ash and aviation safety
of volcanic ash near active volcanoes are an aviation safety hazard, especially
for night flights. Volcanic ash is hard and abrasive, and can quickly cause significant
wear to propellers and turbocompressor blades, and scratch cockpit windows, impairing
visibility. The ash contaminates fuel and water systems, can jam gears, and make
engines flameout. Its particles have a low melting point, so they melt in the
combustion chamber and the ceramic mass then sticks to turbine blades, fuel nozzles
and combustors, which can potentially lead to total engine failure. Ash can also
contaminate the cabin and damage avionics.
1991, the aviation industry decided to set up Volcanic Ash Advisory Centers (VAACs)
for liaison between meteorologists, volcanologists, and the aviation industry.
to 2010, aircraft engine manufacturers had not defined specific particle levels
above which they considered engines at risk. Airspace regulators took the general
approach that if ash concentration rose above zero, they considered airspace unsafe,
and consequently closed it.
costs of air travel disruption in Europe after the Icelanding volcanic eruption
in 2010 forced aircraft manufacturers to specify limits on how much ash they considered
acceptable for a jet engine to ingest without damage. In April, the UK CAA, in
conjunction with engine manufacturers, set the safe upper limit of ash density
at 2mg per cubic metre of air space.
May 2010, the CAA revised the safe limit upwards to 4 mg per cubic metre of air
further disruption this and other volcanic eruptions could cause, the CAA created
a new category of restricted airspace called a Time Limited Zone (or TLZ).
categorised as a TLZ is similar to airspace under severe weather conditions in
that restrictions should be of a short duration. However, a key difference with
TLZ airspace is that airlines must produce certificates of compliance for aircraft
entering these areas. Any airspace where ash density exceeds 4mg per cubic metre
is prohibited airspace.
Ash Clouds | booking