Question 15
Domain 6: FAA Part 107 PerformanceWhat effect does high density altitude have on UAS performance?
Correct answer: B
Explanation
High density altitude means the air is less dense, so the UAS rotor system produces less lift and must work harder to stay aloft. Warmer, thinner air also reduces battery efficiency because the aircraft needs more power for the same performance.
Why each option is right or wrong
A. Increased lift and shorter takeoff distance
B. Decreased lift and reduced battery efficiency
Under FAA guidance, density altitude is the pressure altitude corrected for nonstandard temperature, and higher density altitude means lower air density. In that thinner air, rotor/propeller thrust and lift are reduced, so the UAS must draw more power to maintain altitude; the FAA’s UAS knowledge materials also note that battery performance degrades in hot conditions, which further shortens endurance.
C. No effect on electric-powered UAS
D. Improved propeller efficiency