Definition
Sudden, involuntary muscle contractions throughout the body, often violent and uncontrollable, typically caused by a disturbance of normal brain function. In aviation medical contexts, convulsions can result from oxygen deprivation, exposure to high concentrations of carbon dioxide (such as from sublimating dry ice), or other physiological stressors that affect the central nervous system.
Plain English
Sudden, uncontrolled shaking or jerking of the body caused by something going wrong in the brain. The person cannot stop it from happening.
Context Anchor
Seen in warnings about carrying dry ice, which can release carbon dioxide gas inside an aircraft if the area is not well ventilated.
Derivation
From the Latin convulsio, meaning 'to pull violently' or 'to tear together.' The original sense of being violently pulled fits the modern meaning: the body is seized by forces it cannot control.
Why Pilots Care
CO2 buildup from dry ice can rapidly incapacitate crew, leading to loss of control or emergency descent.
Grounding Statement
A person having convulsions is not simply moving around; their body is jerking beyond their control.
Intuition Check
Do not read convulsions as ordinary shaking from cold or fear. In this context, convulsions mean severe uncontrolled body movements that can signal a dangerous medical condition.
Example Sentence 1
The handbook warns that high carbon dioxide levels in the cabin from sublimating dry ice can cause headaches, dizziness, and eventually convulsions.
Example Sentence 2
The pilot ventilated the cabin at the first sign to prevent convulsions from developing.