But flights remained grounded in large parts of the continent as authorities across Europe said there was no end in sight to the plume spewing out of a volcano in Iceland that they insist is dangerous to planes.
Millions of passengers have had plans foiled or delayed because of a ban on air travel that has gradually expanded over large swaths of Europe since Thursday.
The aviation 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.
‘No irregularities’
KLM, a subsidiary of Air France, said it carried out the test flight above Dutch airspace on Saturday. It said initial inspections showed no damage or irregularities from the ash in the air.
The airline says it now plans to return seven airplanes without passengers to Amsterdam from Duesseldorf on Sunday.
“We hope to receive permission as soon as possible after that to start up our operation and to transport our passengers to their destinations,” said chief executive Peter Hartman, who was aboard Saturday’s flight.
Kyla Evans, spokeswoman for the European air traffic control agency Eurocontrol, said it was up to national aviation authorities to decide whether to open up their airspace.
Scientists say that because the volcano is situated below a glacial ice cap, magma is being cooled quickly, causing explosions and plumes of grit that can be catastrophic to plane engines, depending on prevailing winds.
In Saturday’s test flight, a KLM Boeing 737, flew up to 41,000 feet, the maximum altitude at which the aircraft is certified to fly. Also on Saturday, Germany’s Lufthansa flew 10 empty long-haul planes to Frankfurt from Munich at low altitude under so-called visual flight rules, in which pilots don’t have to rely on their instruments.
The Lufthansa planes flew at various levels between 3,000 and 8,000 metres, spokesman Wolfgang Weber said.
He stressed that the flights were not tests, and were merely intended to get the planes in the right place at the Frankfurt hub for when restrictions are lifted. He said Lufthansa didn’t plan any more such transfer flights on Sunday.
The Swiss Federal Office of Civil Aviation began allowing flights on Saturday above Swiss air space as long as the aircraft were at least at 36,000 feet. It also allowed flights at lower altitudes under visual flight rules, aimed at small, private aircraft.
Germany extended closure of its airports through 1800GMT on Sunday and Britain until 0000 GMT, while the Dutch Transport Ministry said national airspace will remain closed to passenger traffic until at least 1200GMT on Sunday.
Airspace remained closed in Denmark, Finland and most parts of Sweden on Sunday. In Norway, authorities lifted air travel restrictions in the central part of the country, but kept airspace closed in other parts of the country, including the capital, Oslo.
