Altitude where the rate of climb equals 100 ft/min is called the ____.

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

Answer: (A)

In aviation performance terms, as you climb, air becomes thinner and engine/wing efficiency drops, so the rate of climb falls with altitude. The service ceiling is defined as the altitude where the aircraft’s rate of climb has fallen to about 100 feet per minute. That means you can still climb, but very slowly, at and near that altitude. Above it, the climb rate would be less than 100 fpm. The absolute ceiling, in contrast, is the altitude where the rate of climb drops to zero, meaning you can’t climb at all. Cruise altitude is simply a typical altitude used for cruising, not a defined climb-rate threshold, and maximum endurance altitude relates to endurance (time aloft) rather than climb rate. So the correct choice is service ceiling.