Instruments

Static Pressure

Static pressure is the pressure of the surrounding atmosphere.

It acts equally in all directions and decreases as altitude increases.

Static pressure is sensed through the aircraft's static vent or static port.

It is used by the:

• airspeed indicator
• altimeter
• vertical speed indicator

Dynamic Pressure

Dynamic pressure is produced by the movement of the aircraft through the air.

It depends on:

• airspeed
• air density

As airspeed increases, dynamic pressure increases.

As air density increases, dynamic pressure also increases.

Total Pressure

The forward-facing pitot tube senses total pressure.

Total pressure consists of:

Static Pressure + Dynamic Pressure

The airspeed indicator compares total pressure from the pitot tube with static pressure from the static system.

The Pitot-Static System

The pitot-static system provides pressure information to the:

• Airspeed Indicator (ASI)
• Altimeter
• Vertical Speed Indicator (VSI)

The system uses:

• a pitot tube to sense total pressure
• a static vent to sense atmospheric static pressure

Static Vent

The static vent consists of one or more openings positioned where the airflow around the aircraft will provide an accurate measurement of atmospheric pressure.