Definition
The hazard in which significant amounts of standing or flowing water on a runway, taxiway, or ramp are drawn into a piston engine's induction system, causing partial or total loss of engine power. Water can enter through the air intake or be thrown up by the propeller and tires, disrupting the air-fuel mixture or hydraulically locking the cylinders.
Plain English
When an aircraft taxis or takes off through standing water, the engine can suck water into the place where it normally sucks in air. Engines need air to run, so taking in water instead can make the engine stumble or quit.
Context Anchor
Seen in discussions of flight through heavy rain, spray, wet runway operations, and conditions where water can be drawn into the engine intake.
Derivation
Ingestion comes from the Latin ingerere, meaning 'to carry in.' In aviation it refers to anything pulled into an engine's intake that shouldn't be there -- water, ice, birds, or debris.
Why Pilots Care
It can produce sudden power loss or engine failure, which is especially hazardous on takeoff or in heavy rain.
Grounding Statement
Picture rain or spray being pulled into the engine opening with the incoming air; if enough water enters, the engine may not keep running smoothly.
Intuition Check
Do not assume this means water in the fuel tanks, and do not assume ordinary rain always causes a problem. Here it means liquid water entering through the engine air inlet, with the concern being enough water to disrupt engine operation.
Example Sentence 1
After the heavy rain, the pilot inspected the runway for standing water to avoid engine water ingestion during the takeoff roll.
Example Sentence 2
Heavy rain increased the risk of engine water ingestion, so the crew monitored engine instruments closely during the approach.