This video says about itself:
Alaska’s Erupting Bogoslof Volcano Triggers Highest Aviation Alert
30 May 2017
The eruption of the state’s most active volcano lasted for 55 minutes Sunday and sent a massive plume of ash up to 45,000 feet into the atmosphere.
Planes flying between North America and Asia use the route above the volcano that’s in the Aleutian Islands chain as a key flight path, though there were no reports of problems with aircraft following this eruption.
Seismic activity on the island has been low since Sunday, but another eruption could occur at any time without warning, noted monitors at the Alaska Volcano Observatory.
“Bogoslof Volcano remains at a heightened state of unrest and in an unpredictable condition,” said a statement from the observatory. “Activity may ramp back up with additional explosions producing high-altitude volcanic clouds with little precursory activity.”
Monitors were tracking a cloud of white-gray ash from Sunday’s eruption that was drifting north. Authorities lowered the alert level later that day from red to orange.
Aircraft engines can suck in volcanic ash, which can melt and coat the mechanisms, ultimately leading to engine failure. A major eruption of the Eyjafjallajokull volcano in Iceland in April 2010 caused Europe’s largest air-traffic shutdown since World War II.
This current sequence of seismic activity of frequent eruptions and volcanic lightning started on Bogoslof in December 2016. There were 36 eruptions from January to March on the island, which is less than a half mile wide.
See also here.