Definition
The breakdown of a chemical compound into simpler substances caused by the application of heat. The heat supplies enough energy to break the chemical bonds holding the original compound together, producing different materials than the one you started with.
Plain English
When something gets hot enough, it doesn't just melt or burn — it actually breaks apart into different chemicals than what it started as.
Context Anchor
Seen in discussions of aircraft fire, overheated materials, smoke, fumes, and fire protection.
Derivation
From Greek 'therme' meaning heat, and Latin 'decomposere' meaning to break apart or separate. So thermal decomposition literally means 'breaking apart by heat.'
Why Pilots Care
Some fire-extinguishing agents and aircraft materials produce toxic byproducts when they thermally decompose. For example, Halon breaks down in a fire and can produce harmful gases, which is why ventilation matters after discharge in an enclosed cockpit.
Grounding Statement
Think of an egg in a hot pan: the heat doesn't just warm it — it permanently changes it into something chemically different. That's thermal decomposition in everyday form.
Intuition Check
Thermal decomposition is not the same as burning. Heat can break a material down before you see any flame.
Example Sentence 1
When a Halon fire extinguisher is discharged onto a hot engine fire, thermal decomposition of the agent can release irritating gases.
Example Sentence 2
The inspection revealed thermal decomposition of the wiring insulation where temperatures had exceeded limits.