PARIS A research plane which could be taking ash samples to help airlines decide whether it is safe to fly was left grounded in rural England on Monday in a tug of war over its deployment, aviation industry officials said.
Airlines are putting pressure on UK authorities to release the BAE-146 aircraft, co-owned by Britain's weather office and a government research body, but have been told that it may not be available until later in the week, the officials said.
The delay came as Britain's Civil Aviation Authority warned of disruption by Tuesday from a cloud of ash spreading slowly southwards after Iceland's Grimsvotn volcano blew on Saturday.
Getting close to the ash to examine the type and density of particles is key to efforts to prevent a repeat of last year's crippling six-day shutdown of European airspace, which left over 10 million people struggling to cope with canceled flights.
European officials say they have learned the lessons from last year's volcanic ash crisis and have been discussing a UK-backed scheme that would place more control in the hands of airlines rather than forcing regulators to impose blanket bans.
But the system, which has not yet been accepted by all European countries, depends first on assessing the amount and type of ash in the atmosphere -- and only then allowing airlines to carry out their own assessments of the potential hazards.
Stuffed with sophisticated sensors, the BAE-146 research plane based at a university airstrip north of London is not the only means available to allow officials to gauge the risk from volcanic dust that can sandblast planes and clog their engines.
Others being deployed to avoid a new crisis include weather balloons, ground-based lasers and satellite imagery, backed up by reports from civil and military pilots.
These will supplement computer models that were blamed for sending the air industry blindfolded into last year's crisis.
The difficulty in scrambling Britain's so-called FAAM research plane, 48 hours after the latest eruption, highlights challenges facing regulators as they move from a bureaucratic system of national rules to rapid, better co-ordinated response.
"The FAAM aircraft is not available. It will become so in the very near future. At the moment the plan of action is to use a number of other avenues," a UK Meteorological Office spokesman said.
Direct Aviation, the Cranfield-based company which operates the aircraft north of London, declined to comment.
Germany's DLR aerospace center said it had not been asked to do its own research flights, but would be ready if asked.
The need for data is especially pronounced over the sea.
Hampered by an outdated jigsaw of national airspace boundaries, European officials know they need to find a better way of keeping Europe's crowded air corridors open.
Airlines complained bitterly last April when a bursting Icelandic volcano led to ban after ban closing Europe's skies.
Officials were reluctant to act any differently at the time because it was unknown how resistant aircraft engines would be.
Since then, consensus has formed around an ash threshold at which flying might be unsafe: 4 milligrams per cubic meter, which is seen as the first step in heading off disruption.
As research suggests engines may weather such levels with extra maintenance, regulators are wrestling with a new method that gives airlines power to choose whether to fly in any zone.
The stakes involved in perfecting a better crisis response were demonstrated in a simulation carried out just a month ago.
Airlines and regulators ran a scenario using the current evaluation system, then the proposed new discretionary method.
"This demonstrated clearly that with the technology now available, airlines are in a much better decision to make those operational decisions" said Brian Flynn, head of operations at European air traffic agency Eurocontrol.
"The simulation showed that approximately one third to one half of the flights canceled last year would have flown."
That might have spared airlines $800 million of an estimated $1.7 billion in lost revenues from the week-long crisis.
Germany however wants a different approach: bloc-wide safety rules applied across the European Union that clearly state when airspace should be closed, a transport ministry spokesman said.
The alternative system was due to get its first real-life test in Britain as ash seeped into Scottish airspace on Monday.
"The next few days will show who is willing to use the new scheme. We welcome it and think it's a good methodology," said Victoria Moores, spokeswoman for Europe's airlines lobby.
A crisis response cell created after last year's events held its first session on Monday to try to pull together a common view on ash regulation but remained divided, officials said.
Caught somewhat on the hop by the timing of the eruption, officials also raced to perfect a system for sharing information between airlines, but said coordination was working well.
(Additional reporting by Maria Sheahan; Editing by Louise Ireland)