Niki Lauda has appealed to passengers stranded at European airports because of the eruption of an Icelandic volcano to remain patient.The three-time Formula One champion who now runs his own budget carrier FlyNiki said in a TV interview last night (Thurs): “Volcano ashes can ground a plane. The situation is extremely dangerous, and cancelling flights is the only way to avoid a disaster.”Lauda, who flies his airlines planes himself on a permanent basis, stressed: “Planes simply cannot fly through ash clouds.”The former Lauda Air boss explained crystals and small rocks the massive volcanic ash cloud would have the “effect of sand paper”, while the ash itself clogs planes lines and electric connections. He added there was no technical solution as of now.”Airlines suffer insane losses because of the many cancellations, but it would be just stupid to ignore the existing dangers. Passengers should stay patient,” Lauda said.Hundreds of thousands of passengers are stranded at several European airports due to the unexpected lockdown. There has never been a comparable incident in Europe before, aviation experts pointed out.The eruption of volcano Eyjafjallajokull, also known as Eyjafjoll, could cause disruptions for around six months a result of contaminated air drifting over northern Europe, some experts have claimed.The dust can cause airplane engines to fail and would diminish pilots viewing conditions, while health experts appeal to people suffering from asthma and breathing difficulties to stay indoors.European aviation agency Eurocontrol said disruptions of the continents air traffic were expected to continue at least until tomorrow, depending on whether the volcano continues to emit dust.Northern and Central Europe are currently mostly affected by the disruptions. Dozens of intercontinental flights set to start from London-Heathrow and other major airports have been cancelled after the volcano erupted on Wednesday.Austrian aviation officials meanwhile decided to shut down air traffic in the northern part of the country from 8pm tonight. Markus Pohanka, a spokesman for the countrys aviation authority, said: “The safety of the passengers is our top priority.”Pohanka explained around 4,000 planes were travelling over Austria everyday. “Around 1,000 passenger planes start at Vienna International Airport [VIA] everyday, and we expect one in ten to be cancelled today,” he added.Pohanka explained it was unable to determine how long the Austrian airspace would remain closed for traffic since reliable forecasts can only be made for the next 12 hours.He said VIA and the airports of Salzburg and Linz would be shut down at 8pm, while the plan is to keep the airports of the southern cities of Graz and Klagenfurt open as long as possible considering the circumstances and passenger safety.