Atmospheric Pressure and Altimeter Concepts

These flashcards provide key vocabulary terms and definitions related to atmospheric pressure, altimeter concepts, and their importance in aviation.

Atmospheric Pressure

The pressure exerted by the weight of the air above a given point.

Standard Day

A reference point in aviation defined as a temperature of 15 degrees Celsius (59 degrees Fahrenheit) and a pressure of 29.92 inches of mercury.

Inches of Mercury (Hg)

A unit of pressure measurement commonly used in aviation, where 29.92 inHg is the standard pressure at sea level.

Standard Datum Plane (SDP)

The reference pressure of 29.92 inches of mercury used for altimeter settings.

Pitot Static System

The system used in aircraft to measure dynamic pressure and static pressure for airspeed and altitude instruments.

Airspeed Indicator

An instrument that shows the aircraft's speed through the air, part of the pitot static system.

Altimeter

An instrument that measures an aircraft's altitude by comparing internal pressure to external atmospheric pressure.

Vertical Speed Indicator (VSI)

An instrument that shows the rate of ascent or descent of an aircraft.

Ram Air

The air entering the pitot tube as the aircraft moves through the atmosphere.

Static Port

A component of the pitot static system that measures the atmospheric pressure outside the aircraft.

Alternate Static Port

A backup port in the cockpit used when the primary static port is blocked.

Indicated Altitude

The altitude displayed on the altimeter when set to the current local atmospheric pressure.

True Altitude

The actual height of the aircraft above sea level, expressed in feet.

Absolute Altitude

The vertical distance between the aircraft and the ground below, measured in feet above ground level (AGL).

Pressure Altitude

The altitude indicated on the altimeter when it is set to 29.92 inches of mercury.

Density Altitude

Pressure altitude corrected for non-standard temperature, representing how the aircraft performs in the atmosphere.

High to Low, Look Out Below

A reminder that descending into lower pressure can lead to being at a lower altitude than indicated by the altimeter.

Colstman Window

A small window on the altimeter used to set the current altimeter setting based on local atmospheric pressure.