Passengers sleep on the floor in the main terminal at Edinburgh Airport, in Scotland


It looks like Grimsvotn will be back in the headlines today.

The spread of ash from the Icelandic volcano could force the cancellation of up to 500 commercial flights in Northern Ireland, Scotland and parts of Scandinavia according to the European air-traffic agency Eurocontrol on Tuesday.

252 flights have already been cancelled from Scotland down to Newcastle in northern England.  So far, flight cancellations have been the decision of individual airlines.

The ash plume is not expected to affect trans-Atlantic flights whose tracks are south of the projected path of the ash.  Consequently, it is unlikely to further affect U.S. President Barack Obama's visit to Europe.

According to the British Civil Aviation Authority, strong winds over Scotland are making it hard to predict the direction in which the ash will move.  However, air-traffic controllers predict that it will reach airports in Scotland, northern England and Northern Ireland on Tuesday afternoon.

This has led British Airways to suspend all flights for Tuesday morning between London and Scotland.  Dutch carrier KLM and budget airline Easyjet have also canceled flights to and from Scotland and northern England.  Though the airports remain open, experts expect that flights will be affected between 1200GMT and 1800GMT.

Dublin-based Ryanair was a harsh critic of the handling of last year's ash cloud from Iceland and called on air-traffic controllers to reopen airspace over Scotland.  The budget airline company successfully operated a verification flight to 12,500 meters in Scottish airspace on Tuesday.

There was no visible volcanic ash cloud or any other presence of volcanic ash and the post-flight inspection revealed no evidence of volcanic ash on the airframe, wings or engines, it said in a statement.  The absence of any volcanic ash in the atmosphere supports Ryanair's stated view that there is no safety threat to aircraft.

The widespread disruption from last year's Eyjafjallajokull volcano is still fresh on the minds of many European travelers.   The volcano erupted last April, forcing air-traffic controllers to ground commercial aircraft for six days due to safety concerns.  This cost airlines millions of euros in revenue.

The ash from this year's eruption is said to be heavier and thus falling to the ground more quickly.  Experts hope that this means a quick return to normalcy.

We are still looking at a very challenging week for passengers and for the airlines, the EU transport commissioner told a news conference, stressing that volcanic ash can still pose a safety risk to aviation.

Although we are partly dependent on the weather and the pattern of ash dispersion, we do not at this stage anticipate the widespread airspace closures and the prolonged disruption we saw last year, he said.

Grimsvotn, the creator of the recent disturbance, is an active volcano that lies at the heart of Iceland's biggest glacier in the south-east corner of the country.  This is its largest eruption in 100 years, blasting roughly 100 times more material per second into the atmosphere than was released from Eyjafjallajokull last year.  The event led Icelandic air-traffic control to shut Keflavik International Airport on Monday, the country's main hub.

The outlook for the rest of the week looks better.  Activity at the volcano has slowed and its ash plume had dropped overnight from its peak of 20 kilometers to between 3 and 5 kilometers in altitude, the Icelandic Meteorological Office said today.