Plain English Meaning

A little open-ended tube pointing into the wind on the outside of the airplane. As the airplane moves forward, air pushes into the tube, and the strength of that push is used to measure how fast the airplane is flying through the air.

Full Definition

A small forward-facing tube mounted on the outside of an aircraft that captures the pressure of oncoming air during flight. This captured pressure, called ram or impact pressure, is fed to the airspeed indicator, where it is compared with static (still) air pressure to produce an airspeed reading.

Context Anchor

You see it during preflight inspection, airspeed system discussions, and situations such as slips where airflow may hit the airplane from an unusual angle.