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Why you should always park your Aircraft when Volcanic Ash is in your Path

by Jeremy Cox 3. May 2010 11:25
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On April 14th, 2010, both the U.K.’s Civil Aviation Authority (CAA) and its National Air Traffic Services (NATS) and Luftfartstilsynet (Norway’s CAA) made what appears to many as having been a brave but rash decision to close all of its nations airspace (initially Norway closed only its most northern airspace) to all traffic as a result of the eruption of the Icelandic volcano: Eyjafjallokul located in the South-western portion of this small Island Nation.

There appears to be a rising tide of disgruntlement forming amongst the European air-travelling public as well as the employees of the many companies that service this segment, against the sweeping decisions made by both of the CAAs, NATS, Eurocontrol and EASA that a “no-fly” ban to be placed over much of Europe. This ban lasted more than seven days, thus throwing the travel plans of millions into utter chaos, and according to Giovanni Bisignani, the director general and chief executive of IATA “For an industry (Airlines) that lost $9.4bn last year and was forecast to lose a further $2.8bn in 2010, this crisis (the ban) was devastating..."


I personally must contest this negative discourse that is gathering momentum over the decision that was made, because when the facts of the very real dangers that exist within the plume of a volcanic ash cloud are systematically reviewed, it becomes obvious that the right decision was made.

In appendix 2 of the FAAs Airmen Information Manual, you will find a specific form titled: Volcanic Activity Report (VAR) which must be completed and sent to the Global Volcanism Program headquarters at the Smithsonian Institution in Washington, DC. The AIM further states in section:

7-1-27. PIREPs Relating to Volcanic Ash Activity

a. Volcanic eruptions which send ash into the upper atmosphere occur somewhere around the world several times each year. Flying into a volcanic ash cloud can be extremely dangerous. At least two B747s have lost all power in all four engines after such an encounter. Regardless of the type aircraft, some damage is almost certain to ensue after an encounter with a volcanic ash cloud.

b. While some volcanoes in the U.S. are monitored, many in remote areas are not. These unmonitored volcanoes may erupt without prior warning to the aviation community. A pilot observing a volcanic eruption who has not had previous notification of it may be the only witness to the eruption. Pilots are strongly encouraged to transmit a PIREP regarding volcanic eruptions and any observed volcanic ash clouds.

c. Pilots should submit PIREPs regarding volcanic activity using the Volcanic Activity Reporting (VAR) form as illustrated in Appendix 2. If a VAR form is not immediately available, relay enough information to identify the position and type of volcanic activity.

d. Pilots should verbally transmit the data required in items 1 through 8 of the VAR as soon as possible. The data required in items 9 through 16 of the VAR should be relayed after landing if possible.

The two Boeing 747 incidents cited in the AIM are the four-engine flame-outs that occurred to, first on the night of June 24th, 1982 where British Airways flight number 9 dropped from FL370 down to about 10,000 feet M.S.L. after flying through the volcanic plume from Mount Galunggung in West Java, Indonesia; second on December 15th, 1989 where KLM flight number 867, on its way from FL250 to FL390 fell to an altitude below 11,000 feet after flying through the black plume that was being spewed from the erupting Mount Redoubt near Anchorage, Alaska, here in the U.S.A. Fortunately in both cases, some, if not all of the effected engines were restarted, and both aircraft were able to make emergency landings without injury, at a suitable diversionary airport.

Even though there was no loss of life involved in both of these incidents, considerable damage occurred to both aircraft as a result of their unfortunate forays into volcanic ash clouds. 

Most recently in Europe ash damage has been found in the engines of a World Airways MD-11, a Thomas Cook B757, several of the RAF Typhoon Euro-fighters and a Finnish F-18 Hornet. As engine inspections are stepped-up because normal air operations are returning to the skies of Europe, I would be very surprised if more reported examples of engine damage don’t become prominent in the aviation press.

How does volcanic ash cause damage to an aircraft and its engines? Allow me to explain...

The columns of ash that spew from a volcano, normally settle in the flight levels between FL320 and FL350. If seen in daylight, these extensive clouds of debris vary in colour from light brown to jet-black. The worst aspect of them is that they do not show up on Radar.  Every year there are normally 60 volcanic eruptions around the globe. Usually 10 of these are classified as being “major.” Every eruption poses many unknown ash hazards, and normally more than 100,000,000 tons of ash is thrown into the air from any major eruption. The properties of an ash plume are both abrasive and acidic and normally consist of hard, sharp fragments of glass and rock in varying sizes and having high concentrations of Sulphur Dioxide, which when mixed with water, becomes Sulphuric Acid.

All windows, light lenses and leading edges are severely damaged by the abrasive ash encounter. Pitot/static systems become clogged and when on the ground, braking action and traction is severely affected by the ash-bed that lays on a runway or taxi-way.

The lethal danger associated with volcanic ash is how quickly it will cause a flame-out and in-flight shutdown of a gas turbine engine. All of the compressor and turbine blades are severely eroded, causing immediate loss of power. Bleed and cooling airway holes quickly become blocked and immediately start affecting the normal airflow through the engine. The fuel-air mixture rapidly becomes too rich, and the engines flame-out. Before the engines do rich-cut, the chances are extremely high that enough igneous rock debris has made it through the hot section of the engine to start reforming as a glass coating or build up on many of the interior components. It goes without saying that if the engine does restart at a lower altitude; its serviceability is shot, whereby only an expensive teardown and overhaul will render it back to a serviceable state.

As I said earlier, volcanic ash plumes will not paint on Radar, therefore at night, when all visual cues have become shrouded by darkness, the only technology that will indicate its presence is either a laser or infra-red system. Usually however, it is the olfactory senses provided by the good old fashioned human nose, which will first sense the ash plumes proximity. In virtually all cases of aircraft that have flown through ash clouds, the crews have all reported that they smelled, or even saw smoke in their cockpits.

Now back to the AIM. As you have seen in this article, the existence and tracking of a volcanic plume is extremely difficult to be achieved by most aviation meteorological organizations. These groups rely heavily upon Pilot Reports (PIREPS) and therefore it is critical to air safety that if you encounter ash conditions in-flight, that you report them immediately. If operating in a known area of volcanic activity, make certain that you have read all NOTAMS and PIREPS that are available to you. Plan a reroute around all actual and forecasted ash clouds. Do not climb into ash. Instead reverse course and descend. Remember you are now in an emergency situation. If you encounter ash on the ground upon landing, do not use reverse thrust, and expect your traction and braking action to be minimal at best. If you are in the unusual position of being cleared to take-off on a runway contaminated by volcanic ash, it is imperative that you perform a long, slow and gentle running roll take-off, to not kick-up too much ash from your passage over it.

Do you still feel that it was a bad decision that was made recently over the volcanic ash contaminated skies of Europe? Hopefully your response is not just “no”, but “hell no” instead.


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