For a given true airspeed, the effect of density altitude on lift is to

For a given true airspeed, the effect of density altitude on lift is to

• A. Increase
• B. Decrease
• C. Remain unchanged
• D. Vary with wind

Answer: (B)

Lift at a given true airspeed depends on air density. As density altitude increases, air becomes less dense. Since dynamic pressure is 1/2 ρ V^2, and lift is proportional to dynamic pressure (along with wing area and coefficient of lift), a lower density reduces lift when the true airspeed is held constant. In practical terms, you’d need to increase angle of attack or speed to maintain the same lift, and at higher density altitude the aircraft’s lift potential is reduced, which is why the correct result is that lift decreases. Wind doesn’t affect lift in this scenario, so it doesn’t cause a change here.

Lift at a given true airspeed depends on air density. As density altitude increases, air becomes less dense. Since dynamic pressure is 1/2 ρ V^2, and lift is proportional to dynamic pressure (along with wing area and coefficient of lift), a lower density reduces lift when the true airspeed is held constant. In practical terms, you’d need to increase angle of attack or speed to maintain the same lift, and at higher density altitude the aircraft’s lift potential is reduced, which is why the correct result is that lift decreases. Wind doesn’t affect lift in this scenario, so it doesn’t cause a change here.