HELSINKI - Finnish fighter jets which flew through the volcanic dust covering much of Europe suffered damage and the air force warned Friday the cloud could have a significant impact on planes.

The air force F-18 Hornet jets were on training flights in northern Finland on Thursday morning, when airspace was still open, and the engines were later found to contain fine, volcanic ash dust.

"Based on the pictures, it was discovered that even short flights in ash dust may cause significant damage to an airplane's engine," the Finnish Defence Forces said in a statement.

Images taken inside one Hornet engine with a fibroscope camera indicated that the heat of the engine - around 1,000 degrees Celcius - had melted the ash inside the engine, blocking ventilation channels. "Blockages of ventilation channels caused by melting ash lead engine components to overheat and material to weaken," it said, adding this could fracture rotating engine parts.

In the worst case, the weakening of component materials could cause "parts to detach and the engine to be destroyed," it said.

The Hornets exposed to the dust from the eruption of a volcano in Iceland would be checked thoroughly, with "at least some" of the engines detached and sent for further studies and repair.

A growing question is "Are we over reacting - this suggests not. What would you do? Would you fly?

HT Ton Z

Consumers were warned that shops could start running low on supplies of fresh vegetables and fruit, and analysts said economic costs could spiral. Howard Archer, chief European economist at IHS Global Insight, said "the longer that the problem does persist, the more serious will be the economic repercussions". British and Irish scheduled airlines are losing up to £28m a day, with the total bill to European carriers hitting $200m, according to the International Air Transport Association.

One of the UK's biggest fresh fruit importers said business had ground to a halt. Anthony Pile, chairman of Blue Skies, said the company was losing £100,000 a day.

More than three-quarters of flights were lost yesterday across Europe, with barely 5,000 taking off or landing, the Eurocontrol air traffic agency said. This compares with 22,000 on a typical Saturday. Among the flights that did make it were three British Airways planes from New York which scraped into Glasgow and Prestwick airports in Scotland.

Around Europe, 73 transatlantic flights landed yesterday morning, less than a third of the 300 that would normally arrive. The situation deteriorated from Friday, when 10,400 flights out made it out of the normal 28,000.

Met Office forecasters said it would take a prolonged change of wind direction for the situation to improve. "The UK and much of Europe is under the influence of high pressure, which means winds are relatively light and the dispersal of cloud is slow. We don't expect a great deal of change over the next few days," Mr Leith said.

Several airlines are challenging the ban - KLM, Air France and Lufthansa are running tests - is the ban too restrictive?

With airports closed until Monday, the pressure is building for a work around.

Iceland volcano eruption causes more air travel headaches but trains move the stranded travelers in Europe in another example of how a viable passenger rail service can provide transportation in a natural disaster.

The Eurostar trains quickly sold out when the volcano closed European airspace this week, but the secondary trains were able to help keep passengers moving towards their destinations.

The extensive network of intercity trains in Europe were able to step up and help when airlines were grounded. Do we have this capability in most of the United States? No, unfortunately most of the US is not covered by adequate train transportation to be helpful.

The exceptions in the Northeast Corridor (NEC) and California not withstanding many locations with Amtrak service only see one train in each direction a day. This of course, would not be enough to replace the thousands of daily short and mid-distance flights.

After 9/11/01, Amtrak was able to help move stranded passengers, but to do this it has to have trains scheduled and available.

Now is the time to expand AMTRAK so that it can help when it is needed in a Natural or other disaster.

We have all our eggs in the flight bucket - it would also be great to invest in rail to help the economy too