pbr Hundreds of flights have been grounded as another volcanic ash cloud looms over Ireland and parts of Scotland.br ppbr Thousands of travellers faced further misery as a six hour no-fly zone was imposed across the Republic and Northern Ireland.br ppbr Airspace over the Outer Hebrides was also closed to operations last night. Airlines warned passengers not to travel to airports without checking on-line that their flight is departing.br ppbr Flights from continental Europe will not be impacted by the plume of ash from Iceland's volcano Eyjafjallajokull, which caused travel chaos when it forced the closure of much of Europe's airspace for almost a week last month.br ppbr The Irish Aviation Authority (IAA) and UK's Civil Aviation Authority (CAA) are monitoring the latest situation after it was predicted ash concentrations would exceed acceptable engine manufacturer tolerance levels.br ppbr Irish airspace will reopen at midday.