2.3 The Operating Environment and Aircraft Performance

    "The effects of encountering volcanic ash during flight."


          Encountering volcanic ash in-flight has been known to have damaging effects on aircraft such as surface abrasion, and loss of pilot visibility. When ash is sucked into jet engines, it can melt and then re-solidify in cooler parts of the engine reducing the performance, and even causing engine stress.
           It has been known also that volcanic ash can cause avionics and electrical equipment to fail. "Encounters of Aircraft with Volcanic Ash Clouds: A Compilation of Known Incidents, 1953-2009 documents 79 damaging ash/aircraft encounters. Twenty-six of those involved significant to very severe aircraft damage, including nine encounters where engine failure occurred during the flight."  (Volcano Hazards Program, 2015) Luckily, according to the NTSB, there have been no known plane crashes or fatalities recorded due to ash ingestion, but it has become an important part of flight training. Student pilots need to understand the importance of recognizing dangers to their aircraft, and even though no fatalities have occurred due to ash, no one wants to be the first.
            The ICAO has taken action to globally mitigate the effects and risks associated with flying through areas with possible ash deposits. There are published steps which can be taken to ensure safe flying as stated below...

"Report eruptions that are imminent or underway."

"Detect ash clouds in the atmosphere and forecast their expected movement hours into the future."

"Issue special warning messages to aviation meteorological offices, airline operation centers, and air-traffic management centers."

 (Volcano Hazards Program, 2015)     

             The first line of defense against ash hazards is knowledge and communication. Reporting eruptions in a timely fashion will give pilots enough time to make critical decisions allowing them to deviate from potentially hazardous flight patterns. VAAC's, or Volcanic Ash Advisory Centers provide information regarding the movement and location of ash clouds. You can find VAAC advisories in textual and graphical form as SIGMETS. 

              

Reference:

Volcano Hazards Program. (2015, December 14). Volcanic Ash Impacts & Mitigation - Effects on Aircraft. Retrieved from https://volcanoes.usgs.gov/volcanic_ash/ash_clouds_air_routes_effects_on_aircraft.html