Volcanic ash in jet engines

There are over 500 active volcanoes in the world and on average twelve volcano eruptions a year. In 2010 the Eyjafjallajökull eruption in Iceland affected not only the aviation industry but also the entire global economy. The ash cloud almost entirely paralysed air traffic over Europe in some of the most congested airspace in the world.

Since the danger posed to airplanes by volcanic clouds was not well understood at that time, the guidance used worldwide from the International Civil Aviation Organisation (ICAO) was to avoid any amount of ash. The guidance actually stated “In case of volcanic ash regardless of ash concentration: Avoid. Avoid. Avoid.” Since it was no option to fly around the ash clouds, more than 100,000 commercial flights had to be cancelled during the eruption phase.

The loss from the Eyjafjallajökull eruption, US$ 1.8bn for the airlines alone, according to IATA estimates, was substantial – and uninsured. With business interruption, aviation insurance policies usually only come into effect when preceded by damage to the insured object. This was not the case here.

Even five years later, virtually no airline is covered for the financial consequences due to non-damage business interruptions such as revenue losses and the cost of providing care to passengers.

Hit hard financially after the Iceland eruption, aircraft operators demanded to decide by themselves where and when to fly based on their own safety risk assessment. In response the aviation rules got cut back and ash contamination was divided into different contamination zones. Since mid 2010 continuously updated volcanic ash charts identify and forecast three specific ash contamination levels in the air space; coloured in cyan (low contamination), grey (medium contamination) and red (high contamination).

Airlines are now permitted to fly in the zones of low contamination. This resulted in smaller areas being closed, and for shorter lengths of time. The zonation scheme gives the impression that flying in low contamination is “safe” – but not necessarily for the jet engines. 

Volcanic ash is a product of explosive volcanic eruptions; the ash contains more than 50% silica particles, an extremely hard and abrasive material. Since the melting point of the particles is well below the core temperatures in jet engines, there is a high potential for ingested ash to melt and to resolidify within the turbines. The results could be a rapidly increased static burner and compressor discharge pressure, which might lead in most severe cases to engine surge and a loss of thrust.

Volcanic ash accumulates continuously within jet engines as they fly through ash clouds. Thus a long flight through a low contamination zone may do more damage than a short flight in a high contamination zone. Since the airline operator is responsible for approving flights through ash clouds, and not the authorities as it used to be, such risks need to be evaluated closely in the risk management of airlines.

The problem with accumulated ash in aircraft engines is the high uncertainties of the jet engines´ tolerance to ash, which varies tremendously by engine and is not easy to measure without pulling the engine apart – something that is simply impossible for operators with prescheduled flights.

Should volcanic ash from a single incident result in the loss of an aircraft, an airline would be covered as normal under their traditional hull and liability policy. However, physical damage from prolonged or cumulative exposure to volcanic ash conditions may not be covered, as it would likely be deemed just as “wear and tear”. Aviation airlines would have to bear the repair costs themselves.

Arising from the mandatory grounding of aircrafts, flight disruptions or restrictions due to volcanic ash cloud as well as related repair costs, would also not be covered under a traditional hull and liability policy. Although in 2015 alone there had been several eruptions in Chile, Japan, Bali and Russia, which resulted in only minor disruptions, the next large event might be closer than many operators are financially prepared for. Munich Re is offering  customized coverage solutions for corporates seeking to also insure against ”non-damage” business interruption losses.

In 2010 a NASA-led research program was initiated, supported by engine manufacturers such Boeing, Rolls Royce, General Electric and Pratt & Whitney. Injection of ash into engine tests have been done and the test result are to be published in early 2016. ICAO, amongst others will be able to look at the data for to understand more about to how to fly safely and whether the current guidance is too restrictive or not.