Which climb performance yields the greatest altitude gain per unit time?

• A. Best angle of climb (Vx)
• B. Service ceiling
• C. Absolute ceiling
• D. Best rate of climb (Vy)

Answer: (D)

This item tests climb performance in terms of how fast you gain altitude. The greatest altitude gain per unit time is achieved by the best rate of climb, Vy, because Vy represents the maximum vertical speed the airplane can sustain with the available power and aerodynamics. When you fly at Vy, you’re climbing as fast as possible in feet per minute, even if you’re not climbing as steeply as you would at other speeds.

In contrast, the best angle of climb (Vx) gives the most altitude for a given forward distance, which is a climb-per-horizontal-distance concept, not a climb-per-time concept. The service ceiling and absolute ceiling describe altitudes where the climb rate has fallen to a small value or zero, respectively, and don’t indicate the fastest possible vertical speed.