Definition
The amount of electrical charge a battery or capacitor can store, or the maximum quantity a container, system, or component can hold or carry. In aviation, capacity is most commonly used to describe battery storage (measured in ampere-hours), fuel tank volume (gallons or liters), and the load-carrying ability of an aircraft, structure, or system.
Plain English
How much something can hold or store before it is full or maxed out.
Context Anchor
Seen in aircraft loading, fuel systems, electrical systems, seating limits, and airport or runway traffic discussions.
Derivation
From the Latin capax, meaning 'able to hold.' That root carries straight into the aviation sense: capacity is the measure of how much a thing is able to hold, store, or carry.
Why Pilots Care
Exceeding capacity changes takeoff distance, climb rate, stall speed, and structural loads, directly affecting safety and legality.
Intuition Check
Capacity does not mean the amount present right now. It means the limit or stated amount something can hold, carry, or deliver.
Example Sentence 1
The battery has a capacity of 35 ampere-hours, which means it can supply roughly 35 amps for one hour before being fully discharged.
Example Sentence 2
Runway capacity at the airport drops during low-visibility operations.