Airliners and Volcanic Ash. By Owen Zupp.

 Volcanic Ash Cloud Cancels Flights

 (Image: Wiki)

As Mount Agung spews its ominous ash cloud into the sky above Bali, one's first thoughts must be with the local residents and the uncertainty that such eruptions bring to their region. For those wishing to travel to such holiday destinations, the eruption of volcanoes can lead to the cancellation of flights in the interest of passenger safety. So, how can a volcanic eruption potentially affect an airliner?

Volcanic ash poses a threat to aircraft on a number of levels.

Firstly, when a volcano erupts it spews its ash cloud high into the atmosphere where airliners operate. In turn, the strong winds aloft are able to carry the ash cloud great distances from the immediate area of the eruption. In 2011, the ash from Chile's Puyehue-Cordon Caulle volcano circled the globe to impact upon flights operating in Australia.

The volcanic ash is made up minuscule glass particles and pulverised rock which is harmful to aircraft engines. When drawn into a jet engine, the abrasive material can damage the compressor blades at the front of the engine and further downstream, become akin to molten glass in the hot combustion section. Ultimately, this molten liquid can solidify on the engine’s turbine blades. Together, this damage can play havoc with the airflow through the engine, causing it to stall. In the case of a British Airways flight in 1982, all four engines of a Boeing 747 lost power before the crew ultimately regained command of the engines and landed safely in Jakarta.

 

How Does Volcanic Ash Affect Jet Engines?

 (Image: Reddit)

As that crew also discovered, the abrasive effects were not limited to the engines and the windscreens became virtually opaque, making landing yet another challenge. In the cabin, the air conditioning system can become filled with the smell of sulphur and contaminants. Additionally, aircraft radars are designed for weather avoidance, they are not designed to detect volcanic ash. All in all, when volcanoes erupt, it is not an ideal time to fly.

One of the challenges facing airline operations is that the appearance of volcanic ash may present as normal clouds in the upper atmosphere. Furthermore, as mentioned, traditional airborne weather radar does not detect ash cloud, rendering it virtually invisible at night until it is entered. Interestingly, since the last post, in the video below, you can see that  NASA is developing new technology to map the three-dimensional structure of ash clouds. Stay tuned for further developments.


For now, airlines assess the risk to their aircraft and, more importantly, their precious passengers whenever volcanic eruptions take place. The grounding of flights is inconvenient to travellers and an expensive exercise for airlines, however, safety must always remain the first priority for all concerned.


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