How dust puts planes in danger

By Stephen Beech via SWNS

Passenger aircraft are in danger of crashing due to engine wear caused by the accumulation of dust as they wait to land, warns new research.

Jets flying into one of the world's busiest airports are ingesting around 10 kilos (22 lbs) of dust per 1,000 flights - with most of it ingested while they circle before landing, say scientists.

Reading University researchers used 17 years of European Centre for Medium-Range Weather Forecasts (ECMWF) atmospheric data and data from the CALIPSO satellite to calculate the quantity of sand and dust swallowed by jet engines at 10 major international airports.

The airports, all located in desert regions or subject to seasonal dust storms, were Phoenix, USA; Canary Islands; Marrakesh, Morocco; Niamey, Niger; Dubai, United Arab Emirates; Delhi, India; Beijing, China; Hong Kong; Bangkok, Thailand; and Sydney, Australia.

The study, published in the journal Natural Hazards and Earth System Sciences , found that the largest dust doses were ingested at airports close to the Sahara desert, the Middle East and Northern India, when dry and hot conditions drive large dust storms.

Summer flights into Delhi topped the list, ingesting an average of 6.6 grams per arrival in the run-up to monsoon season, and 4.4 grams upon departure.

Delhi was followed by Dubai and Niamey at 4.3g and 4.7g per arrival respectively, while flights into Beijing swallowed 2.9g on average.

Study lead author Dr. Claire Ryder, of the University of Reading , said: "Dust and sand are dangerous to aircraft because dust melts to form glassy deposits on blades or hard mineral crusts inside engines.

"These crusts disrupt airflow and cause overheating, resulting in accelerated engine wear.

“Although the amount of dust ingested per flight is not huge, the amounts quickly add up.

"A plane consuming five grams of dust per arrival and departure will eat 10 kilos of dust over 1,000 flights.

"Planes will consume more dust when they are at lower altitudes waiting to land at, though this depends on the local weather conditions which affect the height of a dust plume in the atmosphere.

“Climate change may lead to a dustier world as temperatures rise and deserts expand, but we cannot say for sure - yet.

"Climate models do not currently provide a consensus on whether global warming will mean a dustier world, as dust emissions depend on a lot of factors, such as soil moisture, precipitation, surface wind patterns and vegetation cover."

The research team found that aircraft ingest more dust while they are performing holding patterns - the formation aircraft assume while pilots are waiting for permission to land.

The finding suggests that greater quantities of dust are consumed at low holding patterns of one kilometer (0.61 miles), where peak dust concentrations often occur.

Holding patterns of 10 to 15 minutes at a one-kilometer altitude can lead to more dust ingestion than during the take-off, climb and taxi phases of a flight.

For example, at Delhi airport during summer, holding at 1km altitude contributes 50% of total dust ingestion.

But by changing the holding pattern altitude away from the dusty layers, dust ingestion could be cut by 41%.

The researchers also suggest dust exposure could be reduced by changing flight schedules to avoid peak dust times.

They say shifting flights at Delhi and Dubai to night-time could reduce engine dust ingestion by more than 30%.

Dr. Ryder added: “Ongoing research at the University of Reading is working to improve the ability of climate models to predict dust emissions and transport through the atmosphere.”

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