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Why Airplanes Cannot Fly Under an Ash Cloud

By Edited Oct 16, 2015 1 4

When Iceland's Eyjafjallajokull volcano erupted in April 2010 it shot up a lot of volcanic ash that closed airports for days with flights halted indefinitely, which turned out to last approximately a week. Due to continuing activity from Eyjafjallajokull in the month of May that year, additional suspensions of flights in England and Ireland were also put into place, along with well over a dozen other countries. 1 Millions of people were stranded when more than 100,000 flights were interrupted.

Eyjafjallajokull volcano/dust storm
Credit: Andrea Schaffer on Flickr/CC by 2.0 with Attribution

Photo description on Flickr by author: Dust storm at base of Eyjafjallajökull volcano

Speculations had been made that these kinds of events may continue through as summer approached with the uncertainty based on the heavy level of volcanic activity occurring at the time. This caused a lot of anxiety for both commercial and passenger flights. Earlier this year Chile's Calbuco volcano erupted in late April and created major delays and cancellations in Buenos Aires.

While more has been learned since 2010, ash clouds are still a problem. Here's why:

Ash Clouds Put People at Risk

In 1982 a British Airways flight flew over a cloud of volcano ash when flying over Indonesia and experienced a failure of all four engines. Fortunately, this did not result in fatality, however everyone was saved by the pilots being able to glide the aircraft out of the ash cloud and divert to Jakarta and perform a safe landing.

A few years later, KLM flew over what they thought was a regular cloud that turned out to be an ash cloud from Mount Redoubt in Alaska. In this emergency all four engines, just like the 1982 flight, failed along with the standby electrical system. In this situation the crew managed to restart the engines and land safely.

Another concern is due to the way ash particles can cause significant damage to an airplane. Ash particles floating downward can enter an aircraft's rotors, flight controls and/or engines and cause damage.

A report by CNN in 2010 stated one aircraft manufacturer, Airbus, explained how experience had previously demonstrated costly damage to the planes from the ash clouds. These tiny particles can basically do huge damage. The ash can harm aircraft surfaces, windshields, and contaminate and/or block proper ventilation, hydraulic, electronic and air systems. The company experts also explained moving parts have a potential to be eroded and partial or complete blocking of fuel nozzles can occur. 3

"Volcanic ash is kind of like grit or sandpaper," said John Hansman, a professor of Aeronautics and Astronautics at MIT told Accuweather in May 2015.  "If it goes into the engines and is the right size, it can cause the engines to shut down."

Any serious interference can essentially cause jet engines to fail, which endangers all of the passengers and crew on board.  

While these two flights were extremely lucky, that might not always be the case. If the ash effectively creates problems described above, aircraft can literally fall out of the sky and crash to the ground. Thus the industry proceeds with caution when volcanic eruptions occur.

Ash Clouds Create Visual Disruption

Once the 2010 eruptions occurred, the question arose why airplanes could not simply fly under the ash cloud where visibility is clearer. While that sounds good in theory, the problem is that visibility for pilots is not the only issue when ash clouds occur. CNN reported on April 16, 2010 the U.S. Geological Survey said:

"Encounters between aircraft and volcanic ash can happen because ash clouds are difficult to distinguish from ordinary clouds, both visually and on radar". 3

Flying over an ash cloud is also not an option because if anything (related to the volcanic eruption or not) would create a situation where an emergency landing would be extremely difficult, if not impossible.

United airplane at Denver Airport
Credit: Leigh Goessl/All rights reserved

During a volcanic eruption, the ash clouds can carry far, causing planes to be grounded.

Ash Can Cause Expensive Damage

Even if planes do not cease running while running under, over or through an ash cloud, the damage incurred to a single aircraft can cost millions of dollars to repair, if it is repairable at all. This could seriously hurt an airline’s financial status and further disrupt flights. Not to mention the expense would probably be passed on to passengers in the form of increased ticket prices.  

Aviation Safety Cannot Be Ignored

Volcanic eruptions that cause disruption of the airline industry with planes being grounded is obviously concerning to many due to economic impacts, including but not limited to the air industry, businesses and commercial tourism. However, safety is still an important factor as well and cannot be ignored. Experience has shown the risk of aircraft damage and failure is too high to chance putting people and aircraft in danger when ash clouds are present.

Tools Developed for Risk Management

Fortunately, today some progress has been made where it comes to volcanic interruptions where flights are concerned. Technology has progressed to the point where pilots can now “see” the ash clouds through infra-red imaging. According to Popular Mechanics, they can now see any hazards from ash 60 miles ahead up to 50,000 feet.  It also sends data to ground crews to help assess and ascertain the dangers, allowing them to effectively analyze the size of an ash cloud to determine which routes need closing off. This technology is called “AVOID” which stands for “Airborne Volcanic Object Imaging Detector”. 4

Volcano Plume Continues Blowing East Over Argentina to Atlantic Ocean (2011)
Credit: NASA Goddard Space Flight Center on Flickr/CC by 2.0 with Attribution

Other technologies allow experts to assess the ash density to make better decisions of whether it is safe to fly through or not where low or medium ash density is present. Other radar and satellite systems developed in Iceland can now better predict which direction ash will go.

The risk of volcanic eruption in various regions of the world is a constant threat. While some volcanoes may be somewhat predictable, most of them are not. They can lie dormant for decades or centuries then have a sudden rouse from slumber. However, with a combination of knowledge, technology and risk management procedures in place, better planning and methods of dealing with eruptions when they do occur can cause less damage and, more importantly, ensure people are safe.

 

Other related articles you may be interested in:

Why Iceland's Volcanoes are Considered Dangerous

 Three Highly Dangerous Active Volcanoes in South America

What is a 'Dirty Thunderstorm'?

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Comments

May 16, 2015 12:57am
HLesley
This article brought back a few memories. We had a neighbor who was stranded in Europe because of the ash cloud, and we were scheduled to fly to Europe shortly after so were in a bit of a panic about what was going to happen. The dust seemed to settle fairly quickly though - literally.
May 16, 2015 3:48am
LeighGoessl
Thanks HLesley for reading and commenting. That must have been a difficult time for those stranded (or about to travel like you were - the uncertainty!) Hopefully, the tools being developed will help.
May 16, 2015 6:47pm
mycini
THanks for writing.
May 18, 2015 7:37am
LeighGoessl
Thanks for commenting. Welcome to IB!
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Bibliography

  1. "Why Airplanes Can't Fly through Ash Clouds." International Business Times. 15/06/2011. 20/04/2015 <Web >
  2. "Holidaymakers warned of risk of 'significant disruption' if Icelandic volcano erupts." The Telegraph. 19/08/2014. 20/04/2015 <Web >
  3. "Explainer: Why ash cloud endangers aircraft." CNN. 16/04/2010. 20/04/2015 <Web >
  4. "Volcanoes vs. Airplanes: How Big Is the Risk?." Popular Mechanics. 03/09/2014. 20/04/2015 <Web >
  5. " Volcanic Eruptions and Air Travel: What Happens When a Plane Flies Through an Ash Plume?." Accuweather.com. 9/05/2015. 16/10/2015 <Web >

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