'Ash Wednesday' volcano chaos may last until weekend

National Air Traffic Control Services (Nats) last night extended its closure of British airspace to at least 1pm today.

Ryanair, Flybe and Loganair – which operates Highlands and Islands services – were among carriers which had already cancelled all flights until at least 1pm. Flybe has also cancelled some 30 later flights.

Ministers said there was no sign of a change in the direction of the wind blowing the cloud south from Iceland. It contains tiny particles which could knock out aircraft engines and hit visibility from cockpit windscreens.

Emergency officials in Iceland yesterday evacuated hundreds of people as the danger of flash flooding hit the volcano area.

First Minister Alex Salmond said the ash could remain over the UK into the weekend, but there were contingency plans "to keep the population and essential air travel, moving".

Passenger flights at all Scottish airports were cancelled from 2am yesterday, with one aircraft from Toronto given special permission to land at Glasgow airport because it had taken off before the restrictions were imposed.

Nearly 50,000 passengers were affected at Edinburgh and Glasgow airports alone, with more than 500 flights cancelled.

The Nats restrictions – which only cover "controlled" airspace under air traffic control – were later extended to the whole of the UK from noon. Heathrow airport in London, the world's busiest international hub with 180,000 passengers a day, was among those brought to a standstill.

The ash cloud, spewing from an eruption on Wednesday, has caused more UK disruption than the aftermath of the September 2001 terrorist attacks in the United States, when only London-area flights were grounded.

All offshore helicopter flights were grounded for the first time in the history of the North Sea oil and gas industry yesterday.

Aberdeen, Europe's largest heliport, was hardest hit by the mandatory grounding of chopper operations as hundreds of oil workers were left either stranded on offshore installations or on the mainland because of the cancellation of crew change flights. Offshore flights were also suspended at Scatsta on Shetland.

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The ash, from the Icelandic mountain Eyjaffjalljokull, also caused airport closures across northern Europe including France, Sweden, Finland, Denmark and Holland. However, medical flights in Scotland continued, with the Scottish Ambulance Service airlifting a patient from Campbeltown to the Royal Alexandra Hospital in Paisley, and flying two emergency missions to Banff and Langholm.

Air ambulances are permitted to continue flying below 5,000ft under visual flight rules.

The Loch Lomond Seaplanes service between Glasgow and Oban was among the few unaffected commercial flights, because of its low altitude and not needing airport runways.

The impact of the dust has yet to be confirmed. The Met Office said dust and smells have been detected in Orkney and Shetland. A spokesman said last night: "We are liaising with Health Protection Scotland. Dust has been collected at Lerwick and is currently being analysed."

Finance secretary John Swinney said: "The analysis that we have of emissions from volcanic eruptions is that the ash is not poisonous and has the potential only to irritate those who may suffer from skin conditions or asthmatic conditions."

Einar Kjartansson, a geophysicist at the Icelandic Meteorological Office, said: "It is likely that the production of ash will continue at a comparable level for some days or weeks. But where it disrupts travel, it depends how the wind carries the ash."

Nats denied it had been over cautious in imposing the restrictions. A spokeswoman said: "We certainly do not think we have overreacted. Safety is our main priority and volcanic ash is a serious threat to aircraft.

"No-one can remember a time before when controlled airspace has been closed in the UK. This is certainly one of the most significant instances of flight restrictions in living memory."

Train operators laid on extra services, including Virgin on the Glasgow-London line and East Coast between Edinburgh and London. National Express ran additional long-distance coaches.

The European Commission said passengers could claim refunds for cancelled flights but not compensation.

Aviation experts said aircraft encountering a volcanic dust cloud was like hitting flying glass. The particles may be too small to see but they can be sucked into engines, causing them to fail.

They can also leave pilots flying blind by sandblasting cockpit windscreens.

Tiny fragments of glass in volcanic clouds melt after being sucked into aircraft engines, clogging them up. Hard ash particles can also damage an engine's fan blades, and may cause electrical systems to short-circuit.

A British Airways Boeing 747 lost power in all four engines when it flew into an ash cloud from Mount Galunggung in Java, Indonesia, in 1982. It glided down to within a few thousand feet of the ground before the engines could be restarted.

This led to procedures being changed. Rather than increase power, which can make things worse, pilots now descend below the ash cloud, with the inrush of clean air usually enough to unclog engines.

Four scientists took off from Oxford yesterday to fly into the ash cloud to take samples.

They were gathering data which could reveal important information about the environmental impact of the eruption.

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