Definition
A model used in fire safety and firefighting that identifies the three elements required for combustion to occur: fuel, heat (an ignition source), and oxygen. If any one of these three elements is removed, combustion cannot take place and an existing fire will go out.
Plain English
A simple way of showing that a fire needs three things to burn — something to burn, something to light it, and air. Take away any one of the three and the fire stops.
Context Anchor
Seen in aircraft fire prevention, engine fire, electrical fire, and fire-extinguisher discussions.
Derivation
Called a 'triangle' because three sides are the minimum needed to form a closed shape. Remove any one side and the shape collapses — the same way removing any one element collapses a fire.
Why Pilots Care
Knowing which element to remove guides correct use of fire bottles, fuel shutoff valves, and emergency checklists.
Analogy
Think of it like a three-legged stool. If one leg is missing, the stool cannot stand; if one part of the fire triangle is missing, the fire cannot keep burning.
Grounding Statement
If fuel is leaking near a hot engine part and air is present, all three parts of the fire triangle are in place.
Intuition Check
Do not think of the fire triangle as a physical triangle in the airplane. It is a simple model showing the three conditions a fire needs: fuel, oxygen, and heat.
Example Sentence 1
When the instructor explained engine fires, he pointed to the fire triangle and showed how pulling the mixture to idle cut-off removes the fuel side.
Example Sentence 2
During the preflight the mechanic checked for fuel leaks that could supply one side of the fire triangle.