Airlines attacked aviation authorities yesterday, demanding a new approach that would allow them to fly more planes through volcanic ash.
British Airways, Ryanair and Thomson Airways all urged a revamp of the rules on no-fly zones after hundreds of flights were grounded in the morning and then allowed to resume in the afternoon. Winds are predicted to blow the ash cloud away from the UK this week, but further disruption is possible today as airlines seek to clear their backlog of services.
Geologists have warned that the ash from Iceland's Eyjafjallajokull volcano could disrupt flights for months and that other volcanoes, such as Katla, also on Iceland, could cause bigger problems in years to come.
Under the present regulatory system, the National Air Traffic Service (Nats) announces bans following Met Office forecasts on the location of the ash and advice from planemakers about the amount that can safely enter engines.
Michael O'Leary, the chief executive of Ryanair, called for an end to the Met Office's volcano concentration charts used to set the bans. He said: "Airlines have known for some weeks now that there has been little evidence of any volcanic ash in the atmosphere over Ireland, the UK or Continental Europe.
"The fact that Heathrow and Gatwick airports have reopened, despite the fact that the charts shows this imaginary black plume directly over these major London airports, shows that the charts have no credibility.
"It is frankly ridiculous that the flight plans of millions of passengers across Europe are being disrupted on a daily basis by an outdated, inappropriate and imaginary computer-generated model and it is time these charts were done away with."
Chris Browne, managing director of Thomson Airways, said that if the ash clouds continued, more accurate modelling was needed and it was "vital that we understand the tolerance levels for aircraft and engines in particular".
Willie Walsh, chief executive of British Airways, complained the bans were "a gross over-reaction to a very minor risk". He said: "I am very concerned that we have decisions on opening and closing of airports based on a theoretical model."
The Met Office rejected the criticism, saying that its charts were "continually looked at and updated". They were based on satellite pictures and ground-based laser observations, a spokesman said. He added: "Clearly there was some ash that was out there but it was in low levels in some parts of the UK. It's a tried and tested model."
Nats said UK airspace would be clear until 1am today but a no-fly zone would remain in force over parts of the North Sea, which could restrict helicopter flights. Yesterday it ruled the volcanic ash posed a danger to most of the UK, but lifted restrictions at Heathrow and Gatwick by about 11am and over all of mainland Britain by 1pm. Restrictions remained in force over the Scottish Islands.