FRANKFURT Two German airlines on Sunday criticized aviation authorities for not taking more account of test flights carried out to assess the safety of flying through a volcanic ash cloud hovering over Europe.
"We are amazed that the results of the test flights done by (main carrier) Lufthansa and Air Berlin have not had any bearing on the decision-making of the air safety authorities," Air Berlin Chief Executive Joachim Hunold said in a statement.
Air Berlin is Germany's second biggest airline after Lufthansa.
European airspace has been restricted for up to four days, costing airlines millions of euros, after a volcano erupted in Iceland.
Air Berlin said in a statement it carried out three test flights at low altitude and was offering to do more. It said it was lacking guidance from the federal transport ministry and called for better cooperation between air carriers and the authorities.
"We offer -- as does Lufthansa -- to carry out more such flights to gain valid insights."
Lufthansa carried out test flights by 10 aircraft on Saturday and said post-flight inspections showed no impact on the planes, while Dutch airline KLM also said tests by aircraft had revealed no engine damage or other problems.
Air Berlin extended its flight cancellations until at least 8 p.m. EDT (2400 GMT) Sunday.
Hunold was also quoted in a newspaper as complaining about the air travel restrictions.
"The closure of the air space happened purely because of the data of a computer simulation at the Volcanic Ash Advisory Center in London," he told the mass circulation Bild am Sonntag (BamS) paper.
Referring to the same point, a spokesman for Lufthansa said it was "scandalous" that the closure was triggered by only one source as it was causing massive revenue losses.
"We reserve the right to ask the question who is liable here, who will pay for the (financial) damage," he told Reuters.
He put the losses from the grounded fleet at 25 million euros a day at least.
(Reporting by Vera Eckert and Martin Zwiebelberg; Editing by Charles Dick)