Definition
A supplemental oxygen system in which oxygen is generated on demand by the chemical reaction of a solid block (the 'candle'), typically sodium chlorate mixed with iron, which when ignited produces breathable oxygen for a fixed duration. Once started, the reaction cannot be stopped and the candle burns until exhausted.
Plain English
A backup oxygen source that makes its own oxygen by burning a solid chemical block instead of releasing it from a pressurized bottle. Once it lights, it keeps producing oxygen until the block is used up.
Context Anchor
Seen in aircraft passenger emergency oxygen systems and in maintenance procedures for oxygen generators installed above passenger seats or in service areas.
Derivation
Called a 'candle' because the solid chemical block burns slowly from one end to the other, much like a wax candle. The output, however, is breathable oxygen rather than light.
Why Pilots Care
Provides a reliable, long-duration oxygen supply during sudden depressurization without depending on finite compressed-gas cylinders.
Grounding Statement
When the unit is activated, a solid chemical inside gets hot and releases oxygen for the masks until the chemical is used up.
Intuition Check
Do not picture a normal wax candle with an open flame. In aviation, a chemical oxygen candle is a sealed oxygen generator that produces breathable oxygen through a controlled internal reaction.
Example Sentence 1
When the cabin lost pressure, the passenger masks dropped and a chemical oxygen candle system began supplying oxygen to each row.
Example Sentence 2
During preflight, the technician verified that all chemical oxygen candle systems were within their expiration dates.