Definition
An atmospheric condition, typically found near deep tropical convective storms, in which the air contains a high concentration of small ice crystals suspended in the form of an ice cloud. These crystals can be ingested by jet engines and accumulate inside the engine core, where they melt and refreeze on warm surfaces, potentially causing engine roll-back, flameout, or damage. The condition is often invisible to weather radar because the small ice crystals reflect very little radar energy.
Plain English
Air that holds an unusually heavy load of tiny ice crystals — usually high up near big tropical thunderstorms. The crystals are small enough that radar barely sees them, but enough of them can build up inside a jet engine to cause it to lose power or stop running.
Context Anchor
Seen in high-altitude weather discussions, engine icing guidance, and flight planning around thunderstorms.
Derivation
“Ice water content” means the amount of frozen water contained in a volume of air. “High” means that amount is greater than normal, not that the ice is necessarily easy to see.
Why Pilots Care
High concentrations of ice crystals can trigger engine rollback, flameout, or damage in modern high-bypass turbofans without triggering traditional ice detection systems.
Grounding Statement
Picture cruising at high altitude near a tall tropical thunderstorm: the radar shows clear air ahead, but the aircraft is actually flying through a haze of tiny ice crystals being thrown out the top of the storm.
Intuition Check
Do not assume High Ice Water Content means visible chunks of ice, hail, or obvious ice building up on the wings. In this term, the danger can be many tiny ice crystals that are hard to see but still affect engines and sensors.
Example Sentence 1
The crew gave the line of tropical thunderstorms an extra wide margin at cruise altitude to stay clear of any high ice water content.
Example Sentence 2
The crew noted a sudden drop in engine parameters while transiting a cell known for high ice water content.