METAR TAF

Which of the following considerations is most relevant to a Remote PIC when evaluating unmanned aircraft performance?

• Current weather conditions

• The number of available ground crew

• The type of sUAS operation

Answer explanation

Weather factors can greatly influence sUAS performance and safety of flight.

Tags

NGSS.MS-ESS2-5

Every physical process of weather is accompanied by, or is the result of, a

• movement of air

• pressure differential

• heat exchange

Answer explanation

Every physical process of weather is accompanied by, or is the result of, unequal heating of the

Earth’s surface.

Tags

NGSS.MS-ESS2-5

NGSS.MS-ESS2-6

What causes variations in altimeter settings between weather reporting points?

• Unequal heating of the Earth’s surface

• Variation of terrain elevation

• Coriolis force

Answer explanation

All altimeter settings are corrected to sea level. Unequal heating of the Earth’s surface causes

pressure differences.

Tags

NGSS.MS-ESS2-5

NGSS.MS-ESS2-6

The development of thermals depends on

• a counter-clockwise circulation of air

• temperature inversions

• solar heating

Answer explanation

Thermals are updrafts in convective currents dependent on solar heating. A temperature inversion would result in stable air with very little, if any, convective activity

Tags

NGSS.MS-ESS2-6

How would high density altitude affect the performance of small unmanned aircraft?

• No change in performance

• Increased performance

• Decreased performance

Answer explanation

A combination of high temperature, high humidity, and high altitude result in a density altitude higher than the pressure altitude which, in turn, results in reduced aircraft performance.

Tags

NGSS.HS-PS2-1

If the outside air temperature at a given altitude is warmer than standard, the density altitude is

• equal to pressure altitude

• lower than pressure altitude

• higher than pressure altitude

Answer explanation

If the temperature is above standard, the density altitude will be higher than pressure altitude.

What are the standard temperature and pressure values for sea level?

• 15°C and 29.92” Hg

• 59°C and 1013.2 millibars

• 59°F and 29.92 millibars

Answer explanation

Standard sea level pressure is 29.92 inches of mercury (1013.2 mb). Standard sea level temperature is 15°C (59°F).

Which factor would tend to increase the density altitude at a given airport referenced in the weather briefing?

• An increase in barometric pressure

• An increase in ambient temperature

• A decrease in relative humidity

Answer explanation

On a hot day, the air becomes “thinner” or lighter, and its density is equivalent to a higher altitude in the standard atmosphere, thus the term “high density altitude.”

What affect does high density altitude have on the efficiency of a UA propeller?

• Propeller efficiency is increased

• Propeller efficiency is decreased

• Density altitude does not affect propeller efficiency

Answer explanation

The propeller thrust in proportion to the mass of air being accelerated through the rotating blades. If the air is less dense, propeller efficiency is decreased.

What effect does humidity have on performance?

• It has no effect on performance

• It increases performance

• It decreases performance

Answer explanation

An increase in air temperature or humidity, or a decrease in air pressure (which results in higher density altitude) will significantly decrease both power output and propeller efficiency.