Alaskan volcano's ash cloud grounds flights
Strong winds on Monday pushed an ash cloud from an Alaska volcano into the heart of the state, grounding flights and limiting travel to western and northern communities. However, authorities also downgraded the volcano alert level, saying the intensity of the eruption had "declined significantly." The Pavlof volcano, one of Alaska's most active volcanoes, had erupted at 4pm local time on 27 March.
Mount Pavlof: An overview
Mount Pavlof is one of the most active in the United States since 1980, with eruptions recorded in 1980, 1981, 1983, 1986–1988, 1996–1997, 2007, 2013, and twice in 2014 The US Geological Survey has prescribed a threat score of 95 for Mt Pavlof due to the risk it poses to air traffic. The USGS is working on improving monitoring infrastructure on Mt Pavlof.
Volcanic ash: A threat to flights
An eruption of Mount Redoubt (Alaska) in December 1989 sent out an ash cloud 240 km that flamed out the jet engines of a KLM flight carrying 231 passengers to Anchorage. The jet dropped more than four km before pilots were able to restart the engines and land safely.
An open system volcano
Geologists call Pavlof an open system volcano. Magma can move to the surface much more easily as compared to regular volcanoes. The movement comes with little shaking of the ground, making it difficult to predict the onset of an eruption.
Which flights were grounded as a result?
Alaska Airlines has canceled 41 flights to and from six cities in northern Alaska including all flights operating to and from Fairbanks. The canceled flights affect 3,300 passengers. Flights are suspended to Barrow, Bethel, Fairbanks, Kotzebue, Nome and Prudhoe Bay until Alaska is able to assess weather reports. "We simply won't fly where ash is present," said John Ladner, Alaska's director of operations.
What threats does the volcano pose to aircraft?
One of the most significant threats is reduced visibility and interference with communication equipment, due to charged particles in the ash. Volcanic ash is angular and sharp and has been used as an industrial abrasive. The powdered rock can also cause a jet engine to shut down. Experts compare a volcanic ash cloud to flying into the path of a sand blaster.
