(Bloomberg) — Airlines forced to tear up timetables after ashspewed from an Icelandic volcano in 2010 face less disruption froma repeat because they've adopted a more scientific process toidentify the most dangerous skies.

The Chart of the Day shows the percentage of flights canceledand number of passengers grounded four years ago, when a cloud fromthe Eyjafjallajokull volcano forced carriers to scrap more than100,000 flights, costing $1.7 billion in lost revenue. While 80% oftrips were idled on the worst day, a similar event now would bringsignificantly fewer cancellations, according to airspace managerEurocontrol.

“There has been a move towards a more harmonized approach whichrecognizes that decisions to perform flights in airbornecontamination such as ash or sand should be made by airlines, basedon conclusions of their safety risk assessment,” the Brussels-basedorganization said in a statement. “This approach significantlyreduces the number of flights that would have to be canceled in theevent of another ash crisis.”

After the events of 2010, repeated on a smaller scale the nextyear, Eurocontrol began annual ash-crisis exercises and developedan interactive tool to map dust-concentration data from volcanicresearch centers in London and Toulouse, France, rather thanrelying on predictions based on weather forecasts.

Seismic activity around Iceland's Bardarbunga volcano hasprompted authorities to lift the risk-assessment estimate to“orange,” the second-highest level. Air France-KLM Group, Delta AirLines Inc. and Deutsche Lufthansa AG are among carriers on alertfor ash, which is a menace to jets because the glass-like particlescan damage engines.

In the event of a Bardarbunga eruption, EasyJet Plc plans totest ash-detectors it's developing with partners including AirbusGroup NV and Nicarnica Aviation. The technology available todaywould have resulted in the closure of less than 3 percent of theairspace affected in 2010, spokesman Paul Moore said.

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