It's not a good day to fly to Europe. The drifting ash cloud from the Eyjafjallajokull volcano that erupted in Iceland earlier this week is still causing massive flight delays that could get worse by the end of Friday, with 17,000 flights likely to be canceled across the continent. Poland considered, and then decided against, delaying the funeral for its president Sunday because some world leaders could be unable to fly to Warsaw. Normally, 28,000 flights pass through European Airspace, but only 20,334 did on Thursday and Friday that total is expected to drop to 11,000, creating the worst international travel interruption since the September 11 attacks. Airspace in Belgium, the Netherlands, Denmark, Sweden, Norway, Finland, Estonia, and parts of Germany, France, and Poland, has been affected. The cloud is a significant danger to flights, as small particles in it can cause engines to seize. Currently, it's drifting east and south-east, according to Eurocontrol, which said it expected air traffic disruptions to continue for at least another day.