Aviation Module 2: Altitude and Flight Performance

Indicated vs True Altitude

• Indicated altitude: the altitude read directly from the altimeter when the Kollsman window is set to the current local atmospheric pressure at sea level (altimeter setting)
• Indicated altitude is affected by factors such as barometric pressure changes and temperature
• Temperature can create non-standard air pressures at various altitudes, misleading the altimeter

True Altitude

• True altitude: the actual height above mean sea level (MSL)
• Accounts for varying environmental factors such as non-standard pressure and temperature
• Crucial for maintaining terrain clearance and airspace requirements

Absolute Altitude

• Absolute altitude: the height above the ground directly beneath the aircraft (Above Ground Level, AGL)
• Important for avoiding terrain and obstacles, especially during low-level flying, takeoffs, and landings

Pressure and Density Altitude

• Pressure altitude: the height above the standard datum plane (29.92 inches of mercury or 1013.25 millibars)
• Standardization is crucial for altitude reporting and safety
• Density altitude: pressure altitude adjusted for non-standard temperature
• Affects aircraft performance, particularly takeoff roll distance, climb rate, and overall capability

Importance of Understanding Altitudes

• Understanding indicated, true, absolute, pressure, and density altitude is critical for navigation, safety, and compliance with air traffic control requirements
• Accurate altitude readings ensure safe separation between aircraft and adherence to flight levels

Indicated Altitude

• The altitude read directly from the altimeter in the cockpit when set to the current local barometric pressure at mean sea level.
• The primary altitude reference in the cockpit for maintaining vertical separation from terrain and other aircraft.
• Affected by factors such as barometric pressure changes and temperature.

True Altitude

• The vertical distance of the aircraft above mean sea level (MSL).
• The actual elevation above sea level, which can differ from the indicated altitude due to variations in atmospheric pressure and temperature.
• Crucial for creating accurate flight plans and navigation when flying over mountainous terrain or when required to maintain a specific altitude above ground level.

Absolute Altitude

• The height of the aircraft above the Earth's surface directly beneath it (above ground level, AGL).
• Important for avoiding terrain and obstacles, especially during low-level flying, takeoffs, and landings.
• Determined using instruments like radar altimeters or visual reference to the ground.

Pressure Altitude

• The altitude indicated when the altimeter setting window is adjusted to 29.92 inches of Mercury (inHg) or 1013.2 millibars (hPa), representing standard atmospheric pressure at sea level under International Standard Atmosphere (ISA) conditions.
• Used as a basis for flight levels above the transition altitude.
• Critical for performance calculations since it is unaffected by temperature and non-standard pressure conditions.

Density Altitude

• The altitude relative to the standard atmosphere conditions (ISA) at which the air density would be equal to the air density at the actual location.
• Pressure altitude corrected for non-standard temperature.
• Affects aircraft performance, with higher density altitudes indicating lower air density, which reduces engine power output, propeller efficiency, and aerodynamic lift.

Importance of Understanding Altitudes

• Critical for navigation, safety, and compliance with air traffic control requirements.
• Understanding the differences between indicated, true, absolute, pressure, and density altitude is essential for pilots to ensure safe and efficient flight operations.

Indicated vs True Altitude

• Indicated altitude: the altitude read directly from the altimeter when the Kollsman window is set to the current local atmospheric pressure at sea level (altimeter setting)
• Indicated altitude is affected by factors such as barometric pressure changes and temperature
• Temperature can create non-standard air pressures at various altitudes, misleading the altimeter

True Altitude

• True altitude: the actual height above mean sea level (MSL)
• Accounts for varying environmental factors such as non-standard pressure and temperature
• Crucial for maintaining terrain clearance and airspace requirements

Absolute Altitude

• Absolute altitude: the height above the ground directly beneath the aircraft (Above Ground Level, AGL)
• Important for avoiding terrain and obstacles, especially during low-level flying, takeoffs, and landings

Pressure and Density Altitude

• Pressure altitude: the height above the standard datum plane (29.92 inches of mercury or 1013.25 millibars)
• Standardization is crucial for altitude reporting and safety
• Density altitude: pressure altitude adjusted for non-standard temperature
• Affects aircraft performance, particularly takeoff roll distance, climb rate, and overall capability

Importance of Understanding Altitudes

• Understanding indicated, true, absolute, pressure, and density altitude is critical for navigation, safety, and compliance with air traffic control requirements
• Accurate altitude readings ensure safe separation between aircraft and adherence to flight levels

Learn about the differences between indicated and true altitude in aviation, essential for flight performance and safety. Understand altitude in all its forms and variations.