New Delhi: Dense clouds of nearly undetectable ice crystals could be the reason behind plane crashes that have caused hundreds of deaths. The fatal "flour grain-sized" ice particles are formed at high altitudes, and can stick to plane engines causing a loss of power.
A report in New Scientist says that they can affect planes at altitudes up to 35,000 feet higher than traditional icing that is linked to liquid water.
The dangerous ice crystals are being called an "invisible killer" because they can't be seen by pilots or radars, and currently no commercial sensors or defenses can detect the icing or protect against its harmful effects.
Evidence was found revealing that these ice particles were the reason behind the crash of Air France Flight 447 into the Atlantic Ocean, which killed 228 people.
If that was the case, then the airliner might have flown over a band of thunderstorms shortly after leaving Rio de Janeiro. It's though that ice crystals caused an obstruction in the vital speed sensor, contributing to confusion that caused the pilots to think they were losing altitude.
The plane sharply angled upwards due to the crystals causing it to stall and crash. The chilly bane named "hot ice" has been blamed by NASA for over 200 power loss incidents in the last 20 years.
Most worryingly, the report suggests things might be getting worse. Rolls Royce are concerned that increasing frequency of extreme weather events caused by climate change could make the dangerous crystals more common, increasing the risk to air passengers.
How do ice crystals make a plane crash?
The daunting ice crystal clouds are known to be generated by deep convective thunderstorms. These systems suck up warm moist air from lower down, which cools forming water droplets.
These droplets then freeze and travel at the top of the system as ice clouds. These crystals are only 40 micrometers in diameter, which is about the size of a grain of flour.
That's too small to be seen by aircraft radar or by the pilots in the cockpit. Aircraft manufacturer Boeing's website says that crystal icing is thought to be the result of the tiny ice particles melting on hot engine surfaces, causing a "water film" to which other ice crystals can accumulate on.
The icy build up can stop an engine working by causing it to stall, extinguishing its flame or by damaging the engines blades when they are hit by lumps of accumulated ice breaking free.
This mechanism is actually quite similar to the mechanism by which volcanic ash clouds can cause jet engine sudden power loss. The ice can also block vital sensors, such as the "pitot tube", which caused the crash of flight 447.
Currently, there are no commercially available sensors which can detect the crystals or their accumulation in unwanted places.
Redesigning engines to avoid the "accumulation" of ice might have to happen, though aerospace engineers think that will take at least 20 years.
Many agencies are working hard to solve the problem, but lots more work needs to be done before experts can accurately predict when and where the icy danger will strike.
Experts fear that the crystalline menace will become more common as a result of climate change. “The weather systems that cause the ice crystals will be more vigorous and more frequent in the warmer, moister world predicted by climate change” says Sue Gray, a meteorologist at the University of Reading.
Whatever happens, it will remain difficult to tell when the scary-snow has struck, because by the time a plane reaches the ground all evidence of the ice blockages is likely to have melted.
