PHAK 11: Aircraft Performance Flashcards
Introduction
What four factors affect aircraft performance?
- Aircraft weight
- Atmospheric conditions
- Runway environment
- Physical laws governing forces on an aircraft
Importance of Performance Data
Where can a pilot find operating data for an aircraft?
In the Aircraft Flight Manual/Pilot’s Operating Handbook (AFM/POH), under the performance or operational information section.
Importance of Performance Data
What types of data are included in the performance section of the AFM/POH?
Data on takeoff, climb, range, endurance, descent, and landing.
Importance of Performance Data
Why is understanding performance data essential?
For safe and efficient operation and to make practical use of the aircraft’s capabilities and limitations.
Importance of Performance Data
How is performance data commonly presented in the AFM/POH?
As tables, graphs, or both, and based on standard atmospheric conditions, pressure altitude, or density altitude.
Importance of Performance Data
What must a pilot do to use performance data effectively?
Recognize variations in presentation and make necessary adjustments based on atmospheric conditions.
Importance of Performance Data
What atmospheric factors have a major effect on aircraft performance?
Pressure and temperature.
Structure of the Atmosphere
What is the atmosphere?
An envelope of air that surrounds the Earth, composed of a mixture of gases with mass, weight, and indefinite shape.
Structure of the Atmosphere
What percentage of the atmosphere is nitrogen?
78%.
Structure of the Atmosphere
What percentage of the atmosphere is oxygen?
21%.
Structure of the Atmosphere
What percentage of the atmosphere is composed of other gases?
1% (e.g., argon, helium).
Structure of the Atmosphere
Where is most of the atmosphere’s oxygen concentrated?
Below 35,000 feet altitude.
Structure of the Atmosphere
How does air behave as a fluid?
It flows, changes shape under pressure, and expands or contracts to fill its container.
Atmospheric Pressure
What is atmospheric pressure?
The force exerted by the weight of the atmosphere in all directions.
Atmospheric Pressure
Name four flight instruments actuated by atmospheric pressure.
- Altimeter
- Airspeed Indicator (ASI)
- Vertical Speed Indicator (VSI)
- Manifold Pressure Gauge
Atmospheric Pressure
What is the average atmospheric pressure at sea level under standard conditions?
14.7 pounds per square inch (psi).
Atmospheric Pressure
How does reduced air density affect aircraft performance?
It reduces power, thrust, and lift.
Atmospheric Pressure
What are the standard atmosphere conditions at sea level?
- 59°F @ 29.92 inches of mercury (“Hg)
- 15°C @ 1013.2 millibars (mb)
Atmospheric Pressure
What is the standard temperature lapse rate?
Temperature decreases 3.5°F (2°C) per 1,000 feet up to 36,000 feet.
Atmospheric Pressure
What is the standard pressure lapse rate?
Pressure decreases 1 inch of mercury (“Hg) per 1,000 feet of altitude gain to 10,000 feet.
Atmospheric Pressure
What is the International Standard Atmosphere (ISA)?
A worldwide standard established by the International Civil Aviation Organization (ICAO) with specific lapse rates for temperature and pressure.
Atmospheric Pressure
What are nonstandard temperature and pressure?
Conditions where atmospheric temperature or pressure differ from the standard lapse rates.
Atmospheric Pressure
Why are corrections needed for nonstandard atmospheric conditions?
Because aircraft instruments and performance are calibrated for standard atmospheric conditions.
Pressure Altitude
What is pressure altitude?
The height above the standard datum plane (SDP), where atmospheric pressure is 29.92 “Hg.
Pressure Altitude
What does the altimeter measure when set to 29.92 “Hg?
Pressure altitude.
Pressure Altitude
What is the standard datum plane (SDP)?
A theoretical level where atmospheric pressure is 29.92 “Hg and the weight of air is 14.7 psi.
Pressure Altitude
Why is pressure altitude important?
It is used to determine aircraft performance and assign flight levels above 18,000 feet.
Pressure Altitude
What are three methods to determine pressure altitude?
- Set the altimeter barometric scale to 29.92 “Hg and read the indicated altitude.
- Apply a correction factor to the indicated altitude based on the reported altimeter setting.
- Use a flight computer.
Density Altitude
What is density altitude?
The altitude in the standard atmosphere corresponding to a specific air density.
Density Altitude
How is density altitude calculated?
By correcting pressure altitude for nonstandard temperature.
Density Altitude
How does air density affect aircraft performance?
- Increased air density (lower density altitude): Increases aircraft performance.
- Decreased air density (higher density altitude): Decreases aircraft performance.
Density Altitude
What five conditions result in high density altitude?
- High elevations.
- Low atmospheric pressure.
- High temperatures.
- High humidity.
- Combination of the above factors.
Density Altitude
What four conditions result in low density altitude?
- Low elevations.
- High atmospheric pressure.
- Low temperatures.
- Low humidity.
Density Altitude
Why is density altitude important for aircraft performance?
Aircraft perform as though operating at the altitude equal to the existing density altitude, which affects engine power, lift, and takeoff/landing distances.
Density Altitude
What three tools can be used to determine density altitude?
- Flight computer.
- Temperature correction tables.
- Graphs or charts.
Density Altitude: Effects of Pressure on Density
What happens to air density when pressure increases?
Air density increases.
Density Altitude: Effects of Pressure on Density
What happens to air density when pressure decreases?
Air density decreases.
Density Altitude: Effects of Pressure on Density
How are air density and pressure related?
Air density is directly proportional to pressure, assuming constant temperature.
Density Altitude: Effects of Pressure on Density
If air pressure is doubled, what happens to air density?
Air density is also doubled.
Density Altitude: Effects of Pressure on Density
What must remain constant for air density to be proportional to pressure?
Temperature.
Density Altitude: Effects of Temperature on Density
What happens to air density as temperature increases?
Air density decreases.
Density Altitude: Effects of Temperature on Density
What happens to air density as temperature decreases?
Air density increases.
Density Altitude: Effects of Temperature on Density
How are air density and temperature related?
Air density varies inversely with temperature, assuming constant pressure.
Density Altitude: Effects of Temperature on Density
In the atmosphere, which has the dominant effect on air density: temperature or pressure changes with altitude?
The rapid drop in pressure with altitude usually dominates, causing air density to decrease with altitude.
Density Altitude: Effects of Humidity (Moisture) on Density
How does humidity affect air density?
As humidity increases, air density decreases.
Density Altitude: Effects of Humidity (Moisture) on Density
What happens to density altitude as humidity increases?
Density altitude increases.
Density Altitude: Effects of Humidity (Moisture) on Density
Why is moist air lighter than dry air?
Water vapor is lighter than air, making moist air less dense.
Density Altitude: Effects of Humidity (Moisture) on Density
What is relative humidity?
The percentage of water vapor in the air compared to the maximum it can hold at a given temperature.
Density Altitude: Effects of Humidity (Moisture) on Density
How does temperature affect the amount of water vapor air can hold?
Warm air can hold more water vapor, while cold air can hold less.
Density Altitude: Effects of Humidity (Moisture) on Density
What is the relative humidity of perfectly dry air?
0%.
Density Altitude: Effects of Humidity (Moisture) on Density
What is the relative humidity of saturated air?
100%.
Density Altitude: Effects of Humidity (Moisture) on Density
What are three factors that influence aircraft performance through their effect on air density?
- Pressure
- Temperature
- Humidity
Density Altitude: Effects of Humidity (Moisture) on Density
What should pilots expect in high humidity conditions?
A decrease in overall aircraft performance.
Performance
What does “performance” describe in aviation?
The ability of an aircraft to accomplish specific tasks that make it useful for certain purposes.
Performance
Name five primary factors affected by aircraft performance.
- Takeoff and landing distance
- Rate of climb
- Ceiling
- Payload
- Range
Performance
What are three additional factors influenced by aircraft performance?
- Speed
- Maneuverability
- Stability
Performance
What is an example of opposing performance factors?
High speed versus short landing distance.
Performance
What dictates differences in aircraft design and specialization?
The prioritization of certain performance factors, such as payload or range.
Performance
What defines the power and thrust requirements of an aircraft?
The aerodynamic characteristics of the aircraft.
Performance
What defines the power and thrust available to an aircraft?
The powerplant characteristics.
Performance
What is the purpose of matching aerodynamic configuration with powerplant characteristics?
To provide maximum performance for specific design conditions (e.g., range, endurance, climb).
Performance: Straight-and-Level Flight
What is required for an aircraft to remain in steady, level flight?
- Lift must equal weight.
- Thrust must equal drag.
Performance: Straight-and-Level Flight
What defines the thrust required to maintain steady, level flight?
Aircraft drag.
Performance: Straight-and-Level Flight
What are the two types of drag that affect steady, level flight?
- Induced drag
- Parasite drag
Performance: Straight-and-Level Flight
Which type of drag predominates at high speed?
Parasite drag.
Performance: Straight-and-Level Flight
Which type of drag predominates at low speed?
Induced drag.
Performance: Straight-and-Level Flight
How does parasite drag change when airspeed doubles?
Parasite drag becomes four times greater.
Performance: Straight-and-Level Flight
How does induced drag change when airspeed doubles?
Induced drag is reduced to one-fourth of the original value.
Performance: Straight-and-Level Flight
How does power required to overcome parasite drag change when airspeed doubles?
It becomes eight times the original value.
Performance: Straight-and-Level Flight
How does power required to overcome induced drag change when airspeed doubles?
It is reduced to one-half the original value.
Performance: Straight-and-Level Flight
When is the maximum level flight speed achieved?
When the thrust or power required equals the maximum thrust or power available.
Performance: Straight-and-Level Flight
What typically limits the minimum level flight airspeed?
Stall, stability, or control issues.
Performance: Climb Performance
What are the two forms of mechanical energy for aircraft?
- Kinetic Energy (KE): energy of speed
- Potential Energy (PE): energy of position
Performance: Climb Performance
What does Kinetic Energy (KE) depend on?
KE = ½ × m × v²
- m = object mass
- v = object velocity (airspeed)
Performance: Climb Performance
What does Potential Energy (PE) depend on?
PE = m × g × h
- m = object mass
- g = gravity field strength
- h = object height (altitude)
Performance: Climb Performance
Define “Thrust.”
Thrust is a force or pressure exerted on an object, measured in pounds (lb) or newtons (N).
Performance: Climb Performance
Define “Power.”
Power is the rate of performing work or transferring energy, measured in horsepower (hp) or kilowatts (kW).
Performance: Climb Performance
What are the two basic factors contributing to positive climb performance?
Using excess power above what is required for level flight.
Converting airspeed (KE) into altitude (PE).
Performance: Climb Performance
What is “Maximum Angle of Climb (AOC)” and its corresponding speed?
The climb performance to clear obstacles, achieved at VX.
Performance: Climb Performance
What is “Maximum Rate of Climb (ROC)” and its corresponding speed?
The climb performance for the greatest altitude gain over time, achieved at VY.
Performance: Climb Performance
When might Maximum ROC (VY) not be sufficient?
In situations requiring clearance of obstacles.
Performance: Climb Performance
What is a “Zoom Climb”?
A climb where airspeed (KE) is converted into altitude (PE), resulting in decreased airspeed.
Performance: Climb Performance
Why is climb performance evaluated? (2)
- To avoid obstacles.
- To reach higher altitudes for better weather, fuel economy, and other benefits.
Performance: Climb Performance, Angle of Climb (AOC)
What is Angle of Climb (AOC)?
AOC is a comparison of altitude gained relative to distance traveled, defined by the inclination of the flight path.
Performance: Climb Performance, Angle of Climb (AOC)
At what speed does maximum AOC occur?
At VX, the speed for maximum altitude increase with minimum horizontal distance.
Performance: Climb Performance, Angle of Climb (AOC)
When is maximum AOC performance useful?
When taking off from a short airfield surrounded by high obstacles, such as trees or power lines.
Performance: Climb Performance, Angle of Climb (AOC)
How is maximum AOC achieved?
By having excess thrust available to push the aircraft upward more steeply.
Performance: Climb Performance, Angle of Climb (AOC)
Where does maximum excess thrust for maximum AOC occur in a jet airplane?
At the airspeed where thrust required is at a minimum, approximately L/DMAX.
Performance: Climb Performance, Angle of Climb (AOC)
Where does maximum excess thrust for maximum AOC occur in a propeller airplane?
At an airspeed below L/DMAX, frequently just above stall speed.
Performance: Climb Performance, Rate of Climb (ROC)
What is Rate of Climb (ROC)?
ROC is the altitude gained relative to the time needed to reach that altitude.
Performance: Climb Performance, Rate of Climb (ROC)
At what speed does maximum ROC occur?
At VY, the speed for the greatest vertical distance over a given period of time.
Performance: Climb Performance, Rate of Climb (ROC)
When is maximum ROC performance useful?
When expediting a climb to an assigned altitude.
Performance: Climb Performance, Rate of Climb (ROC)
What is the key difference between maximum ROC and maximum AOC?
Maximum ROC achieves the greatest altitude gain over time, while maximum AOC achieves the greatest altitude gain over the least horizontal distance.
Performance: Climb Performance, Rate of Climb (ROC)
What does ROC performance depend on?
Excess power available beyond what is needed to maintain level flight.
Performance: Climb Performance, Rate of Climb (ROC)
Where does maximum ROC occur in a jet airplane?
At an airspeed greater than L/DMAX and an AOA less than L/DMAX AOA.
Performance: Climb Performance, Rate of Climb (ROC)
Where does maximum ROC occur in a propeller airplane?
At an airspeed and AOA combination closer to L/DMAX.
Performance: Climb Performance, Climb Performance Factors
What factors directly affect climb performance?
Weight, altitude, and configuration changes (e.g., landing gear and flaps).
Performance: Climb Performance, Climb Performance Factors
How does increased weight affect climb performance? (3)
- Increases induced and parasite drag.
- Reduces reserve thrust and power.
- Decreases maximum ROC and AOC performance.
Performance: Climb Performance, Climb Performance Factors
How does altitude affect climb performance? (3)
- Increases power required.
- Decreases power available.
- Diminishes climb performance with altitude.
Performance: Climb Performance, Climb Performance Factors
What is the absolute ceiling of an aircraft?
The altitude where ROC is zero, and only one airspeed allows steady, level flight.
Performance: Climb Performance, Climb Performance Factors
What is the service ceiling of an aircraft?
The altitude at which the aircraft cannot climb at more than 100 feet per minute (fpm).
Performance: Climb Performance, Climb Performance Factors
Define power loading.
The total weight of the aircraft divided by the rated horsepower of the engine, expressed in pounds per horsepower.
Performance: Climb Performance, Climb Performance Factors
Define wing loading.
The total weight of the airplane divided by the wing area (including ailerons), expressed in pounds per square foot.
Performance: Climb Performance, Climb Performance Factors
Define blade loading.
The total weight of a helicopter divided by the area of the rotor blades, expressed in pounds per square foot.
Performance: Climb Performance, Climb Performance Factors
Define disk loading.
The total weight of a helicopter divided by the area of the disk swept by the rotor blades.
Performance: Range Performance
What are the two main goals of range performance?
- Extract maximum flying distance from a given fuel load.
- Fly a specific distance with minimum fuel expenditure.
Performance: Range Performance
How is specific range defined?
- Nautical miles (NM) per pound of fuel.
- NM per hour divided by pounds of fuel per hour.
- Knots divided by fuel flow.
Performance: Range Performance
How is specific endurance defined?
- Flight hours per pound of fuel.
- Flight hours per hour divided by pounds of fuel per hour.
- 1 divided by fuel flow.
Performance: Range Performance
What three variables affect specific range?
- Aircraft gross weight.
- Altitude.
- External aerodynamic configuration.
Performance: Range Performance
What flight condition maximizes specific range?
Flying at maximum speed per unit of fuel flow.
Performance: Range Performance
What is L/DMAX, and why is it significant for range?
L/DMAX is the point of maximum lift-to-drag ratio.
It represents the airspeed and AOA for the most efficient range.
Performance: Range Performance
What happens to specific range when aircraft gross weight decreases?
Specific range increases as gross weight decreases due to reduced power required.
Performance: Range Performance
How does altitude affect range performance in propeller-driven aircraft? (3)
- Higher altitude increases TAS and power required.
- Drag remains constant, but greater TAS increases proportional power required.
- Specific range is largely unaffected unless fuel consumption or propeller efficiency changes.
Performance: Range Performance
What is the advantage of supercharging for range performance?
Maintains cruise power at high altitude, increasing TAS and range.
Performance: Range Performance
Why might long-range cruise operations not use peak specific range?
Operating at 99% of maximum specific range trades 1% of range for 3-5% higher cruise speed, which has operational benefits.
Performance: Range Performance
What must a pilot do to optimize range in long-range aircraft? (2)
- Adjust airspeed, power settings, and altitude as fuel weight decreases.
- Monitor variations in speed and power to maintain L/DMAX conditions.
Performance: Range Performance
How does high humidity affect range performance?
High humidity decreases air density, increases density altitude, and reduces overall range performance.
Performance: Region of Reversed Command
What determines the power required and power available in flight?
- Aerodynamic properties determine power required.
- Powerplant capabilities determine power available.
Performance: Region of Reversed Command
What condition must prevail in steady, level flight?
- Lift equals weight.
- Thrust equals drag (set by the powerplant).
Performance: Region of Reversed Command
What does the power required curve show?
At low airspeeds near stall or minimum controllable airspeed, the power required for steady, level flight is high.
Performance: Region of Reversed Command
What is flight in the region of normal command? (3)
- Higher airspeed = higher power setting.
- Lower airspeed = lower power setting.
- Applies to most flying conditions (climb, cruise, maneuvers).
Performance: Region of Reversed Command
What is flight in the region of reversed command? (3)
- Higher airspeed = lower power setting.
- Lower airspeed = higher power setting.
- Occurs at low speeds, below the speed for maximum endurance.
Performance: Region of Reversed Command
Why is it called the region of reversed command?
Increased power is required with decreased airspeed, contrary to normal command.
Performance: Region of Reversed Command
What speed range defines the region of reversed command?
Between the speed for minimum required power and stall speed (or minimum controllable speed).
Performance: Region of Reversed Command
What is the best endurance airspeed?
The airspeed at the lowest point on the power required curve, requiring the least brake horsepower to sustain level flight.
Performance: Region of Reversed Command
Provide two examples of operating in the region of reversed command.
- Low airspeed, high pitch attitude power approach for a short-field landing.
- Soft-field takeoff and climb without reaching normal climb pitch attitude and airspeed.
Performance: Region of Reversed Command
What can happen during a short-field landing if a high sink rate develops? (2)
- Power may reduce or stop the descent.
- Without power, the aircraft may stall or be unable to flare.
Performance: Region of Reversed Command
What must a pilot do if entering the region of reversed command during a soft-field takeoff?
Lower pitch attitude to increase airspeed, even if it results in altitude loss.
Performance: Region of Reversed Command
What is critical when operating in the region of reversed command?
Precise control of airspeed.
Takeoff and Landing Performance
When do the majority of pilot-caused aircraft accidents occur?
During takeoff and landing phases of flight.
Takeoff and Landing Performance
What type of motion characterizes takeoff and landing performance? (2)
- Takeoff: Accelerated motion (from zero speed to takeoff speed).
- Landing: Decelerated motion (from landing speed to zero speed).
Takeoff and Landing Performance
What are three important factors in takeoff and landing performance?
- Takeoff or landing speed (function of stall or minimum flying speed).
- Rate of acceleration/deceleration during the roll.
- Takeoff or landing roll distance (dependent on acceleration/deceleration and speed).
Takeoff and Landing Performance
How does speed affect the energy of an airplane during motion?
- Energy varies with the square of the speed.
- Example: An airplane at 75 knots has four times the energy of one at 37 knots
Takeoff and Landing Performance
How does speed affect stopping distance?
An airplane requires four times the distance to stop at double the speed.
Takeoff and Landing Performance: Runway Surface and Gradient
What assumptions are typically made for runway conditions in performance charts?
Runway is paved, level, smooth, and dry.
Takeoff and Landing Performance: Runway Surface and Gradient
Name five types of runway surfaces.
- Concrete
- Asphalt
- Gravel
- Dirt
- Grass
Takeoff and Landing Performance: Runway Surface and Gradient
Where can the surface type of a specific runway be found?
In the Chart Supplement U.S.
(formerly Airport/Facility Directory)
Takeoff and Landing Performance: Runway Surface and Gradient
What effect do soft, grassy, or muddy runways have on takeoff? (2)
- Increase ground roll distance.
- Tires may sink, reducing smooth rolling.
Takeoff and Landing Performance: Runway Surface and Gradient
How do wet or muddy surfaces affect landing performance? (2)
- Reduce friction, which can decrease braking effectiveness.
- Act as obstructions, reducing landing distance.
Takeoff and Landing Performance: Runway Surface and Gradient
What is braking effectiveness?
The amount of power applied to brakes without skidding the tires.
Takeoff and Landing Performance: Runway Surface and Gradient
What is runway gradient or slope, and how is it expressed? (2)
- Change in runway height over its length.
- Expressed as a percentage (e.g., 3% gradient = 3 feet height change per 100 feet length).
Takeoff and Landing Performance: Runway Surface and Gradient
How does an upsloping runway affect takeoff and landing? (2)
- Takeoff: Impedes acceleration, increases ground run.
- Landing: Reduces landing roll.
Takeoff and Landing Performance: Runway Surface and Gradient
How does a downsloping runway affect takeoff and landing? (2)
- Takeoff: Aids acceleration, shortens ground run.
- Landing: Increases landing roll.
Takeoff and Landing Performance: Runway Surface and Gradient
Where is runway slope information located?
In the Chart Supplement U.S.
(formerly Airport/Facility Directory)
T. and L. Performance: Water on the Runway and Dynamic Hydroplaning
What happens to braking effectiveness when water is on the runway? (2)
- Friction is reduced.
- Braking effectiveness can be completely lost due to hydroplaning.
T. and L. Performance: Water on the Runway and Dynamic Hydroplaning
What is dynamic hydroplaning? (2)
A condition where tires ride on a thin sheet of water, causing:
- Loss of braking.
- Loss of directional control.
T. and L. Performance: Water on the Runway and Dynamic Hydroplaning
What feature on some runways helps minimize hydroplaning?
Grooves to drain off water.
T. and L. Performance: Water on the Runway and Dynamic Hydroplaning
How can the minimum speed for dynamic hydroplaning be calculated?
- Formula: Multiply the square root of main gear tire pressure (psi) by 9.
- Example: 36 psi tire pressure = Hydroplaning begins at 54 knots.
T. and L. Performance: Water on the Runway and Dynamic Hydroplaning
What factors increase the risk of hydroplaning? (2)
- Landing at higher-than-recommended touchdown speeds.
- Wet runway conditions.
T. and L. Performance: Water on the Runway and Dynamic Hydroplaning
Can hydroplaning occur below the initial hydroplaning speed?
Yes, once hydroplaning starts, it can continue below the initial hydroplaning speed.
T. and L. Performance: Water on the Runway and Dynamic Hydroplaning
How can directional control be maximized on a wet runway? (3)
- Land into the wind.
- Avoid abrupt control inputs.
- Use aerodynamic braking to its fullest.
T. and L. Performance: Water on the Runway and Dynamic Hydroplaning
What precautions should be taken when landing on a wet runway? (3)
- Anticipate braking problems before landing.
- Be prepared for hydroplaning.
- Choose a runway aligned with the wind.
Takeoff and Landing Performance: Takeoff Performance
Why is the minimum takeoff distance important?
It defines runway requirements for safe operations.
Takeoff and Landing Performance: Takeoff Performance
What is the lift-off speed relative to stall or minimum control speed?
1.05 to 1.25 times the stall speed or minimum control speed.
Takeoff and Landing Performance: Takeoff Performance
What forces affect takeoff acceleration? (2)
- Powerplant thrust (main force).
- Lift and drag (affected by AOA and dynamic pressure).
Takeoff and Landing Performance: Takeoff Performance
What does EPR measure in a turbojet or turbofan engine?
The ratio between exhaust pressure and inlet pressure, indicating engine thrust.
Takeoff and Landing Performance: Takeoff Performance
Name three effects of increased gross weight on takeoff performance.
- Higher lift-off speed.
- Greater mass to accelerate.
- Increased retarding forces (drag and ground friction).
Takeoff and Landing Performance: Takeoff Performance
What are three effects of a 10% increase in takeoff gross weight?
- 5% increase in takeoff velocity.
- At least 9% decrease in acceleration rate.
- At least 21% increase in takeoff distance.
Takeoff and Landing Performance: Takeoff Performance
How does wind affect takeoff distance?
- Headwind reduces takeoff distance:
- 10% of takeoff airspeed = ~19% reduction in distance.
- Tailwind increases takeoff distance:
- 10% of takeoff airspeed = ~21% increase in distance.
Takeoff and Landing Performance: Takeoff Performance
What happens if takeoff speed is below the recommended value?
Aircraft may stall, be difficult to control, or have poor ROC.
Takeoff and Landing Performance: Takeoff Performance
What happens if takeoff speed exceeds the recommended value by 10%?
Takeoff distance increases by 21%.
Takeoff and Landing Performance: Takeoff Performance
How does density altitude affect takeoff performance? (2)
- Greater takeoff speed is required.
- Thrust decreases, reducing net accelerating force.
Takeoff and Landing Performance: Takeoff Performance
How does altitude affect different engine types? (2)
- Unsurpercharged engines: Power output decreases immediately.
- Supercharged engines: No power loss until above critical altitude.
Takeoff and Landing Performance: Takeoff Performance
What are the four most critical conditions affecting takeoff performance?
- High gross weight.
- High altitude.
- High temperature.
- Unfavorable wind.
Takeoff and Landing Performance: Takeoff Performance
What four factors must be considered in takeoff distance predictions?
- Pressure altitude and temperature (density altitude effect).
- Gross weight.
- Wind direction and speed.
- Runway slope and condition.
Takeoff and Landing Performance: Landing Performance
Why is landing distance critical?
It defines runway requirements for safe landing operations.
Takeoff and Landing Performance: Landing Performance
What is the relationship between landing speed and stall speed?
Landing speed is a fixed percentage of stall speed or minimum control speed, typically allowing a safe margin above stall.
Takeoff and Landing Performance: Landing Performance
What is required to achieve minimum landing distance? (2)
- Landing at the specified speed.
- Maximum deceleration during the landing roll (e.g., effective braking).
Takeoff and Landing Performance: Landing Performance
When is aerodynamic drag most effective during landing?
At speeds above 60–70% of touchdown speed. Below this, braking must be used for deceleration.
Takeoff and Landing Performance: Landing Performance
How does increased gross weight affect landing performance? (2)
- Higher landing speed is required.
- Increased landing distance (proportional to weight).
- Example: 10% weight increase = 10% distance increase.
Takeoff and Landing Performance: Landing Performance
How does wind affect landing distance? (2)
- Headwind reduces landing distance by lowering groundspeed at touchdown.
- Example: 10-knot headwind = ~19% reduction.
- Tailwind increases landing distance by requiring a higher groundspeed.
- Example: 10-knot tailwind = ~21% increase.
Takeoff and Landing Performance: Landing Performance
How does density altitude affect landing performance? (2)
- TAS increases, but IAS remains the same.
- Landing distance increases due to higher TAS.
- Example: Landing at 5,000 ft = 16% longer than at sea level.
Takeoff and Landing Performance: Landing Performance
What happens if landing speed exceeds the recommended value by 10%? (2)
- Landing distance increases by ~21%.
- Brakes must dissipate more kinetic energy, increasing wear and risk of tire blowouts.
Takeoff and Landing Performance: Landing Performance
What are the three most critical landing conditions?
- High gross weight.
- High density altitude.
- Unfavorable wind (e.g., tailwind).
Takeoff and Landing Performance: Landing Performance
How do poor decisions during landing impact performance?
- Errors compound, making corrections difficult or impossible.
- Example: Excess speed, tailwind, and hydroplaning increase landing distance significantly.
Takeoff and Landing Performance: Landing Performance
What are the four primary considerations for landing distance predictions from AFM/POH data?
- Pressure altitude and temperature (density altitude effect).
- Gross weight (affects landing speed and distance).
- Wind (headwind reduces, tailwind increases distance).
- Runway slope and condition (e.g., snow, ice, soft ground)
Takeoff and Landing Performance: Landing Performance
At what speed does hydroplaning occur for a tire pressure of 36 psi?
54 knots (√36 × 9).
Takeoff and Landing Performance: Landing Performance
Why is hydroplaning dangerous during landing? (2)
- Braking is ineffective until speed decreases below hydroplaning threshold.
- Increases landing distance significantly.
Takeoff and Landing Performance: Landing Performance
What is a common pilot error during hydroplaning?
Locking the brakes, which exacerbates hydroplaning and reduces deceleration.
Takeoff and Landing Performance: Landing Performance
What is the effect of combining multiple bad decisions during landing?
- Synergistic effect, making corrections increasingly difficult.
- Example: High airspeed, tailwind, and poor braking can lead to runway overrun.
Performance Charts
What do performance charts allow a pilot to predict? (4)
- Takeoff performance.
- Climb performance.
- Cruise performance.
- Landing performance.
Performance Charts
Where are performance charts found?
In the AFM/POH provided by the aircraft manufacturer.
Performance Charts
Under what four conditions are performance charts created?
- Test flights conducted in a new aircraft.
- Normal operating conditions.
- Average piloting skills.
- Aircraft and engine in good working order.
Performance Charts
Why might performance chart data be inaccurate in real-world scenarios? (3)
- Aircraft is not in good working order.
- Operating under adverse conditions.
- Piloting skills are below average.
Performance Charts
Why should performance be computed before every flight?
Every flight is different, and each aircraft has unique performance numbers.
Performance Charts
What should be done before using a performance chart? (3)
- Read the manufacturer’s instructions.
- Understand how to adapt the chart for flight conditions.
- Refer to the example provided for that specific chart.
Performance Charts
How are performance chart formats typically presented? (3)
- Table format.
- Graph format.
- Combined graphs for multiple conditions (e.g., density altitude, weight, wind)
Performance Charts
What is the advantage of combined graphs in performance charts?
They allow pilots to predict performance under multiple conditions on one chart.
Performance Charts
Why is accuracy important when using performance charts?
A small error in reading the chart can lead to large errors in flight planning.
Performance Charts
What two methods can be used to extract information from performance charts?
- Direct reading.
- Interpolation.
Performance Charts
What types of performance are typically covered by performance charts? (3)
- Takeoff and landing distance.
- Climb rates.
- Cruise fuel consumption and time en route.
Performance Charts: Interpolation
What is interpolation in the context of performance charts?
The process of computing intermediate values using known data from the chart.
Performance Charts: Interpolation
Why is interpolation necessary for some performance charts?
Not all specific flight conditions are directly listed on the chart.
Performance Charts: Interpolation
What is a safety practice when interpolating values from charts?
Round off values to reflect slightly more adverse conditions, providing a safety margin.
Performance Charts: Interpolation
What is an example of where interpolation might be used?
Calculating takeoff distance for conditions not directly listed on the chart.
Performance Charts: Interpolation
How does rounding off interpolated values benefit flight planning?
It ensures a more conservative estimate, enhancing safety.
