Definition
A protective cap or sleeve fitted over the open end of an aircraft's pitot tube while the aircraft is parked, used to prevent insects, dirt, water, and debris from entering and blocking the tube. It is removed during preflight inspection before flight.
Plain English
A small cover that goes over the front of the pitot tube on the ground to keep bugs and dirt out. It must be taken off before flying.
Context Anchor
Seen during preflight inspection, especially when checking the pitot-static system for possible blockage.
Derivation
Named after the pitot tube it protects. 'Pitot' comes from Henri Pitot, the 18th-century French engineer who invented the tube used to measure fluid speed. The cover is simply the protective fitting for that tube.
Why Pilots Care
If left in place, it blocks ram air pressure, producing zero or erroneous airspeed indications that can lead to loss of control on takeoff.
Intuition Check
Do not treat a pitot tube cover as just a parking accessory. If it is still installed before takeoff, it blocks the air inlet needed for airspeed indication.
Example Sentence 1
During preflight, the pilot removed the pitot tube cover and stowed it in the side pocket of the cockpit.
Example Sentence 2
The cover was left on overnight and the airspeed indicator remained at zero throughout the takeoff roll.