What is the maximum altitude at which, in standard atmosphere, it is possible to maintain, at a specified rotational speed, a specified power or a specified manifold pressure?

What is the maximum altitude at which, in standard atmosphere, it is possible to maintain, at a specified rotational speed, a specified power or a specified manifold pressure?

• A. Critical Altitude
• B. Service Ceiling
• C. Absolute Ceiling
• D. Cruise Altitude

Answer: (A)

Critical altitude is the highest altitude at which, in standard atmosphere, you can maintain a chosen RPM while delivering a specified power or maintaining a specific manifold pressure. As you climb, air density drops, and the engine (especially with boost) can only compensate up to a limit. Below this altitude, the turbocharger (or engine) can sustain the target manifold pressure and power, so the specified RPM/power can be maintained. Above it, the manifold pressure falls off and you can no longer hold the required setting, so power cannot be maintained. The other terms describe different performance or flight limits (service ceiling, absolute ceiling, cruise altitude) and do not define this specific boundary.

Critical altitude is the highest altitude at which, in standard atmosphere, you can maintain a chosen RPM while delivering a specified power or maintaining a specific manifold pressure. As you climb, air density drops, and the engine (especially with boost) can only compensate up to a limit. Below this altitude, the turbocharger (or engine) can sustain the target manifold pressure and power, so the specified RPM/power can be maintained. Above it, the manifold pressure falls off and you can no longer hold the required setting, so power cannot be maintained. The other terms describe different performance or flight limits (service ceiling, absolute ceiling, cruise altitude) and do not define this specific boundary.