Reference
Aviation glossary
Concise definitions for aviation terminology — from METAR and NOTAM to aerodynamics and airline operations. Search directly or scan alphabetically.
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Safety FactorA multiplier applied to a structure's expected limit load to ensure it can survive forces beyond normal operating conditions. FAA regulations require a minimum safety factor of 1.5 for transport-category aircraft. Secondary ScreeningSecondary screening is an additional security check triggered when primary screening detects a potential concern. It may include pat-downs, manual baggage inspections, explosive trace detection, or repeat imaging to resolve the alert. Secure Flight ProgramThe Secure Flight Program is a TSA system that vets passenger information against federal watch lists before flight departure, determining whether travelers can board normally, receive enhanced screening, or are prohibited from flying. SIGMETA SIGMET (Significant Meteorological Information) is an urgent weather advisory issued to pilots warning of hazardous en route conditions capable of affecting aircraft safety. SIGWX ChartA SIGWX chart is a graphical weather forecast highlighting aviation hazards such as turbulence, icing, thunderstorms, and low visibility across specific altitude bands. It uses standard ICAO symbols to help pilots and dispatchers identify... SlipA slip is a flight maneuver where the aircraft's nose points in a different direction than its actual path through the air, creating increased drag to descend more steeply without gaining airspeed. Slip (Aerodynamic)A slip is a flight maneuver in which the aircraft's nose points in a different direction than its flight path, increasing drag to steepen descent without adding airspeed. Sortation SystemAn automated network of conveyors, scanners, and diverters that reads baggage destination data and routes items to correct outbound locations without manual intervention. SPECIA SPECI is an unscheduled weather report issued by an airport when meteorological conditions change significantly between routine hourly METAR reports, ensuring pilots receive current information for decision-making. SpinA spin is an aggravated stall where one wing stalls more deeply than the other, causing the aircraft to autorotate around a near-vertical axis while descending steeply. Recovery requires specific control inputs following the PARE sequence. StabilityAn aircraft's tendency to return to its original flight attitude after a disturbance without pilot input. Stability is measured in static (initial reaction) and dynamic (sustained behavior) terms across three axes: pitch, roll, and yaw. Stall SpeedThe minimum airspeed at which a wing generates enough lift to sustain level flight. Below this speed, the wing exceeds its critical angle of attack and lift collapses. Stall Warning SystemA stall warning system is an onboard safety device that alerts pilots when the aircraft approaches a stall by monitoring the wing's angle of attack. It supplements pilot awareness through aural warnings, cockpit lights, stick shakers, or... Station IdentifierA four-letter ICAO code that uniquely identifies an airport or weather station in aviation weather reports like METARs and TAFs, with the first letter indicating geographic region. Stationary FrontA stationary front is a weather boundary between two air masses that remains locked in place for hours or days because neither air mass has sufficient pressure gradient to advance. It produces persistent low ceilings, reduced visibility, and... Statute MileA statute mile is a unit of distance equal to 5,280 feet (1,609 meters). In U.S. aviation, it is used primarily in visibility reports and weather observations. Stress ConcentrationStress concentration is a localized spike in internal stress that occurs when a structural component has a geometric irregularity like a hole, notch, or sharp corner that disrupts smooth stress flow. Structural icingStructural icing is the accumulation of ice on an aircraft's airframe, wings, and control surfaces when supercooled water droplets freeze on contact with the aircraft during flight. Supercooled water dropletsLiquid water droplets that remain unfrozen at temperatures below 0°C and freeze instantly on contact with aircraft surfaces, causing structural icing. Surface Analysis ChartA weather map depicting current atmospheric conditions at ground level, including pressure systems, frontal boundaries, and isobars. Pilots use surface analysis charts to assess active weather patterns during flight planning.
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