VOLCANOES AND AVIATION SAFETY
In the recent past, a number of aircrafts have had terrible encounters with suspended
volcanic substances from the explosions from the active volcanic mountains. When the volcanic
ash suspends in the air, it gets in the way of flights leading to damages either on the plane or run
way. There are different types of volcanic ash depending on the composition and level at which
they will be hauled.
There is dormant volcanic ash that mainly has water vapour and gas and few or no rock
particles. These goes up to only 6,000metres above ground level and hauled ten miles or less.
They have least effect on aircrafts. Eruption columns are basically pillars of ash that are about
12,000 metres to 30,000 metres high. They are composed of rocks of several diameters, dense
air and gas. Their effect is also not as hard felt. The most damaging ash is the drifting ash cloud
which has fine broken rocks and gas. These move like a cloud and might be carried along by the
jet stream which makes it difficult to distinguish between normal clouds and the ash cloud.it may
also go till 1,000miles.1
Aircraft damages may vary from exterior parts to the inside. Most of the volcanic ash
contains rock fragments that may easily abrade planes ‘structural materials. It results in wearing
off of paint used and plastics used to protect edges of the wings. Sharp objects may break or dent
glass windows consequently huge bills on repairing.
Engine failure is probed by ash deposits in turbines and sulphur components that hinder fuel
mixing. When a high speed blast of ash enters the engine, it may erode sharp edges of the
compressor slowing it down reducing its efficiency in cycling the air. This same air is supplied to
cabin for respiration. A dioxide of sulphur (SO2) in increment takes all the oxygen available
reducing it to low levels. If not tackled immediately, it is lethal if ingested by passengers. (slow
poison) [Rose,1991]. Molten glass maybe formed in the combustion chamber if
ash melts there. If again it solidifies, it may result in blocking turbines hence stalling engine and
reducing airflow1. Clogging of the engine makes it susceptible to a flame-out, en route.
Another huge disruption in the stratosphere is observed when sulphur dioxide is left suspended
in the atmosphere after a large eruption. The aerosols tend to mix up with water vapour droplets
in the clouds forming sulphuric acid. Sulphuric acid may subject the aircrafts’ skins and
windows to micro-cracks especially the acrylic windows. A good example is the Mexico’s El
Chichon(1992)[Rogers J.T., April-June 1984] and Pinnatubo(1991)[PVOT,1991] eruptions
whose effects of sulphur are still abundant in the rainfall over the specific areas. Repeated
exposure to the ash clouds also may lead to long term damages on the air frames and skins.
Volcanic ash is not only consequential for in-flight aircrafts, but also when on the ground.
Rain and ash mixed cause a slippery substance on run ways and taxiways, leading to difficulties
in landing, take-offs or loading.
Once affected, an aircraft can be cleaned though with thoroughness and extreme care. This is
because volcanic ash and water form an extremely slurry substance hard to remove. In
Kagoshima airport in Japan they have introduced a simple yet efficient method of washing of ash
due to their regularly experienced ash falls. The method includes blowing off the ash, then
vacuuming the engines to remove residue and finally washing with pure water to remove fine
particles. On runways, the Cubi Naval airport has successfully cleaned ash falls depending on the
thickness whereby, the less thicker ones water is used if its adequate and availability of drainage
space. For thicker ones, vacuuming with large equipment is first carried out before washing with
water.1
Nevertheless, it has been proven that avoidance of ash clouds is the best method of ensuring
aviation safety. This includes proper clear communications between ground controllers and the
flying crew. Pilots must be alerted on temperature changes and altitudes which they are using to
fly so as to avoid plying those with great eruptive occurrences. Meteorologists and dispatchers as
well should be on the know concerning different regions and flights to warn if any, oncoming
ash falls. Relative survey of the atmosphere should be done prior to any aircraft scheduled to
take-off. This has been enabled by satellite observations and instruments installed on both aboard
and on ground that detect the eruptions or track volcanic ash. The three essential points in
avoiding inadvertently flying into volcanic ash are communications from ground controllers,
reports on expected and recent eruptions and observations of the atmosphere. There has also
been a suggestion for aircrafts to carry alternate fuel on-board or plan for alternate routes, all in a
bid to avoid volcanic plumes.
Various adjacent regions should also work together to coordinate flights because the ash
clouds are not stagnated and may travel across different regions, disrupting air travel.
References:
1Casadevall
1. Casadevall T. J. The Eruption of Redoubt Volcano, Alaska ,1989-1990
2.PVOT [Pinnatubo Volcano Observatory Team] Lessons from a Major Eruption: Mount Pinnatubo, Phillipines v.72 ,1991
3. Rogers J.T. Results Of El Chichon, April-June 1984.
4. Rose W. I. interaction Of Aircraft and Explosive Eruption Clouds: AVolcanologist’s Perspective v.25 ,1987.
