The Spanish EU presidency said on Sunday it was possible that 50 percent of flights in Europe could operate on Monday following disruption caused by clouds of volcanic ash from Iceland.
Spain's Secretary of State for EU affairs Diego Lopez Garrido told reporters after a meeting at European aviation control agency Eurocontrol the ash cloud was moving slightly to the northeast, which could free up half of European air space.
"The forecast is that there will be half of flights possibly operating tomorrow. It will be difficult; that's why we have to coordinate," he said.
European Union Transport Commissioner Siim Kallas also told the same briefing he hoped that 50 percent of European airspace would be risk-free on Monday.
Kallas said the current situation was "not sustainable" and European authorities were working to find a solution that did not compromise safety.
"We cannot wait until the ash flows just disappear," he said.
Garrido said test flights had shown no damage to aircraft from the ash cloud.
"Lufthansa made 11 flights, KLM nine, Air France seven and the results show no impact in the area...no impact coming from the ash cloud," he said.
Kallas said a technical meeting of EU transport ministers on Monday afternoon would assess information from the test flights conducted in European countries.
"Based on new information from the test flights yesterday and today, we may be able to make a decision," he said. "All these new elements should be taken into account in the technical meeting."
He stressed the importance of a coordinated European response. "We have to deliver a more accurate European solution to open progressively European air space," he said.
Earlier, the main associations of European airports and airlines questioned the proportionality of restrictions that have closed much of European airspace and called for a reassessment.
The European Union on Sunday scheduled a special videoconference of its transport ministers, as a volcanic ash cloud from Iceland continued to wreak havoc on air traffic.
Barcelona on Sunday became the latest city to succumb to air traffic chaos as an Icelandic volcano continued to spew ash into Europe's skies.
Spanish authorities shut down the city's airport, along with 12 others in northern Spain. Among those affected by the shutdown were Israeli tourists instructed to make their way to Barcelona, from where flights were supposed to return them home.
Two El Al planes on their way across the Mediterranean were turned back as prevailing winds drove a huge cloud of volcanic debris toward southern Europe.
The EU transport ministers are to talk about the effects of the eruption of the volcano near the Eyjafjallajoekull glacier in southern Iceland.
The group will also discuss alternatives to air travel.
Meanwhile, France and Germany reopened several airports and conducted successful test flights on Sunday. Germany has opened six airports in five German cities for flights heading in an easterly direction and for planes coming from there until 1800 GMT, a spokeswoman for German air traffic controllers said on Sunday.
The airports are Berlin Tegel, Berlin Schoenefeld, Erfurt, Hamburg, Leipzig and Hanover.
"A gap in an easterly direction has appeared in the ash cloud," the spokeswoman said.
The French civil aviation authority said that several airports, including Toulouse, which had been due to close Sunday afternoon would now remain open until at least 1300 GMT on Monday, April 19.
The airports of Bordeaux and Marseille will reopen and will remain open until the same time, a spokeswoman said. They had been closed because of the spread of a cloud of volcanic ash that has disrupted air travel in Europe for four days.
Air France airline said that a first test flight by a plane from Paris to Toulouse had ended without problems on Sunday and further tests were continuing.
More than 200 flights in and out of Tel Aviv's Ben-Gurion airport have been canceled as a result of the eruption, with over 40,000 Israeli passengers affected, the Israel Airports Authority said.
Israel's Tourism Ministry said it was handling calls from thousands of tourists stranded in Israel and that it was assisting them in finding accomodation.
The ministry said Jerusalem and Tel Aviv municipalities will publish an information booklet for stranded travellers, to be distributed to hotels.
Air Canada on Sunday canceled a scheduled flight to Ben Gurion from Toronto - the first trans-Atlantic connection to Israel to be canceled since the Eyjafjallajokull volcano began erupting for the second time in a month on Wednesday.
The airline industry, already reeling from a punishing economic period, is facing at least $200 million in losses every day, according to the International Air Transport Association.
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