London, April 18: A sprawling cloud of volcanic ash paralysed air travel across much of Europe for a fourth day on Sunday, but test flights with empty airliners showed no sign of damage and offered some hope of respite. European Union transport ministers plan to examine the test flights results on Monday and consider if airspace might be reopened despite ash from an Icelandic volcano.

Volcanic ash is abrasive and can strip off vital aerodynamic surfaces and paralyse an aircraft engine. Aircraft avionics and electronics, as well as windshields, can also be damaged.
Dutch airline KLM said inspection of an airliner after a test flight showed no damage to engines or evidence of dangerous ash concentrations. Germany’s Lufthansa also reported problem-free test flights, while Italian and French carriers announced they would fly empty airliners on Sunday.
The Association of Dutch Pilots said it believed, along with sister organisations, that a partial resumption of flights was possible despite the continuing eruption spewing black ash high over Europe.
Through Sunday, a clampdown held across much of Europe, posing a growing problem for businesses — especially airlines, estimated to be losing $200 million a day — and for thousands of travellers stranded worldwide. The European aviation agency Eurocontrol said only 4,000 flights were expected in European airspace on Sunday, compared with 24,000 normally. It said a total of 63,000 flights had been cancelled in European airspace since Thursday.
Many countries, including Austria, Britain, France, Denmark and Sweden, closed their airspace into Monday. Russian airports remained open, routing planes to North America over the North Pole to avoid the cloud. Weather experts said wind patterns meant it was not likely to move far until later in the week.
The plume was expected to become more concentrated Tuesday into Wednesday, posing a greater threat to air travel, but narrowing to affect a smaller area. A shift in jet stream winds from Thursday could purge the plume out of most of Europe.— Reuters

Ralph Gowling