PPL Flight Performance and Planning flashcards
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32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Density altitude
- Pressure altitude corrected for non-standard temperature; it represents the altitude at which the aircraft would perform in ISA conditions and drives takeoff, climb, and landing performance.
- Pressure altitude
- The altitude indicated when the altimeter subscale is set to 1013.25 hPa (29.92 inHg); it is the reference used for performance charts and flight levels.
- True altitude
- Actual height above mean sea level; differs from indicated altitude because of pressure and temperature errors, being lower than indicated in cold air.
- QNH
- The altimeter setting that, when set on the subscale, makes the altimeter indicate elevation above mean sea level at the aerodrome reference point.
- QFE
- The altimeter setting that makes the altimeter read zero at the aerodrome reference point, giving height above that point rather than altitude above sea level.
- ISA temperature lapse
- Standard atmosphere temperature is 15 degrees Celsius at sea level, decreasing 1.98 degrees Celsius per 1000 feet up to the tropopause at 36,090 feet.
- Headwind component
- The component of wind along the runway axis, calculated as wind speed multiplied by the cosine of the angle between wind direction and runway heading.
- Crosswind component
- The wind component perpendicular to the runway, calculated as wind speed multiplied by the sine of the angle between wind direction and runway heading.
- Maximum demonstrated crosswind
- A crosswind value shown in the AFM/POH that was demonstrated during certification; it is not a limiting value but a reference for pilot capability.
- V1
- The decision speed at which, following an engine failure, the takeoff can either be continued safely or rejected within the remaining runway.
- VR
- Rotation speed, at which the pilot applies back pressure to raise the nose and achieve the attitude for liftoff.
- V2
- Takeoff safety speed, the speed to be maintained after liftoff with one engine inoperative to guarantee the required climb gradient.
- Vref
- Landing reference speed, normally 1.3 times the stall speed in the landing configuration at maximum landing weight.
- Vx
- The speed for best angle of climb, giving the greatest height gain for a given horizontal distance; used to clear obstacles.
- Vy
- The speed for best rate of climb, giving the greatest height gain per unit time; used for the fastest altitude gain.
- Service ceiling
- The altitude at which the maximum rate of climb has decreased to 100 feet per minute under ISA conditions at maximum weight.
- Absolute ceiling
- The altitude at which the maximum rate of climb becomes zero, so the aircraft cannot climb higher in those conditions.
- Load factor
- The ratio of lift to weight; in a level turn it equals 1 divided by the cosine of the bank angle, reaching 2 at 60 degrees bank.
- Stall speed and weight
- Stall speed varies with the square root of the weight ratio, so a 21 percent weight increase raises the stall speed by about 10 percent.
- Moment
- The product of a weight and its arm from the datum; summing moments and dividing by total weight gives the centre of gravity position.
- Centre of gravity
- The point at which the aircraft's total weight is considered to act; it must remain between the forward and aft limits throughout the flight.
- Datum
- An arbitrary reference plane from which all arms are measured when computing weight and balance; it may lie ahead of, behind, or within the aircraft.
- Basic empty weight
- The weight of the aircraft including structure, powerplant, equipment, unusable fuel, and full operating fluids, excluding payload and usable fuel.
- Maximum zero fuel weight
- A structural limit equal to the maximum weight of the aircraft without usable fuel; fuel added beyond this point must be carried within the design limit.
- Useful load
- The difference between maximum takeoff weight and basic empty weight; it covers crew, passengers, baggage, and usable fuel.
- Forward CG effects
- A forward centre of gravity increases stall speed and landing distance, raises elevator forces, and can reduce climb performance and range.
- Aft CG effects
- An aft centre of gravity reduces longitudinal stability, lightens control forces, may increase cruise speed, and can make stall and spin recovery difficult.
- Final reserve fuel
- The fuel required to hold for a specified period, commonly 30 minutes for VFR and 45 minutes for IFR, calculated at holding fuel flow.
- Specific range
- The distance flown per unit of fuel consumed, obtained by dividing true airspeed by fuel flow; used to compare cruise efficiency.
- Endurance
- The maximum time an aircraft can remain airborne, calculated by dividing usable fuel by the fuel flow at the selected power setting.
- Best glide speed
- The speed giving the greatest glide distance, corresponding to the best lift-to-drag ratio; a headwind raises it and a tailwind lowers it.
- Runway slope effect
- Uphill slope increases takeoff distance by roughly 5 percent per 1 percent gradient, while downhill slope increases landing distance by about 10 percent per 1 percent.