Critical Altitude

Critical altitude is the maximum altitude at which a supercharged or turbocharged engine can maintain its rated sea-level manifold pressure (and therefore its rated power). Above the critical altitude, the engine is operating normally-aspirated and power decreases with altitude. Below it, the turbocharger or supercharger maintains full power.

Significance for Operations

Turbocharged aircraft such as the Cessna 182RG Turbo or Piper Turbo Arrow can maintain sea-level power to their critical altitude (typically 16,000–20,000 ft). Above that, power drops like a normally-aspirated engine. For high-altitude operations, knowing the critical altitude of the engine is essential for performance planning.

Related Terms

See also: Full Throttle Altitude, Manifold Pressure, Density Altitude.