Density & Performance Quiz PPL
What effect does high density altitude, as compared to low density altitude, have on propeller efficiency and why?
Efficiency is increased due to less friction on the propeller blades.
Efficiency is reduced because the propeller exerts less force at high density altitudes than at low density altitudes.
Efficiency is reduced due to the increased force of the propeller in the thinner air.
What is density altitude?
The height above the standard datum plane.
The pressure altitude corrected for non-standard temperature.
The altitude read directly from the altimeter.
If the outside air temperature (OAT) at a given altitude is warmer than standard, the density altitude is
equal to pressure altitude.
lower than pressure altitude.
higher than pressure altitude.
Which combination of atmospheric conditions will reduce aircraft takeoff and climb performance?
Low temperature, low relative humidity, and low density altitude.
High temperature, low relative humidity, and low density altitude.
High temperature, high relative humidity, and high density altitude.
What effect does high density altitude have on aircraft performance?
It increases engine performance.
It reduces climb performance.
It increases takeoff performance.
What effect, if any, does high humidity have on aircraft performance?
It increases performance.
It decreases performance.
It has no effect on performance.
Under which condition will pressure altitude be equal to true altitude?
When the atmospheric pressure is 29.92 inches Hg.
When standard atmospheric conditions exist.
When indicated altitude is equal to the pressure altitude.
Under what condition is pressure altitude and density altitude the same value?
At sea level, when the temperature is 0 °F.
When the altimeter has no installation error.
At standard temperature.
Which factor would tend to increase the density altitude at a given airport?
An increase in barometric pressure.
An increase in ambient temperature.
A decrease in relative humidity.
A pilot and two passengers landed on a 2,100 foot east-west gravel strip with an elevation of 1,800 feet. The temperature is warmer than expected and after computing the density altitude it is determined the takeoff distance over a 50 foot obstacle is 1,980 feet. The airplane is 75 pounds under gross weight. What would be the best choice?
Takeoff to the west because the headwind will give the extra climb-out time needed.
Try a takeoff without the passengers to make sure the climb is adequate.
Wait until the temperature decreases, and recalculate the takeoff performance.
It's a warm summer day and you are planning a flight through a mountain pass at 11,500 feet MSL. Your aircraft’s service ceiling is 14,000 feet. You have calculated the density altitude through the mountain pass will be 14,800 feet. An appropriate course of action would be?
Density altitude only matters for takeoff and landing. Proceed as planned.
Change your flight plan route so that you do not exceed the service ceiling of the aircraft.
Proceed as planned as the warm air will help you get the extra elevation needed to cross through the pass.
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