Why planes don’t fly during a volcanic eruption

Hawaii's Mount Kilauea.

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Hawaii’s Mount Kilauea.
source
USGS

  • Hawaii’s Mount Kilauea erupted Thursday morning at 4:00 a.m. local time.
  • The eruption sent ash clouds as high as 30,000 feet.
  • Ash clouds wreak havoc on modern airliners and their jet engines.

On Thursday, Mount Kilauea on Hawaii’s Big Island erupted at 4:00 a.m. local time on Thursday. The explosive eruption sent ash clouds 30,000 feet in the air and has forced more than 1,000 people to flee.

Kilauea’s eruptions have been building in intensity over the past couple of weeks. Earlier this week, the US Geological Survey raised its alert level to red, indicating that a major eruption is imminent and is a hazard to those on the ground and in the air.

Not only can eruptions rain down debris and leave rivers of lava, volcanic ash in the air can wreak havoc on commercial airliners.

The most famous run-in between a plane and a volcano occurred on June 24, 1982, when British Airways Flight 009 inadvertently flew through an ash cloud emitted by an erupting Mount Galungung.

At the time, the Boeing 747 was cruising at 37,000 feet on its way from Kuala Lumpur, Malaysia, to Perth, Australia, when the flight’s captain was notified of an electric discharge called a St. Elmo’s Fire that enveloped the plane’s engines in an odd glow. In fact, the discharge enveloped all of the 747’s leading edges.

Almost immediately, the jet’s engines began to fail and the cabin filled with a sulfuric smoke.

Soon, all four engines failed, leaving the jumbo jet to glide along while the pilots worked to restart them.

The plane lost 25,000 feet of altitude before the pilots got the engines restarted at 12,000 feet. It was later discovered that molten ash had clogged up the jumbo’s four Rolls-Royce turbofan engines. By the time the plane reached 12,000 feet, the ash had cooled, solidified, and broken off; allowing the engines to start again.

But the ash had also caused other issues for the pilots. Even with the engines restarted, poor visibility made flying difficult. The ash had been effectively sandblasting the plane at 350 mph which turned the front windows nearly opaque. Fortunately, the pilots were able to land at Jakarta Airport using a side window. All 248 passengers and 15 crew on board the plane made it to safety.

All four engines, as well as the 747, were severely damaged as a result of the incident.

In 1989, KLM experienced a similar incident when one of its 747-400s suffered quadruple engine failure after flying through an ash cloud emitted by Mout Redoubt in Alaska. Again, the flight was able to restart its engines after descending to 13,000 feet and make an emergency landing in Anchorage.

Fortunately for those of us flying, airlines have learned their lesson. Flying near volcanic eruptions is dangerous for everyone involved and very expensive for the airlines.