Plain English Meaning
Tiny bits of water in the fuel turn into ice when the fuel gets very cold, and that ice can clog the filters and lines that feed fuel to the engine.
Full Definition
The formation of ice within an aircraft's fuel system caused by water suspended or dissolved in the fuel freezing as fuel temperature drops below 0°C. Ice crystals can collect on fuel filters, screens, and lines, restricting or completely blocking fuel flow to the engine. It is most common in turbine aircraft operating at high altitudes for extended periods, where cold-soaked fuel can fall well below freezing.
Context Anchor
Seen in fuel system, preflight, cold-weather operations, and engine power-loss discussions.
Why Pilots Care
Unresolved fuel system icing can cause or total engine power loss during .