Air passengers faced more disruption yesterday as the Icelandic volcanic ash cloud caused further delays and cancellations.
Budget airline Ryanair said it has cancelled dozens of flights to and from destinations in Spain, Portugal and the Canary Islands.
And rival carrier easyJet also warned there could be more disruption to flights to and from France, Spain, Portugal and Gibraltar.
BAA said all of its airports were open and operating normal schedules, but warned of delays to transatlantic services and cancellations by airlines.
A flight between Faro, Portugal and Belfast International was cancelled yesterday, as were flights between Belfast and the Spanish destinations Lanzarote, Malaga and Murcia.
Latest meteorological charts showed the ash cloud extending across the Atlantic into Spain and Portugal, and further east over France.
A Ryanair spokesman said the Belfast jet forced into a dramatic turnback on Monday would not have flown in concentrations of ash above recommended levels.
Aircraft were banned from airspace for around six days last month but guidelines permit flights where the concentration of ash is at or less than 0.002g per cubic metre of air.
Airports and airlines continued to urge passengers to check the latest information before travelling to their airport.
British Airways and Virgin Atlantic were among the carriers whose passengers suffered long delays to transatlantic services yesterday.
Some London-bound flights departing from the USA were arriving up to three hours late at Heathrow and Gatwick Airports.
Among services cancelled by easyJet yesterday were Barcelona and Madrid, and Faro in Portugal.
EasyJet said the vast majority of its flights were operating normally, but advised passengers travelling to and from Tenerife, Madrid, Faro, and Funchal in Madeira to check the airline's website before travelling to the airport.