Definition
The amount of force applied per unit of area. In aviation maintenance it is commonly expressed in pounds per square inch (psi), inches of mercury (in. Hg), or pascals, and is measured in fluids (liquids and gases) acting against the walls of their container or against a surface.
Plain English
How hard something is pushing on a given amount of surface. If you press your thumb on a table, the harder you push, the more pressure you create on the spot under your thumb.
Context Anchor
Seen in aircraft tires, oil systems, fuel systems, brake systems, weather reports, cabin systems, and instrument indications.
Derivation
From the Latin pressura, meaning 'a pressing.' That is exactly what pressure is: the result of one thing pressing against another, measured per unit of area.
Why Pilots Care
Correct pressure levels are required for brakes, flight controls, engines, and tires to function safely; incorrect values can lead to system failure or loss of control.
Grounding Statement
If air is squeezed into a smaller space, it pushes harder against the walls around it, so its pressure rises.
Intuition Check
Pressure does not mean stress, urgency, or being rushed here. In aviation maintenance, it means a physical pushing force spread over an area, usually shown by a gauge or instrument.
Example Sentence 1
Before the first flight of the day, the technician checked tire pressure against the value listed in the maintenance manual.
Example Sentence 2
Low tire pressure was noted during the preflight walk-around and corrected before engine start.