Yes. Encounters between aircraft and clouds of volcanic ash are a serious concern. Jet engines and other aircraft components are vulnerable to damage by fine, abrasive volcanic ash, which can drift in dangerous concentrations hundreds of miles downwind from an erupting volcano.
In the past, many aircraft have accidentally encountered volcanic ash clouds, and in some cases jet engines have temporarily lost power. An international consortium of government agencies (including the USGS, the Federal Aviation Administration, and the National Weather Service), now monitors ash-producing volcanoes and tracks volcanic ash clouds to reduce the likelihood of future encounters.