What to Do in an Inadvertent Encounter

摘要

If your aircraft manual does not contain specific guidance on handling a volcanic ash encounter, the following is a compilation of recommended actions from the International Civil Aviation Organization, NASA and Boeing publications, along with simplified explanations behind them: 1. Immediately reduce thrust to idle. This will lower the temperatures in the hot sections of the engine where ash particles would quickly melt onto critical turbine guide vanes and rotors, as well as plug the cooling vents. The engine core temperatures must be reduced below the temperature at which the ash particles melt and reduction to idle is the only reliable means of doing so. If this action is not taken at or before the first signs of engine malfunction, then flameout is likely to occur. Due to the volcanic ash in the engine possibly accumulating on the surfaces and causing increased back pressures that reduce an engine's surge margins and increase the likelihood of a compressor stall, throttle movements should be slow and smooth.