ATSC 231 Test 3 Questions and Answers correct

ATSC 231 Test 3 Questions and Answers correct 3 hazards of turbulence • Loss of Control • Airframe Damage • Passenger Comfort/Safety Which type of aircraft have the most accidents as a result of turbulence? Part 121 Annual turbulence injuries 58 injuries Aircraft Turbulence - Irregular motion of an aircraft in flight, especially when characterized by rapid up-and-down motion, caused by a rapid variations of atmospheric wind velocities. Turbulence Meteorology Meteorological Turbulence - Irregular fluctuations occurring in fluid motions What factors affect the transition from laminar to turbulent flow - Wind speed - Surface Roughness - Air Density - Stability - Viscosity - Other factors Two Types of turbulent flow - Wave - Eddies or Vortices Characteristics of waves - Regular oscillation of wind Characteristics of eddies - Eddies are vortices embedded in the mean wind flow What scale of turbulence affects aircraft? Microscale Critical Eddie size for aircraft 50 to 1500 ft What is the relationship between AOA and lift Lift increases until critical AOA is reached which causes a stall Load Factor - Ratio of the total air load acting on an aircraft to the gross weight of the aircraft What affects load factor in turbulence Vertical Acceleration increases it How does airspeed affect an aircrafts susceptibility to turbulence Faster you are moving the stronger the load factor Wing Loading - Ratio of weight of aircraft to wing surface area What does high wing loading lead to? More protection from turbulence magnitude of turbulence measured in what G's Gusts measured in what FPM Newton's Second Law F=ma maneuver speed speed above which it is unwise to make full application of any single flight control as it may generate a force greater than the aircraft's structural limitations Flight Load factor The highest load factor that can be expected in normal operations Design Load Factor 1.5 greater than Flight Load Factor - Protection against unexpected conditions Convective Turbulence Turbulence that results from rising currents of air Types of convection • Forced Convection - Air becomes unstable after it is forced to rise • Free Convection - Air rises because it is initially unstable 7 8 5 Convection • Dry Convection - Rising air remains unsaturated • Moist Convection - Rising air reaches saturation - Produces cloud What is a thermal rising current of warm air Characteristics of a thermal Vertical Velocity - Updraft • 200 to 2000 fpm - Downdrafts • Weaker along sides Width - Depends on Height • 100 to 300 ft at Surface • Grows to 1/4th of Height AGL What limits the height of thermals Thermal accelerates as long as Temp of parcel is warmer than Temp of environment (usually limited by temp inversion) What conditions lead to thermals Solar heating of the ground Cold air advection (cold air over warm surface) Properties of solar heating Variables Worst Case Time of Year Summer Time of Day Afternoon Terrain Low Specific Heat Wind Light What leads to deep layer of solar heating convection Warmer temperatures Properties of cold air advection Variables Worst Case Time of Year Fall & Spring Synoptic Pattern Cold Front Wind Light How to spot convective turbulence Cumulus clouds or honeycomb on satellite (open cellular convection) Cloud Streets how to minimize exposure to turbulence Fly In The Morning Climb Above Convective (or Mixed) Layer • Climb Above Mixing Level - Haze Layer In weather reports how to spot surface heating convection - Light Winds • METAR's • Surface Analysis - High Pressure In weather reports how to spot cold air advection Cold Front Depth of Convective (or Mixed) Layer - Cloud Tops STUDY THE ATMOSPHERE CHARTS that is all Neutral Stability if the lapse rate is exactly equal to the dry adiabatic rate, rising or sinking unsaturated air will cool or warm at the same rate as the air around it Absolute Stability when the environmental lapse rate is less than the wet adiabatic rate Conditional Stability when air is less than dry but more than moist lapse rate What is shear turbulence Turbulence that results from wind shear Two requirements for shear turbulence A change in wind direction and/or speed over some distance Wind shear gradient Magnitude of shear • Knots per distance (nm, ft, etc.) Critical Shear Value The amount of shear required to produce turbulence Interrelationship between wind shear and stability in producing turbulence Wind shear induces waves Breaking Wave - Occurs at critical shear value - Turbulence How does stability affect shear Stability - Suppresses Convective Mixing - Enhances Shear which means more turbulence if dam is broken probable locations of shear turbulence Surface Friction • Kelvin-Helmholtz Waves • Temperature Inversions • Fronts • Jet Streams Vertical wind profile Surface to 500 ft AGL • Speed Increases Exponentially • Direction Changes Little Above 500 ft AGL • Speed Slowly Increases Above 500 ft AGL • Direction Turns Clockwise With Height Boundary Layer layer in which friction affects wind What influences depth of boundary layer most Wind speed-strong wind is thicker boundary layer moderate or greater turbulence occurs when if Surface Winds > 30 kts How to calculate approach speed gust peak- constant wind divide by 2= a number that you add to approach speed How to spot areas of turbulence on maps High winds overly large flat areas(north dakota) High pressure gradients (isobar lines packed together) Kelvin-Helmholtz Waves Shear induced wave that develops in a concentrated layer Kelvin-Helmholtz Waves require what Strong shear and strong stability form more commonly in mountainous regions What types of temperature inversions cause turbulence • Nocturnal Radiation Inversion • Terrain Induced Inversion What leads to strong nocturnal temperature inversions? Strongest under high pressure systems • Calm or light below inversion • Stronger aloft conditions that would produce shear turbulence associated with terrain induced temperature inversions Cold Air Drainage Cold Air Drainage • Most Common at Night & Early Morning