The densest parts of an ash cloud from the Grimsvotn volcano are expected to exceed a new safety threshold used by airlines and could disrupt travel at Scotland's busiest airports in Edinburgh and Glasgow. Loganair, a regional carrier based at Glasgow airport, cancelled 36 flights. "The volcanic ash forecasts issued by the Met Office . . . indicate that a high density of ash will be present in large parts of Scottish airspace," said the airline.
The air safety watchdog for British airlines and airports, the Civil Aviation Authority, said particles from Grimsvotn could affect transatlantic journeys by reaching western England on Thursday or Friday, depending on wind direction.
High winds had already caused disruption in Scotland and northern England yesterday, with 100mph winds disrupting motorists, rail users and homeowners in Scotland, causing mass cancellations of rail services, and power cuts.
Eastbound traffic on the M62 between Leeds and Manchester was brought to a standstill, while three racing yachts were rescued after high seas disrupted an event between Whitby and Scarborough.
The high winds are expected to affect ash cloud forecasts. The Met Office warned of difficulties in tracking the cloud's progress because of erratic shifts in wind direction. If airspace in western England, Ireland and the Atlantic is affected by the smoke plume, US-bound flights from Heathrow could see delays later this week as planes are diverted around the most dense parts of the cloud. However, the CAA said it was confident that a new Europe-wide safety regime introduced after the Eyjafjallajokull eruption last year would reduce disruption significantly and avoid the continental shutdown that stranded millions. Under the new operating procedures, it is understood that the effect of last year's plume on commercial routes would have been reduced by 75%.
Andrew Haines, the CAA's chief executive, said: "Our number-one priority is to ensure the safety of people both on board aircraft and on the ground. We can't rule out disruption, but the new arrangements that have been put in place since last year's ash cloud mean the aviation sector is better prepared and will help to reduce any disruption in the event that volcanic ash affects UK airspace."
Under previous guidelines, aircraft were summarily grounded if there was any volcanic ash in the air. Now, airlines can fly through ash plumes if they can demonstrate that their fleets can handle medium or high-level densities of ash.
The Met Office's volcanic ash advisory centre will identify the density and location of the cloud, aided by satellite images, weather balloons and a radar specially installed in Iceland last year. Once those zones are relayed to airlines, they will need to prove that they can fly through them by producing "safety cases" that will include information from aircraft and engine manufacturers on the airline's tolerance to volcanic ash.
A CAA spokesman said all major UK airlines had already prepared for medium-density ash clouds. "We are in a much better position than last time," he said. "Safety will still be paramount, but we will be able to drastically reduce disruption compared to last time, provided there is not a huge amount of high-density ash." However, jets would still have to divert around high-density clouds, causing delays on some routes.
BAA, owner of Heathrow, Stansted, Edinburgh, Glasgow and Aberdeen airports, has convened a crisis team to prepare for a cut in flights, as airlines and airports await a briefing from Eurocontrol and the UK air traffic controller, Nats.
The Grimsvotn volcano began erupting at the weekend, causing flight cancellations at Keflavik airport after it sent a plume of ash, smoke and steam 12 miles into the air.
A satellite image shows ash and smoke drifting out to sea from the south coast of Iceland Photograph: AFP/Eumetsat/Metop