speed, one engine inoperative (VYSE)
The airspeed giving the most altitude gain per unit of time on one engine, or the least sink above the single-engine absolute ceiling. A blue radial line marks it.
Airplane Flying Handbook (FAA-H-8083-3C), glossary; ch. 13
C
Camber
The curvature of an airfoil's upper and lower surfaces. The top is curved more than the nearly flat bottom, so air flows faster over the wing than under it.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 4
Carbon monoxide poisoning
Hypoxia caused by a colorless, odorless, tasteless gas in engine exhaust that keeps blood from carrying oxygen. Suspect it with headache, drowsiness, or dizziness while the cabin heater is on.
Carburetor heat
An anti-icing system that routes heated air into the carburetor to prevent or melt carburetor ice. Using it richens the mixture and reduces power.
Carburetor icing
Ice that forms in the carburetor venturi and throttle valve as fuel vaporizes and pressure drops. It is likeliest below 70 degrees F with humidity above 80 percent, though warmer air can ice too.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), ch. 7; AFH glossary
Category
For pilot certificates and ratings, a broad grouping of aircraft, such as airplane, rotorcraft, glider, powered-lift, or lighter-than-air. For aircraft certification the word means something else, such as normal or utility.
14 CFR (eCFR), 14 CFR 1.1
CDI sensitivity
How far off course a full-scale needle deflection represents. With GPS it is 5 NM en route, 1 NM in terminal mode, and 0.3 NM at the final approach waypoint.
Aeronautical Information Manual, 1-1-17; IFH ch. 9
Ceiling
The height above ground of the lowest broken or overcast cloud layer, or the vertical visibility into a surface-based obscuration. Thin or partial layers do not count.
14 CFR (eCFR), 14 CFR 1.1; AWH ch. 24.4.3.9
Center of gravity (CG)
The single point through which the airplane's whole weight acts, so it would balance if hung there. It is given in inches from the datum or as a percent of mean aerodynamic chord.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 10
Center of pressure
The spot on the chord line where all of the wing's lift can be treated as acting. It is commonly called the center of lift.
Chandelle
A performance maneuver that turns 180 degrees while climbing, gaining the most altitude possible for the bank and power used, and ends wings level and nose high just above stall speed.
Changeover point (COP)
The point on an airway segment where the pilot switches navigation guidance from the station behind to the station ahead. It is charted when it is not at the midpoint.
Instrument Procedures Handbook (FAA-H-8083-16B), glossary; IFH glossary
Checkpoint
A prominent, easily identified landmark along a planned route, such as a town, highway junction, or lake, used to confirm position and check groundspeed and timing.
Chord line
An imaginary straight line through an airfoil from its leading edge to its trailing edge. Angle of attack and angle of incidence are both measured from it.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 5
Circling approach
A visual maneuver at the end of an instrument approach that lines up with a runway when a straight-in landing is not possible or desirable. It is flown at or above circling minimums.
Pilot/Controller Glossary, P/CG (Circle-to-land maneuver); IFH glossary
Class
For pilot certificates and ratings, a grouping of aircraft within a category that have similar operating characteristics, such as single-engine land, multiengine land, or single-engine sea.
14 CFR (eCFR), 14 CFR 1.1
Class A airspace
Airspace from 18,000 feet MSL through FL 600 over the 48 contiguous states and Alaska, including coastal waters out to 12 NM. All flights there operate under IFR unless ATC authorizes otherwise.
Pilot/Controller Glossary, Pilot/Controller Glossary (Controlled airspace); AIM 3-2-2
Class B airspace
Airspace generally from the surface to 10,000 feet MSL around the busiest airports, shaped in tailored layers like an upside-down wedding cake. Entry requires an ATC clearance, and all cleared aircraft receive separation service.
Pilot/Controller Glossary, Pilot/Controller Glossary (Controlled airspace); AIM 3-2-3
Class C airspace
Airspace generally from the surface to 4,000 feet above a towered airport with radar approach control, typically a 5 NM core and a 10 NM shelf starting at 1,200 feet. Entry requires two-way radio communication.
Pilot/Controller Glossary, Pilot/Controller Glossary (Controlled airspace); AIM 3-2-4
Class D airspace
Airspace generally from the surface to 2,500 feet above airport elevation around an airport with an operating control tower. Pilots must establish two-way radio communication with the tower before entering.
Pilot/Controller Glossary, Pilot/Controller Glossary (Controlled airspace); AIM 3-2-5
Class E airspace
Controlled airspace that is not Class A, B, C, or D. It begins at the surface or a set altitude, often 700 or 1,200 feet AGL, and includes federal airways and transition areas.
Pilot/Controller Glossary, Pilot/Controller Glossary (Controlled airspace); AIM 3-2-6
Class G airspace
Uncontrolled airspace: whatever is not designated Class A, B, C, D, or E. ATC does not separate traffic there, but VFR weather minimums and other flight rules still apply.
Pilot/Controller Glossary, Pilot/Controller Glossary; AIM 3-3-1
Clear air turbulence (CAT)
Turbulence in cloudless air, usually at high altitude near the jet stream where strong wind shear exists. It gives no visual warning, so pilot reports are the best source of information about it.
Aeronautical Information Manual, 7-1-23; AWH ch. 19.2.3.2
Clear ice
Glossy, clear, or translucent ice formed when large supercooled droplets freeze slowly and flow back over the surface before freezing. It is hard to see, can form horns, and is difficult to remove.
Aviation Weather Handbook (FAA-H-8083-28), ch. 20.3.2
Clearance limit
The fix, point, or location to which ATC has cleared an aircraft. The pilot may not proceed beyond it without further clearance.
Pilot/Controller Glossary, P/CG; AIM 4-4-3
Climb gradient
A required rate of climb over distance, stated in feet per nautical mile. Departure obstacle clearance assumes at least 200 feet per NM unless a procedure publishes a steeper gradient.
Cold front
A front where colder, denser air advances and wedges under warmer air, forcing it up steeply. It often brings a narrow band of showers or thunderstorms, gusty winds, and a sharp temperature drop.
Aviation Weather Handbook (FAA-H-8083-28), ch. 11.3.2
Complex airplane
An airplane with retractable gear, flaps, and a controllable-pitch propeller (FADEC may stand in for the propeller); a seaplane needs just flaps and that propeller. Acting as PIC requires logged training and a one-time endorsement.
14 CFR (eCFR), 14 CFR 61.1; 14 CFR 61.31(e)
Compulsory reporting point
A fix that must be reported to ATC when passed, shown on charts by a solid triangle. Position reports there stop once ATC says the aircraft is in radar contact.
Constant-speed propeller
A propeller whose governor adjusts blade angle automatically to hold the engine rpm the pilot selects with the propeller control, even as air loads change.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 7
Contact approach
A pilot-requested, ATC-authorized approach in which an IFR aircraft, clear of clouds with 1 mile flight visibility, leaves the procedure and flies visually. Reported ground visibility must be at least 1 SM.
Pilot/Controller Glossary, P/CG; IPH glossary; AIM 5-4-25
Control and performance method
A method of attitude instrument flying in which the pilot sets attitude and power on the control instruments, then checks the performance instruments to see whether the result is what was wanted.
Instrument Flying Handbook (FAA-H-8083-15B), glossary; IFH ch. 6
Control instruments
The instruments that show attitude and power directly: the attitude indicator plus power gauges such as the tachometer, manifold pressure, or fuel flow. Pilots make all adjustments by reference to them.
Instrument Flying Handbook (FAA-H-8083-15B), ch. 6 (Control Instruments)
Controlled airspace
Airspace of set dimensions in which ATC service is given to IFR flights, and to VFR flights as the airspace class allows. The term covers Class A, B, C, D, and E airspace.
14 CFR (eCFR), 14 CFR 1.1
Conventional landing gear
Landing gear with two main wheels ahead of the CG and a third wheel at the tail, also called tailwheel gear. Because the CG is behind the mains, ground loops are a risk.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 7
Coordinated flight
Flight with no slip or skid: the nose points straight into the relative wind and the ball is centered, because the pilot uses rudder to offset yaw from power, aileron, and turning.
Airplane Flying Handbook (FAA-H-8083-3C), ch. 5; PHAK glossary
Coriolis illusion
A strong false sense of rotation or tumbling on a different axis, caused by moving the head abruptly during a long constant-rate turn after the inner ear has stopped sensing that turn.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary and ch. 17
Counter-rotating propellers
Propellers that turn in opposite directions, with the right one turning counterclockwise. Asymmetric thrust is the same with either engine failed, so neither engine is critical.
Course
The intended direction of flight in the horizontal plane, measured in degrees from north. The word also names an ILS localizer path, such as the front course or back course.
Crab
A wind-correction method in which the airplane's heading is turned into the wind just enough that its ground track stays on the desired course despite a crosswind.
Airplane Flying Handbook (FAA-H-8083-3C), glossary; ch. 9
Crew resource management (CRM)
Team management applied on the flight deck so crews make effective use of all available people, equipment, and information. It extends to dispatchers, cabin crew, maintenance personnel, and air traffic controllers.
Critical angle of attack
The angle of attack beyond which the wing stalls. For a given wing it is the same at any airspeed, flight attitude, or weight.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 5
Critical engine
The engine whose failure most hurts directional control. On twins with both propellers turning clockwise, as seen from the cockpit, it is the left engine, because the right engine's descending blade has the longer arm.
Airplane Flying Handbook (FAA-H-8083-3C), glossary; ch. 13
Cross-control stall
A stall with aileron applied one way and rudder the other, often from a skidding base-to-final turn. It can roll the airplane over and quickly become a spin.
Cross-country time
Flight time with a landing away from the departure point, using navigation. For private, commercial, or instrument experience (not rotorcraft), a landing must be more than 50 NM straight-line from the original departure point.
14 CFR (eCFR), 14 CFR 61.1
Crosswind component
The part of the wind, in knots, that blows at 90 degrees to the runway. The maximum demonstrated crosswind component is published in the AFM/POH.
Airplane Flying Handbook (FAA-H-8083-3C), glossary; PHAK ch. 11
Cruise clearance
A clearance for any altitude from the minimum IFR altitude up to a stated altitude. Once a pilot reports leaving an altitude in descent, returning needs clearance. It also authorizes an approach at destination.
Pilot/Controller Glossary, P/CG (CRUISE); AIM 4-4-3
D
Datum
The imaginary vertical plane the manufacturer picks as the zero point for weight and balance. Every arm, and the CG range, is measured in inches from it.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 10
Dead reckoning
Navigation by computing heading, groundspeed, and time en route from airspeed, course, and wind, then holding those values to fly from one point to another.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary and ch. 16
DECIDE model
A six-step decision process: Detect a change, Estimate the need to react, Choose a desirable outcome, Identify actions to reach it, Do the necessary actions, and Evaluate their effect.
Decision altitude (DA)
The altitude MSL on an approach with an electronic glidepath, such as an ILS or LPV, at which the pilot must begin a missed approach if the required visual references are not in sight.
Pilot/Controller Glossary, P/CG; IPH glossary; IFH glossary
Decision height (DH)
The decision point on a precision approach expressed as height above the runway threshold. Category II and III minimums use DH, measured by radio altimeter.
Pilot/Controller Glossary, P/CG; IPH glossary
Decompression sickness (DCS)
Illness caused when nitrogen dissolved in the body forms bubbles as pressure drops. After scuba diving without decompression stops, wait at least 12 hours before flying up to 8,000 feet, and 24 hours above that.
Density altitude
Pressure altitude corrected for nonstandard temperature. High density altitude means thinner air, which reduces engine power, propeller thrust, and lift.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 4, 11
Descend via
An ATC clearance to fly a published procedure's lateral path and speed restrictions, with descent at the pilot's discretion as long as every published altitude restriction is met.
Pilot/Controller Glossary, P/CG; IPH glossary
Detonation
An uncontrolled, explosive burning of the fuel-air charge after it reaches its critical pressure and temperature, instead of a smooth burn. It can quickly damage the engine.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 7
Deviation
Compass error produced by magnetic fields inside the airplane, from things like radios and wiring. It differs on each heading and is listed on the compass correction card.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 8
Dewpoint
The temperature to which air must be cooled, with pressure and moisture content unchanged, for its water vapor to condense into liquid. Below freezing it is sometimes called the frost point.
Dihedral
The upward angle of the wings from root to tip, relative to the lateral axis. It is a main contributor to lateral stability.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 5
Direct entry
A holding pattern entry in which the pilot flies directly to the fix and turns to follow the pattern. It is the recommended entry for the largest of the three entry sectors.
Aeronautical Information Manual, 5-3-8 (entry procedures)
Directional stability
Stability in yaw, about the vertical axis: the airplane's natural tendency to swing back into line with the relative wind after a disturbance. The vertical tail provides most of it.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 5
Displaced threshold
A runway threshold located somewhere other than the start of the runway. The pavement before it may be used for takeoff in either direction and for landing rollout from the opposite direction.
Aeronautical Information Manual, 2-3-3; Pilot/Controller Glossary
Distance measuring equipment (DME)
Airborne and ground equipment that shows the distance in nautical miles between the aircraft and a ground station. The reading is slant range, not horizontal distance.
Pilot/Controller Glossary, P/CG; AIM 1-1-7
Diverse departure
A departure from a runway where the obstacle assessment shows an aircraft may turn in any direction after takeoff and remain clear of obstacles, so no ODP is published.
Drag
The aerodynamic force that resists the airplane's motion, acting in the same direction as the relative wind. It is the total of parasite drag and induced drag.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 5
Dry adiabatic lapse rate
The rate at which rising unsaturated air cools from expansion, about 3 °C per 1,000 feet. Sinking unsaturated air warms by compression at the same rate.
Dynamic stability
The airplane's behavior over time after a disturbance. With positive dynamic stability the oscillations shrink and it settles back toward equilibrium; neutral means they stay the same, negative means they grow.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 5
E
Eights on pylons
The most advanced ground reference maneuver: a figure eight around two pylons, with altitude changed to stay at pivotal altitude so the reference line stays on each pylon.
Elevator
The movable control surface hinged to the trailing edge of the horizontal stabilizer. It pitches the airplane about the lateral axis and is how the pilot changes angle of attack.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 6
Empennage
The airplane's tail assembly: the fixed vertical and horizontal stabilizers together with the movable surfaces attached to them, such as the rudder, elevator, and trim tabs.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 3
Emphasis
A cross-check error in which the pilot gives one instrument too much weight and trusts it alone, rather than reading the group of instruments that together show attitude and performance.
Instrument Flying Handbook (FAA-H-8083-15B), glossary (Emphasis error); IFH ch. 6
Expect further clearance time (EFC)
The time at which a pilot should expect further clearance past a clearance limit. ATC issues it with holding instructions, and it sets when to leave the limit if communications are lost.
Pilot/Controller Glossary, P/CG; AIM 4-4-3; 14 CFR 91.185
F
Feathering
Turning a failed engine's propeller blades parallel to the airflow so the propeller stops and drag is greatly reduced. On most twins, counterweights drive the blades toward feather when governor oil pressure is removed.
Airplane Flying Handbook (FAA-H-8083-3C), glossary; ch. 13
Featureless terrain illusion
An illusion of being higher than actual when approaching over water, dark areas, or snow-covered ground lacking visible features. It leads pilots to fly a too-low approach and is sometimes called the black-hole approach.
Feeder route
A route shown on approach charts, with a course, distance, and minimum altitude, that takes aircraft from the en route structure to the initial approach fix. It is not one of the approach segments.
Pilot/Controller Glossary, P/CG; IPH glossary
Final approach fix (FAF)
The fix where the final approach segment begins. Charts mark it with a Maltese cross on nonprecision approaches; on precision approaches the lightning bolt glideslope intercept point serves this role.
Pilot/Controller Glossary, P/CG; IFH glossary
Final approach segment
The last part of an instrument approach, running from the final approach fix or point to the runway, airport, or missed approach point. The aircraft aligns with the runway and descends to land.
Pilot/Controller Glossary, P/CG (Segments of an Instrument Approach Procedure)
Fixation
A cross-check error in which the pilot stares at one instrument and stops scanning the rest, so deviations shown elsewhere, such as a slow heading change, go unnoticed.
Instrument Flying Handbook (FAA-H-8083-15B), glossary (Fixating); IFH ch. 6 (Common Errors)
Fixed-pitch propeller
A propeller with a blade angle that cannot be changed. It is a compromise, efficient at only one combination of airspeed and rpm; the throttle controls rpm.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 7
Flaps
Hinged sections on the wing's trailing edge between the ailerons and fuselage. Extending them increases camber, lift, and drag, allowing a slower and steeper approach.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 6
Flight following
Common name for radar traffic advisories given to VFR pilots on request, as controller workload permits. The pilot still navigates, avoids weather, and remains responsible for seeing and avoiding other aircraft.
Pilot/Controller Glossary, Pilot/Controller Glossary (Traffic advisories); AIM 4-1-15
Flight time
Pilot time that starts when an aircraft first moves under its own power intending to fly and ends when it stops after landing. For a glider without self-launch, it starts when the tow begins.
14 CFR (eCFR), 14 CFR 1.1
Flight visibility
How far ahead, on average, a pilot in flight can see and identify prominent objects horizontally: unlighted ones by day, lighted ones by night. Most VFR visibility minimums are stated in flight visibility.
14 CFR (eCFR), 14 CFR 1.1
Floating
A landing fault in which the airplane keeps flying just above the runway instead of settling, because it has too much airspeed. It uses up runway and makes the touchdown point hard to predict.
Airplane Flying Handbook (FAA-H-8083-3C), glossary; ch. 9
Fly-by waypoint
A waypoint where the navigation system starts the turn before reaching it, anticipating the turn so the aircraft does not overshoot the next leg.
Instrument Procedures Handbook (FAA-H-8083-16B), glossary; AIM 1-2-1
Fly-over waypoint
A waypoint the aircraft must cross before starting any turn. After passing it, the aircraft intercepts the next leg or proceeds direct to the next waypoint.
Instrument Procedures Handbook (FAA-H-8083-16B), glossary; AIM 1-2-1
Forward slip
A slip that keeps the airplane's direction of travel the same while its longitudinal axis is angled to the flight path. It steepens the descent without adding airspeed.
Airplane Flying Handbook (FAA-H-8083-3C), glossary; ch. 9
Front
The boundary or transition zone between two air masses of different temperature and density. Most significant weather develops along fronts, which typically bring wind shifts, temperature changes, and falling then rising pressure.
Frost
Ice crystals that form directly from water vapor on a surface when its temperature and the dewpoint are both below freezing. Even thin frost on the wings disrupts airflow and must be removed before takeoff.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary and ch. 12
Fuel injection
A fuel metering system that sprays fuel into the intake port of each cylinder instead of using a carburetor. It is less prone to induction icing.
Airplane Flying Handbook (FAA-H-8083-3C), glossary; PHAK ch. 7
G
Glideslope (GS)
The ILS component that provides vertical guidance on final approach. The beam is normally set at 3 degrees and is usable to 10 NM unless otherwise certified.
Pilot/Controller Glossary, P/CG; AIM 1-1-9
Go-around
Abandoning a landing approach and climbing away, also called a balked landing. The pilot adds power, sets climb pitch, and cleans up the configuration in order.
Airplane Flying Handbook (FAA-H-8083-3C), glossary; ch. 9
Graveyard spiral
An illusion that a prolonged, coordinated, constant-rate turn has stopped. The disoriented pilot then loses altitude in the turn and may tighten it into a steep descending spiral.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary and ch. 17
Ground effect
Reduced induced drag and more lift when flying within about one wingspan of the surface, because the ground restricts the wing's upwash, downwash, and wingtip vortices.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 5
Ground loop
A sharp, uncontrolled turn on the ground, most common in tailwheel airplanes. It can tip the airplane until the outside wingtip strikes the ground.
Airplane Flying Handbook (FAA-H-8083-3C), glossary; ch. 9
Groundspeed (GS)
The actual speed of the aircraft over the ground: true airspeed increased by a tailwind component or reduced by a headwind component.
Gyroscopic precession
The property of a spinning body that makes an applied force take effect 90 degrees ahead in the direction of rotation. For propellers it peaks as a tailwheel airplane raises its tail on takeoff.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 5
H
Hazardous attitudes
Five attitudes that undermine pilot judgment: antiauthority, impulsivity, invulnerability, macho, and resignation. Each has an antidote statement a pilot can use to counter it.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary and ch. 2
High-performance airplane
An airplane with any engine rated at more than 200 horsepower. Acting as its pilot in command takes logged ground and flight training plus a one-time logbook endorsement from an authorized instructor.
14 CFR (eCFR), 14 CFR 61.31(f)
Histotoxic hypoxia
Hypoxia in which enough oxygen reaches the cells but they cannot use it, usually because of alcohol, narcotics, or poisons.
Hold-in-lieu of procedure turn (HILPT)
A holding pattern at a final or intermediate fix that replaces a procedure turn. It is required unless the pilot is vectored to final, on a NoPT route, cleared straight-in, or flying a timed approach.
Pilot/Controller Glossary, P/CG; AIM 5-4-9
Holding fix
The fix, located by navaids or by visual reference to the ground, that a holding pattern is built around and that the pilot uses to stay in the pattern.
Holding pattern
A racetrack course of two turns and two straight legs that keeps an aircraft in protected airspace at a fix while it waits for further clearance. Standard holds turn right; nonstandard holds turn left.
Instrument Flying Handbook (FAA-H-8083-15B), glossary; AIM 5-3-8
Horizontal situation indicator (HSI)
An instrument that combines a heading indicator with a course deviation indicator, and often a glideslope display, so the pilot sees heading and position relative to the selected course together.
Instrument Flying Handbook (FAA-H-8083-15B), glossary; IFH ch. 5
Hypemic hypoxia
Hypoxia in which the blood cannot take up and carry enough oxygen, from causes such as anemia, blood loss, or recent blood donation. Carbon monoxide poisoning is its most common form.
Hyperventilation
Breathing faster or deeper than needed, often from stress or fear, which drives too much carbon dioxide from the body. Symptoms resemble hypoxia and fade once breathing is consciously slowed.
Aeronautical Information Manual, 8-1-3; PHAK ch. 17
Hypoxia
A lack of oxygen in the body severe enough to impair the brain and other organs. Symptoms are subtle and differ between people, and judgment often suffers before the pilot notices anything wrong.
Hypoxic hypoxia
Hypoxia caused by too little oxygen reaching the lungs, as at altitude where lower air pressure keeps enough oxygen from passing into the blood. It is the type most associated with flying.
I
IFR clearance
ATC authorization to fly under IFR. It normally contains the clearance limit, departure procedure, route of flight, altitude, and holding instructions when a delay is expected.
Impulsivity
The hazardous attitude of acting immediately without stopping to think, summed up as "Do it quickly." Its antidote is "Not so fast; think first."
IMSAFE checklist
A personal fitness check before flight covering Illness, Medication, Stress, Alcohol, Fatigue, and Emotion. A problem in any area is a reason to reconsider flying.
Inbound leg
The leg of a holding pattern flown toward the holding fix. In a timed hold it is 1 minute at or below 14,000 feet MSL and 1 1/2 minutes above that.
Aeronautical Information Manual, 5-3-8 (Timing)
Indicated airspeed (IAS)
The speed shown on the airspeed indicator itself, with no correction for instrument or installation error. Takeoff, landing, and stall speeds in the POH are normally indicated airspeeds.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 8; AFH glossary
Induced drag
Drag created as a by-product of making lift. It increases as airspeed decreases, because slower flight needs a higher angle of attack.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 5
Initial approach fix (IAF)
A fix shown on an approach chart where an initial approach segment begins and the procedure can be started. Charts label it IAF, and a procedure may have several.
Pilot/Controller Glossary, P/CG; IFH glossary
Initial approach segment
The first part of an instrument approach, running from the initial approach fix to the intermediate fix, or to where the aircraft is established on the intermediate or final course.
Pilot/Controller Glossary, P/CG (Segments of an Instrument Approach Procedure)
Instrument approach procedure (IAP)
A published sequence of maneuvers that brings an aircraft flying under IFR from the start of the initial approach to a landing, or to a point where the pilot can land visually.
Pilot/Controller Glossary, P/CG; IFH glossary
Instrument cross-check
The continuous scan of the control and performance instruments, with each indication interpreted, so the pilot always knows the aircraft's attitude and performance. Also called scanning.
Instrument Flying Handbook (FAA-H-8083-15B), ch. 6 (Instrument Cross-Check)
Instrument landing system (ILS)
A precision approach system that normally includes a localizer, glideslope, marker beacons, and approach lights, giving both lateral and vertical guidance to a specific runway.
Instrument Procedures Handbook (FAA-H-8083-16B), glossary; IFH glossary; AIM 1-1-9
Instrument meteorological conditions (IMC)
Weather in which visibility, distance from clouds, or ceiling falls below the VMC minimums, so flight in controlled airspace must be conducted under IFR.
Pilot/Controller Glossary, P/CG; IFH glossary
Intermediate approach segment
The part of an instrument approach between the intermediate fix or point and the final approach fix, where the aircraft is aligned and slowed for final.
Pilot/Controller Glossary, P/CG (Segments of an Instrument Approach Procedure); IPH ch. 4
Intermediate fix (IF)
The fix that marks the start of the intermediate approach segment. Charts often do not label it as an IF.
Invulnerability
The hazardous attitude of believing accidents happen only to others, summed up as "It won't happen to me." Its antidote is "It could happen to me."
Isogonic line
A line on an aeronautical chart connecting points that have the same magnetic variation, labeled with that variation for use in converting true course to magnetic course.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary and ch. 16
L
Lateral stability
Stability in roll, about the longitudinal axis. When a gust drops one wing, a laterally stable airplane tends to roll back toward wings level on its own.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 5
Lazy eight
A performance maneuver of two 180 degree turns in opposite directions, with a climb and descent in each, so the nose traces a figure eight on its side.
Lift
The aerodynamic force a wing produces at right angles to the relative wind. In steady flight it opposes weight.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 5
Lift/drag ratio (L/D)
How efficiently a wing makes lift, found by dividing lift by drag at a given angle of attack. At maximum L/D the airplane flies with the least total drag.
Airplane Flying Handbook (FAA-H-8083-3C), glossary (L/D, minimum drag speed); PHAK ch. 5
Load factor
The load the wings carry compared with the airplane's actual weight, stated in Gs. A level, coordinated turn at 60 degrees of bank puts it at 2 Gs.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 5; AFH glossary
Localizer (LOC)
The ILS component that provides lateral guidance along the runway centerline. Its course is adjusted to be 700 feet wide at the runway threshold.
Pilot/Controller Glossary, P/CG; IFH glossary; AIM 1-1-9
Localizer performance with vertical guidance (LPV)
A line of minimums on RNAV (GPS) approaches that uses WAAS for localizer-like lateral guidance and an electronic glidepath. It is an approach with vertical guidance and is flown to a DA.
Pilot/Controller Glossary, P/CG; AIM 5-4-5; IPH glossary
Longitudinal stability
Stability in pitch, about the lateral axis. When a disturbance pitches the nose up or down, a longitudinally stable airplane works its way back to the angle of attack it was trimmed for.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 5
Lost communications
Loss of two-way radio contact under IFR. In VFR conditions, continue VFR and land when practicable; otherwise fly the assigned, vectored, expected, or filed route at the highest of assigned, minimum, or expected altitude.
14 CFR (eCFR), 14 CFR 91.185; P/CG
Low-level wind shear (LLWS)
Wind shear within about 2,000 feet of the ground, produced by thunderstorms and microbursts, passing fronts, temperature inversions, or strong winds aloft. It is most dangerous during takeoff, approach, and landing.
Aviation Weather Handbook (FAA-H-8083-28), ch. 19.2.4.1 and 19.2.4.2
M
Macho
The hazardous attitude of taking risks to prove ability or impress others, summed up as "I can do it." Its antidote is "Taking chances is foolish."
Magnetic heading (MH)
The direction the aircraft's nose points measured from magnetic north. It equals true heading corrected for magnetic variation.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary and ch. 16
Magnetic variation
The angle between true north and magnetic north at a given location. It changes with location, not heading; when converting true to magnetic, subtract east variation and add west.
Magneto
An engine-driven unit that makes the high voltage for the spark plugs, independent of the airplane's electrical system. Most engines have two for safety.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 7
Magnetometer
A sensor that detects the Earth's magnetic field and sends heading information to the AHRS. If it fails, the pilot uses the magnetic compass for heading.
Instrument Flying Handbook (FAA-H-8083-15B), ch. 5 and ch. 7 (Compass Turns); PHAK ch. 8
Maneuvering speed (VA)
The design maneuvering speed: below it, one full deflection of a single control, in smooth air, will not damage the airplane. It is lower at lighter weights and does not cover repeated or combined inputs.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 5; AFH glossary
Manifold pressure (MP)
The absolute pressure in the engine's intake manifold, read in inches of mercury. With a constant-speed propeller it shows power output, which the pilot sets with the throttle.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary (manifold absolute pressure); AFH glossary; PHAK ch. 7
Marker beacon
A low-power transmitter that sends a narrow signal straight up, giving an aural and visual cue when the aircraft passes over it on an approach, such as the outer marker.
Instrument Flying Handbook (FAA-H-8083-15B), glossary; AIM 1-1-9
Maximum authorized altitude (MAA)
The highest usable altitude or flight level published for a route segment, the top of the band in which adequate reception of navigation signals is assured.
Pilot/Controller Glossary, P/CG; IPH glossary
Maximum holding airspeed
The fastest indicated airspeed allowed in holding: 200 knots up to 6,000 feet MSL, 230 knots from 6,001 to 14,000 feet, and 265 knots above 14,000 feet, unless charted otherwise.
Aeronautical Information Manual, 5-3-8 (airspeeds)
Microburst
A small, intense downdraft that spreads outward in all directions on reaching the ground, the most severe form of wind shear. It lasts about 5 to 15 minutes, with downdrafts up to 6,000 fpm.
Aviation Weather Handbook (FAA-H-8083-28), ch. 22.7.3; AIM 7-1-24
Military operations area (MOA)
Airspace set up to separate certain nonhazardous military training from IFR traffic and to show VFR pilots where it happens. VFR flight through it is allowed, but pilots should be especially watchful.
Pilot/Controller Glossary, Pilot/Controller Glossary (Special use airspace); AIM 3-4-5
Minimum control airspeed (VMC)
The lowest calibrated airspeed for directional control after the critical engine suddenly fails, with the other engine at takeoff power and up to 5 degrees of bank. A red radial line marks it.
Airplane Flying Handbook (FAA-H-8083-3C), glossary; ch. 13
Minimum crossing altitude (MCA)
The lowest altitude at which an aircraft must cross a certain fix when flying toward a higher MEA, set where obstacles prevent a normal climb after passing the fix.
Instrument Procedures Handbook (FAA-H-8083-16B), glossary; P/CG
Minimum descent altitude (MDA)
The lowest MSL altitude authorized on final approach or while circling, on a procedure with no electronic glideslope. The pilot stays at or above it until the required visual references are seen.
Pilot/Controller Glossary, P/CG; IPH glossary
Minimum en route altitude (MEA)
The lowest published altitude between radio fixes that both meets obstacle clearance requirements and assures acceptable navigation signal coverage for the whole segment.
Pilot/Controller Glossary, P/CG; IPH glossary; IFH glossary
Minimum IFR altitude
The lowest altitude for IFR flight. Where none is published, it is 2,000 feet above the highest obstacle within 4 NM of course in designated mountainous areas and 1,000 feet elsewhere.
14 CFR (eCFR), 14 CFR 91.177; P/CG (MIA)
Minimum obstruction clearance altitude (MOCA)
The lowest published altitude on a route segment that meets obstacle clearance requirements, but assures VOR signal coverage only within 22 NM of the VOR.
Pilot/Controller Glossary, P/CG; 14 CFR 91.177
Minimum reception altitude (MRA)
The lowest altitude at which an intersection can be identified using the navigation aids that define it.
Pilot/Controller Glossary, P/CG; IFH glossary
Minimum safe altitude (MSA)
An emergency altitude shown on approach and departure charts giving 1,000 feet of obstacle clearance within a set radius, normally 25 NM, of a facility or waypoint. It does not assure navigation signal coverage.
Aeronautical Information Manual, 5-4-5; IFH glossary
Minimum vectoring altitude (MVA)
The lowest MSL altitude a radar controller uses when vectoring IFR aircraft. It gives IFR obstacle clearance, can be below the MEA, and is normally shown only on controller charts.
Pilot/Controller Glossary, P/CG; IPH glossary
Missed approach
The maneuver flown when an instrument approach cannot be completed to a landing. The pilot follows the charted missed approach procedure or ATC instructions, first continuing along final to the missed approach point.
Instrument Flying Handbook (FAA-H-8083-15B), glossary; P/CG
Missed approach point (MAP)
The point on each instrument approach where the pilot must start the missed approach if the required visual references are not in sight. With vertical guidance, it is where the DA or DH is reached.
Pilot/Controller Glossary, P/CG; IFH glossary
Mixture
The proportion of fuel to air going into the cylinders. Air gets thinner with altitude, so the pilot leans the mixture in a climb to keep the proportion correct.
Airplane Flying Handbook (FAA-H-8083-3C), glossary; PHAK ch. 7
Mode C veil
The airspace within 30 NM of the primary airport of most Class B areas, from the surface to 10,000 feet MSL. Aircraft there generally need an altitude-reporting transponder and ADS-B Out.
Aeronautical Information Manual, 3-2-3; 14 CFR 91.215
Moment
An item's weight multiplied by its arm, in pound-inches. Total moment divided by total weight gives the CG location.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 10
Mountain wave
A wave pattern set up in strong winds blowing across a mountain ridge, producing strong updrafts, downdrafts, and turbulence above and downwind of the range. Lenticular or rotor clouds may mark it, but not always.
Aviation Weather Handbook (FAA-H-8083-28), ch. 16.2 and 19.2.2.1
N
Night
The period from the end of evening civil twilight to the start of morning civil twilight, per the Air Almanac and converted to local time. Night currency and position lights use different, sunset-based times.
14 CFR (eCFR), 14 CFR 1.1; 14 CFR 61.57(b); 14 CFR 91.209
No procedure turn (NoPT)
A chart label on a route or sector meaning the procedure turn or hold-in-lieu is not authorized. The pilot flies straight in and may reverse course only if ATC clears it.
Aeronautical Information Manual, 5-4-9; 14 CFR 91.175(j); IFH glossary
Nondirectional beacon (NDB)
A low or medium frequency radio beacon that transmits in all directions. An aircraft with an ADF can find its bearing to the station and home on or track to or from it.
Pilot/Controller Glossary, P/CG; IFH glossary
Nonprecision approach
An instrument approach with lateral guidance only and no electronic glideslope, such as VOR, NDB, localizer, or LNAV. Its minimums are an MDA.
Pilot/Controller Glossary, P/CG; IFH glossary
Northerly turning error
A magnetic compass error caused by magnetic dip. In the Northern Hemisphere the compass lags when a turn starts from a north heading and leads when it starts from south.
O
Obstacle departure procedure (ODP)
A published IFR departure, in text or graphic form, that gives obstacle clearance from the runway to the en route structure. Pilots may fly it without ATC clearance unless assigned a SID or vectors.
Pilot/Controller Glossary, P/CG; IPH ch. 1; AIM 5-2-9
Occluded front
A front formed when a faster cold front catches a warm front and lifts the warm air off the surface. Its weather combines features of both cold and warm fronts.
Aviation Weather Handbook (FAA-H-8083-28), ch. 11.3.4
Off-route obstruction clearance altitude (OROCA)
A charted altitude giving obstacle clearance of 1,000 feet in nonmountainous areas and 2,000 feet in designated mountainous areas within the U.S. It does not assure navigation, radar, or radio coverage.
Pilot/Controller Glossary, P/CG; IPH glossary
Omission
A cross-check error in which the pilot leaves an instrument out of the scan, often by failing to anticipate what it should show after an attitude change.
Instrument Flying Handbook (FAA-H-8083-15B), glossary (Omission error); IFH ch. 6
Outbound leg
The leg of a holding pattern flown away from the fix. Timing starts over or abeam the fix, whichever is later, and pilots adjust it so the inbound leg comes out to the correct length.
Aeronautical Information Manual, 5-3-8 (Timing)
P
P-factor
A left yaw at high angles of attack, caused by the descending propeller blade on the right taking a bigger bite of air and making more thrust than the ascending blade.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 5
Parallel entry
A holding pattern entry in which the pilot crosses the fix, flies parallel to the inbound course on the nonholding side for one minute, then turns back toward the holding side to rejoin.
Aeronautical Information Manual, 5-3-8 (entry procedures)
Parasite drag
Drag from the airplane moving through the air that does not help make lift, including form, interference, and skin friction drag. It increases as airspeed increases.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 5
Partial panel
Flying by instruments with some of them failed or covered, typically without the attitude and heading indicators, using the remaining instruments and the magnetic compass for control.
Instrument Flying Handbook (FAA-H-8083-15B), ch. 7 (Partial Panel Flight); IFH ch. 11
PAVE checklist
A preflight risk tool that sorts hazards into four groups: Pilot in command, Aircraft, enVironment, and External pressures.
Performance instruments
The instruments that show what the aircraft is actually doing as a result of attitude and power, such as the altimeter, airspeed indicator, vertical speed indicator, and heading indicator.
Instrument Flying Handbook (FAA-H-8083-15B), ch. 6 (Performance Instruments)
Pilot in command (PIC)
The pilot with final authority over and responsibility for the operation and safety of a flight, designated as such before or during the flight, and holding any category, class, or type rating the flight requires.
14 CFR (eCFR), 14 CFR 1.1
Pilot weather report (PIREP)
A report from a pilot of weather actually encountered in flight, such as cloud tops, turbulence, or icing. Routine and urgent reports help other pilots and forecasters confirm what is really happening aloft.
Pilot-controlled lighting
Airport lighting a pilot turns on by keying the microphone on a published frequency: 7 clicks within 5 seconds for highest intensity, 5 for medium, and 3 for lowest.
Pilotage
Navigation by visual reference to landmarks, comparing features seen on the ground with those shown on an aeronautical chart.
14 CFR (eCFR), 14 CFR 1.1; PHAK ch. 16
Pivotal altitude
The altitude, set by groundspeed, at which the line of sight along the wingtip to a ground point seems to pivot on that point. It is the basis of eights on pylons.
Airplane Flying Handbook (FAA-H-8083-3C), glossary; ch. 7
Porpoising
A series of bounces and dives along the runway after a nose-first touchdown or a poorly recovered bounce. Late control inputs can make it worse and damage the nose gear.
Airplane Flying Handbook (FAA-H-8083-3C), glossary; ch. 9
Precision approach
An instrument approach that provides an electronic glideslope or glidepath meeting precision standards, such as ILS, PAR, or GLS. Its minimums are a DA or DH.
Pilot/Controller Glossary, P/CG; IFH glossary
Precision approach path indicator (PAPI)
A single row of two or four lights, usually left of the runway, that gives visual glide path guidance. Two white and two red mean on path; more white means high, more red means low.
Preignition
Ignition of the fuel-air mixture before the spark plug fires, usually from a hot spot in the combustion chamber.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 7
Pressure altitude
Height above the standard datum plane, where pressure is 29.92 inches of mercury. It is the altimeter reading when 29.92 is set.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 4, 8; AFH glossary
Prevailing visibility
The greatest horizontal visibility that is equaled or exceeded around at least half of the horizon circle, which need not be one continuous arc. It is the visibility normally given in a METAR.
Pilot/Controller Glossary, Pilot/Controller Glossary (Visibility); AIM 7-1-15; AWH ch. 24.4.3.6
Preventive maintenance
Simple or minor upkeep and small standard part replacement without complex assembly (part 43 appendix A). Pilots may do it on aircraft they own or operate outside air carrier use; sport pilots, light-sport only.
14 CFR (eCFR), 14 CFR 1.1; 14 CFR 43.3(g); 14 CFR part 43 appendix A
Primary and supporting method
A method of attitude instrument flying that, for each of pitch, bank, and power, names the instrument giving the most direct information (primary) and the others that confirm trends (supporting).
Instrument Flying Handbook (FAA-H-8083-15B), glossary; IFH ch. 6
Primary instrument
The instrument that gives the most pertinent, direct indication for a given flight condition. In straight-and-level flight, the altimeter is primary for pitch and the heading indicator is primary for bank.
Instrument Flying Handbook (FAA-H-8083-15B), ch. 6 (Primary Pitch, Primary Bank)
Procedure turn (PT)
A charted maneuver to reverse direction onto the intermediate or final approach course. The chart sets the side, outbound course, distance limit, and minimum altitude; the pilot chooses the turn's style.
Pilot/Controller Glossary, P/CG; AIM 5-4-9
Prohibited area
Special use airspace, set up for security or other national welfare reasons, in which no one may fly without permission of the using agency. Prohibited areas are shown on aeronautical charts.
Pilot/Controller Glossary, Pilot/Controller Glossary (Special use airspace); AIM 3-4-2
R
Radial
A magnetic bearing extending outward from a VOR, VORTAC, or TACAN station. A VOR has 360 radials, each named for its magnetic direction from the station.
Pilot/Controller Glossary, P/CG; IFH glossary (Radials)
Radiation fog
Fairly shallow fog that forms over land on clear nights with light wind, as the chilled ground cools the air just above it to the dewpoint. It usually clears in the morning after sunrise.
Aviation Weather Handbook (FAA-H-8083-28), ch. 18.1.1.1.1
Readback
Repeating an ATC clearance or instruction back to the controller to confirm it was heard correctly. Read back altitudes, vectors, and runway assignments; controllers must get a readback of every runway hold short instruction.
Aeronautical Information Manual, 4-4-7 and 4-3-18; Pilot/Controller Glossary
Receiver autonomous integrity monitoring (RAIM)
A GPS receiver's self-check of signal integrity. It needs at least 5 satellites, or 4 plus barometric altimeter input, to detect a faulty satellite and warn the pilot.
Aeronautical Information Manual, 1-1-17; P/CG; IFH glossary
Rectangular course
A ground reference maneuver in which the airplane flies at a constant altitude and distance around a rectangular field, correcting for wind like a traffic pattern.
Region of reverse command
The slow-flight regime, also called the back side of the power curve, where holding altitude at a lower airspeed takes more power, and a higher airspeed takes less.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; AFH glossary; PHAK ch. 11
Relative wind
The airflow an airplane meets as it moves through the air. It always blows straight back along the flight path, opposite the direction of travel, so the flight path sets its direction.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 5
Resignation
The hazardous attitude of feeling unable to change the outcome, summed up as "What's the use?" Its antidote is "I'm not helpless; I can make a difference."
Restricted area
Special use airspace where flight is not banned outright but is restricted because of often invisible hazards such as artillery, aerial gunnery, or guided missiles. Entering while it is active requires authorization.
Pilot/Controller Glossary, Pilot/Controller Glossary (Special use airspace); AIM 3-4-3
Reverse sensing
A VOR or localizer display that moves opposite to the normal sense, so steering toward the needle takes the aircraft farther off course, as when the course selected is opposite the direction of flight.
Instrument Flying Handbook (FAA-H-8083-15B), glossary; IFH ch. 9
Right-of-way rules
Rules for who gives way. Distress has priority; when same-category aircraft converge at about the same altitude, the one on the right has right-of-way; head-on, both turn right; overtaken aircraft have right-of-way.
14 CFR (eCFR), 14 CFR 91.113
Rigidity in space
The tendency of a fast-spinning gyroscope to stay fixed in its plane of rotation. Attitude and heading indicators depend on it.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 8
Rime ice
Rough, milky, opaque ice formed when small supercooled droplets freeze instantly on impact, trapping air. It is the most frequently reported type of structural icing.
Aviation Weather Handbook (FAA-H-8083-28), ch. 20.3.1
Roundout
The gradual pitch-up just before touchdown that slows the descent and airspeed, moving the airplane from the approach attitude to the landing attitude. Also called the flare.
Airplane Flying Handbook (FAA-H-8083-3C), glossary; ch. 9
Rudder
The hinged surface on the trailing edge of the vertical fin, moved with the rudder pedals. It yaws the nose about the vertical axis and is used to keep flight coordinated.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 6
Runway holding position marking
Four yellow lines, two solid and two dashed, across a taxiway or runway that show where aircraft must stop before entering a runway. Aircraft hold on the side with the solid lines.
Runway incursion
An occurrence on or near a runway in which something on the ground (an aircraft, vehicle, person, or object) creates a collision risk or loss of required separation with an aircraft landing or taking off.
Runway width illusion
An illusion from unusual runway width: a narrow runway makes the aircraft seem high, inviting a low approach; a wide one makes it seem low, inviting a high flare and a hard or long landing.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), ch. 17; AIM 8-1-5
S
S-turns
A ground reference maneuver that crosses a straight line such as a road and flies a 180 degree constant-radius turn on each side, adjusting bank for wind so both halves match.
Safe, intentional one-engine-inoperative speed (VSSE)
The minimum speed at which a pilot may intentionally fail the critical engine, as in training. If none is published, use VYSE, the blue radial line speed.
Airplane Flying Handbook (FAA-H-8083-3C), glossary; ch. 13
Second-class medical certificate
The lowest medical class allowing commercial pilot privileges, apart from gliders and some balloon flying. For commercial privileges it lasts through the 12th month after the exam month, then serves private privileges like a third-class.
14 CFR (eCFR), 14 CFR 61.23(a) and (d)
Secondary stall
A stall that follows recovery from an earlier stall, usually because the pilot raises the nose too abruptly or tries to break the stall with power alone instead of lowering angle of attack.
Service ceiling
The highest density altitude where the airplane can still climb 100 feet per minute when flown at VY, at maximum weight, clean, with maximum continuous power.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; AFH glossary
Sideslip
A slip with the longitudinal axis parallel to the original path while the airplane drifts sideways toward the low wing. It is the wing-low crosswind landing method.
Airplane Flying Handbook (FAA-H-8083-3C), glossary; ch. 9
Sidestep maneuver
A visual maneuver at the end of an instrument approach that lets the pilot land straight in on a parallel runway lying no more than 1,200 feet to either side of the approach runway.
Pilot/Controller Glossary, P/CG; AIM 5-4-19
Significant meteorological information (SIGMET)
An in-flight advisory for weather hazardous to all aircraft, such as severe icing, severe or extreme turbulence, volcanic ash, or widespread dust or sandstorms cutting visibility below 3 miles. Thunderstorms get separate convective SIGMETs.
Pilot/Controller Glossary, Pilot/Controller Glossary; AWH ch. 26.2
Single-engine absolute ceiling
The altitude at which a twin with one engine inoperative can no longer climb at all. Above it, flying VYSE gives the slowest rate of descent.
Airplane Flying Handbook (FAA-H-8083-3C), glossary (absolute ceiling); ch. 13
Single-engine service ceiling
The altitude at which a twin with one engine inoperative can no longer hold a 50 foot per minute climb. The all-engine service ceiling uses 100 feet per minute.
Single-pilot resource management (SRM)
A pilot flying alone managing all available resources, such as equipment, automation, ATC, and passengers, so the flight ends safely.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary and ch. 2
Situational awareness
A pilot's accurate, up-to-date understanding of everything that bears on safety throughout a flight, from preflight to shutdown, across pilot, aircraft, environment, and the kind of operation.
Skid
An uncoordinated turn in which the rate of turn is too great for the bank angle, so the airplane is pushed toward the outside of the turn and the tail swings outside the nose.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary (skidding turn); AFH glossary
Slant range
The straight-line distance from the aircraft's antenna to a DME ground station, including the aircraft's height. It reads more than the horizontal distance, most noticeably when high and close to the station.
Aeronautical Information Manual, 1-1-7; IFH ch. 9
Slip
Flight in which the airplane moves partly sideways toward the low wing. Pilots slip on purpose to steepen a descent or correct for crosswind; unintended slips come from too little rudder.
Airplane Flying Handbook (FAA-H-8083-3C), glossary; ch. 9
Slow flight
Flying at an airspeed just above stall warning, about 5 to 10 knots above stall speed, at a high angle of attack where controls respond poorly and altitude is hard to hold.
Solo flight time
Flight time during which the pilot is the only occupant of the aircraft. A student pilot needs instructor endorsements before flying solo.
14 CFR (eCFR), 14 CFR 61.51(d); 14 CFR 61.87
Somatogravic illusion
A false sense of pitch caused by rapid acceleration or deceleration without visual references. Acceleration feels like a nose-up attitude, tempting the pilot to push the nose down.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary and ch. 17
Spatial disorientation
A pilot's mistaken sense of the aircraft's position, attitude, or motion in space. It usually happens when outside visual references are lost and the inner ear and body give false cues.
Special use airspace
Airspace where activities are confined because of their nature, where aircraft not involved face limits, or both. It includes prohibited, restricted, warning, military operations, alert, and controlled firing areas, and national security areas.
Pilot/Controller Glossary, Pilot/Controller Glossary; AIM 3-4-1
Special VFR (SVFR)
VFR flight below basic VFR minimums in the surface area of Class B, C, D, or E airspace, on pilot request and with ATC clearance. It requires clear of clouds and 1 SM flight visibility.
Pilot/Controller Glossary, Pilot/Controller Glossary (Special VFR operations); 14 CFR 91.157
Spin
An aggravated stall with autorotation, in which the airplane descends in a corkscrew path. It needs both a stall and yaw; its phases are entry, incipient, developed, and recovery.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; AFH ch. 5
Spiraling slipstream
The corkscrew of air behind the propeller that wraps around the fuselage and strikes the left side of the vertical fin, yawing the nose left. It is strongest at high power and low airspeed.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 5
Squawk
An ATC instruction to set a specific code, mode, or function on the transponder, such as squawk 1200 or squawk ident.
Pilot/Controller Glossary, Pilot/Controller Glossary
Stagnant hypoxia
Hypoxia caused when oxygen-rich blood does not flow adequately to the tissues, from causes such as heart problems, excessive G-forces, or cold temperatures that restrict circulation.
Stall
A sharp loss of lift when the wing exceeds its critical angle of attack and the airflow separates. It can happen at any airspeed or attitude; recovery starts by reducing angle of attack.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; AFH ch. 5
Standard alternate minimums
The forecast weather needed at arrival to list an airport as an alternate when none are published: 600-foot ceiling and 2 miles for a precision approach, 800-foot ceiling and 2 miles for nonprecision.
14 CFR (eCFR), 14 CFR 91.169(c)
Standard instrument departure (SID)
A published, graphic IFR departure procedure designed mainly to speed traffic flow and reduce pilot and controller workload. It also provides obstacle clearance and requires an ATC clearance to fly.
Pilot/Controller Glossary, P/CG; IPH glossary
Standard lapse rate
The average cooling with height assumed by the standard atmosphere: roughly 2 °C (3.5 °F) for every 1,000 feet of climb up to about 36,000 feet, above which temperature stays nearly constant.
Standard terminal arrival (STAR)
A published IFR arrival procedure that takes aircraft from the en route structure to a fix in the terminal area, simplifying clearance delivery. It often ends at an approach or with vectors.
Pilot/Controller Glossary, P/CG; IPH glossary
Standby instruments
Backup flight instruments, typically an attitude indicator, altimeter, airspeed indicator, and magnetic compass, installed for use when the primary flight display or its sensors fail.
Instrument Flying Handbook (FAA-H-8083-15B), ch. 11 (standby instrumentation)
Static stability
How an airplane first reacts when knocked out of equilibrium. Positive static stability means it starts back, neutral means it holds the new condition, and negative means it keeps moving away.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 5
Stationary front
A front that shows little or no movement because neither air mass is pushing the other aside. Its clouds and precipitation can linger over the same area for days.
Aviation Weather Handbook (FAA-H-8083-28), ch. 11.3.3
Steam fog
Fog that forms when very cold air moves over much warmer water, which evaporates and recondenses as rising streamers. The air in it is unstable, so expect low-level turbulence.
Aviation Weather Handbook (FAA-H-8083-28), ch. 18.1.1.1.5
Steep turn
In visual flight, a turn with more than 45 degrees of bank. It builds coordination and requires added back pressure and power to hold altitude.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; AFH ch. 10
Stepdown fix
A fix inside an approach segment marking where a controlling obstacle has been safely passed, so the pilot may descend to the next lower published altitude.
Pilot/Controller Glossary, P/CG; IFH glossary
Structural icing
Ice that builds up on the outside of the aircraft, such as wings, tail, and propeller, when flying through visible liquid moisture at or below freezing. It adds weight and drag and cuts lift.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; AWH ch. 20
Supporting instrument
An instrument that backs up the primary instrument by showing trends, such as the vertical speed indicator warning that altitude is starting to change before the altimeter shows much movement.
Instrument Flying Handbook (FAA-H-8083-15B), ch. 6 (supporting instruments)
T
Takeoff minimums
The weather required for an IFR takeoff, binding on Part 121, 125, 129, and 135 operators. If none are published, the standard is 1 SM with two engines or fewer, 1/2 SM with more.
14 CFR (eCFR), 14 CFR 91.175(f); IPH ch. 1
Teardrop entry
A holding pattern entry in which the pilot crosses the fix, flies a heading about 30 degrees off the outbound course into the holding side for one minute, then turns to intercept the inbound course.
Aeronautical Information Manual, 5-3-8 (entry procedures)
Temperature inversion
A layer of air in which temperature increases with altitude. It is very stable, tends to trap haze, smoke, and fog beneath it, and can produce wind shear at its boundary.
Aviation Weather Handbook (FAA-H-8083-28), ch. 5.8.3 and 19.2.3.1
Temperature-dewpoint spread
The difference between air temperature and dewpoint, also called dewpoint depression. A small or shrinking spread warns of fog or low clouds; fog seldom forms when it exceeds 2 °C (4 °F).
Aviation Weather Handbook (FAA-H-8083-28), ch. 6.6 and 18.1
Temporary flight restriction (TFR)
A temporary limit, issued by NOTAM, on flight within a defined area to protect people or property in the air or on the ground. Common causes include wildfires, disasters, VIP movements, and major sporting events.
Pilot/Controller Glossary, Pilot/Controller Glossary; AIM 3-5-3
Terminal aerodrome forecast (TAF)
A forecast of aviation-significant weather for a set period, usually 24 or 30 hours, covering the area within 5 statute miles of the center of an airport's runway complex. It uses METAR weather codes.
Terminal arrival area (TAA)
Airspace published with many RNAV approaches, divided into sectors with minimum altitudes giving at least 1,000 feet of obstacle clearance, so aircraft can fly from the en route structure direct to an IAF.
Instrument Procedures Handbook (FAA-H-8083-16B), glossary; P/CG; AIM 5-4-5
The leans
A false sense of banking in the opposite direction after an abrupt return to level flight from a gradual turn the inner ear never sensed. It is the most common illusion in flight.
Third-class medical certificate
The minimum medical for student, recreational, and private privileges, and for instructors acting as PIC, unless using BasicMed. It lasts 60 calendar months if under 40 at the exam, otherwise 24.
14 CFR (eCFR), 14 CFR 61.23(a) and (d)
Thrust
The forward force that moves the airplane, produced when a propeller or jet engine accelerates a mass of air rearward. It opposes drag.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 5
Thunderstorm life cycle
The three stages of a thunderstorm cell: towering cumulus, marked by strong updrafts; mature, which begins when precipitation reaches the surface; and dissipating, dominated by downdrafts. A cycle typically lasts about 30 minutes.
Time of useful consciousness
The time a pilot still has to make and carry out rational, life-saving decisions at a given altitude without supplemental oxygen. It shrinks rapidly above 10,000 feet, to seconds at very high altitude.
Torque
The airplane's reaction to the engine turning the propeller: a tendency to roll opposite the propeller's rotation. With a clockwise propeller, as seen from the cockpit, it rolls the airplane left.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 5
Touchdown zone elevation (TDZE)
The highest elevation within the first 3,000 feet of the landing surface. Approach charts list it wherever straight-in landing minimums are authorized, and HAT is measured from it.
Instrument Flying Handbook (FAA-H-8083-15B), glossary; P/CG (TOUCHDOWN ZONE ELEVATION)
Traffic advisory
An ATC alert about other known or observed aircraft close enough to a pilot's position or route to deserve attention. It never relieves the pilot of the duty to see and avoid traffic.
Pilot/Controller Glossary, Pilot/Controller Glossary; AIM 4-1-15
Transponder
The airborne part of the ATC radar beacon system: a receiver-transmitter that answers ground radar interrogations with a coded reply. In Mode C it also reports the aircraft's pressure altitude.
Pilot/Controller Glossary, Pilot/Controller Glossary; AIM 4-1-20
Tricycle gear
A landing gear layout with a nosewheel ahead of the two main wheels. It gives better visibility and directional control on the ground than tailwheel gear.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 7
Trim tab
A small hinged surface on a control surface that the pilot adjusts in flight to relieve control pressure, so the airplane holds its attitude without constant input.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 6
True airspeed (TAS)
The airplane's actual speed through the air: calibrated airspeed, which is indicated airspeed corrected for instrument and position errors, then corrected for pressure altitude and temperature.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 8
True course (TC)
The intended path over the ground, measured clockwise from true (geographic) north, as drawn and measured on an aeronautical chart.
True heading (TH)
The direction the aircraft's nose points measured from true north. It equals true course corrected by the wind correction angle needed to hold that course.
Turbocharger
An exhaust-driven compressor that raises the pressure of air going to the engine, so the engine can keep producing power at higher altitudes.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 7
Turn coordinator
A gyro instrument whose canted gimbal lets it show rate of roll, then rate of turn once the bank is steady. Its inclinometer ball shows whether the turn is coordinated.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 8
Turns around a point
A ground reference maneuver of consecutive 360 degree turns at a constant radius around a ground point. Bank is steepest downwind and shallowest upwind.
Type
For pilot ratings, a specific make and basic model of aircraft, including versions that fly and handle the same. Type ratings are needed for large aircraft, turbojet airplanes, powered-lift, and others the FAA designates.
14 CFR (eCFR), 14 CFR 1.1; 14 CFR 61.31(a)
U
Unusual attitude
Any aircraft attitude the pilot did not intend or expect, or an extreme one, such as a steep bank or a nose-high or nose-low pitch, that must be recognized and recovered on instruments.
Instrument Flying Handbook (FAA-H-8083-15B), glossary; IFH ch. 7
Upslope fog
Fog produced when wind pushes moist, stable air up rising terrain, cooling it adiabatically to its dewpoint. Unlike radiation fog it can form under an overcast, and it is often dense and deep.
Aviation Weather Handbook (FAA-H-8083-28), ch. 18.1.1.1.3
Useful load
Everything the airplane can carry beyond its basic empty weight: pilots, passengers, baggage, usable fuel, and drainable oil. It equals maximum allowable gross weight minus basic empty weight.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 10
V
V-G diagram
A graph of load factor against airspeed that applies to one weight, configuration, and altitude. It shows the most positive or negative G the wing can produce at each speed and the safe load limits.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 5
Vacuum system
The system that spins the attitude and heading indicator gyros: an engine-driven pump draws filtered air through the instruments, and a relief valve limits the suction.
Vacuum system failure
Loss of the engine-driven vacuum or pressure source that spins the gyros. The attitude and heading indicators slowly wander and fail, often with no warning other than the suction gauge.
Instrument Flying Handbook (FAA-H-8083-15B), ch. 11 (Pneumatic System Failure)
Victor airway
A low altitude airway based on VOR or VORTAC stations, charted as V plus a number, such as V12. It normally spans 1,200 feet AGL, sometimes higher, up to but not including 18,000 feet MSL.
Aeronautical Information Manual, 5-3-4; IFH glossary
Visibility
How far, in current conditions, prominent objects can be seen and identified: unlighted ones by day and lighted ones by night. It is reported in statute miles, hundreds of feet, or meters.
Pilot/Controller Glossary, Pilot/Controller Glossary
Visual approach
An ATC-authorized IFR approach flown visually and clear of clouds, with the airport or preceding aircraft in sight. Reported weather must be at least a 1,000-foot ceiling and 3 miles visibility.
Aeronautical Information Manual, 5-4-23; IPH glossary
Visual approach slope indicator (VASI)
A system of red and white light bars that gives visual descent guidance to a runway, normally on a 3 degree glide path. On a two-bar system, red over white means on the glide path.
Visual descent point (VDP)
A charted point on a nonprecision straight-in final from which a normal descent from the MDA to the touchdown point can start, provided the runway or its approach lights or markings are clearly in view.
Pilot/Controller Glossary, P/CG; IFH glossary; AIM 5-4-5
Visual meteorological conditions (VMC)
Weather in which visibility, distance from clouds, and ceiling are all at or better than the minimums set for VFR flight.
Pilot/Controller Glossary, P/CG; IFH glossary
VMC factors
The conditions that move actual VMC away from the published figure. VMC rises with more power on the good engine, a windmilling propeller, aft CG, lighter weight, gear up, and bank under 5 degrees.
VOR (VOR)
A ground-based VHF navigation aid whose signals, referenced to magnetic north, let a receiver tell which of 360 radials the aircraft is on. The station identifies itself in Morse code.
Pilot/Controller Glossary, P/CG (VOR); AIM 1-1-3
VOR receiver check
The accuracy check required within the preceding 30 days to use VOR for IFR. Limits are 4 degrees with a VOT or ground checkpoint and 6 degrees with an airborne checkpoint.
14 CFR (eCFR), 14 CFR 91.171; AIM 1-1-4; IFH glossary (VOT)
W
Wake turbulence
The pair of counter-rotating vortices trailing an aircraft's wings whenever they make lift. Strongest behind heavy, clean, slow aircraft, they sink several hundred feet per minute and drift with the wind.
Aeronautical Information Manual, 7-4; Pilot/Controller Glossary
Warm front
A front where warmer air advances and slides gradually up over retreating colder air. Ahead of it expect widespread layered clouds, steady precipitation, fog, and poor visibility.
Aviation Weather Handbook (FAA-H-8083-28), ch. 11.3.1
Warning area
Special use airspace extending outward from 3 NM off the U.S. coast that contains activity which may be hazardous to nonparticipating aircraft. It may lie over domestic waters, international waters, or both.
Pilot/Controller Glossary, Pilot/Controller Glossary (Special use airspace); AIM 3-4-4
Waypoint
A predetermined geographic position, defined by latitude and longitude or relative to a VORTAC, used to define routes and instrument approaches and to report progress.
Pilot/Controller Glossary, P/CG; IPH glossary
Weight
The downward force on the airplane caused by gravity. It acts through the center of gravity and is opposed by lift.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 5
Wide Area Augmentation System (WAAS)
A GPS augmentation system in which surveyed ground stations measure satellite errors and geostationary satellites broadcast corrections, improving accuracy and integrity and allowing approaches with vertical guidance.
Aeronautical Information Manual, 1-1-18; IFH glossary
Wind correction angle (WCA)
The number of degrees the heading must be turned into the wind, away from the desired track, so a crosswind does not push the airplane off that track.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; AFH ch. 7
Wind shear
A sudden, sharp change in wind speed, direction, or both over a short distance, either vertically or horizontally. It can occur at any altitude and is most dangerous close to the ground.
Aviation Weather Handbook (FAA-H-8083-28), ch. 19.2.4
Windmilling
A propeller turned by the airflow instead of the engine. At low pitch and high rpm, a windmilling propeller on a failed engine makes very high drag.
Airplane Flying Handbook (FAA-H-8083-3C), glossary; ch. 13
Winds and temperatures aloft forecast (FB)
A computer-made forecast of wind direction relative to true north, wind speed, and temperature at set altitudes over specific locations. Winds are omitted within 1,500 feet, and temperatures within 2,500 feet, of station elevation.
Aviation Weather Handbook (FAA-H-8083-28), ch. 27.2.1
Wingtip vortices
Spinning air that forms as high-pressure air under the wing curls around the tip into the low-pressure air above. They are strongest from heavy, clean, slow airplanes.
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), glossary; ch. 5
Z
Zero sideslip
The engine-out attitude that lines the fuselage up with the relative wind for least drag: usually about 2 degrees of bank toward the operating engine, with the ball one-third to one-half toward it.
Airplane Flying Handbook (FAA-H-8083-3C), glossary; ch. 13
No terms match.