Altitude where the rate of climb equals 0 ft/min is called the ____.

• A. Absolute ceiling
• B. Service ceiling
• C. Cruise altitude
• D. Maximum altitude

Answer: (A)

The altitude at which the rate of climb becomes zero is the absolute ceiling. As you climb, air becomes thinner, which reduces engine/prop efficiency and decreases lift relative to weight. The airplane can climb only while there’s excess thrust available to overcome drag. When you reach the absolute ceiling, even with maximum power, there isn’t enough excess thrust to produce any upward acceleration, so vertical speed is zero and you can’t climb higher. Below that, you still can climb, and at the service ceiling the climb rate is very small (often about 100 ft/min). Cruise altitude is simply where you typically stay for efficient flight, not a maximum climb limit, and maximum altitude is a less precise term that doesn’t specify the zero-climb condition.