President Obama who is currently in Ireland was forced to shorten his visit and fled to London for a state visit.
Andrew Haines, chief executive of the Civial Aviation Authority, said he hoped to avoid the repeat of 2010 travel chaos and said: , "We know so much more about the volcanoes. We have an improved model."
"We have better measuring equipment and we have better relationships with airlines so it should be much better but we're still at the hands of both the weather and the volcano; those are the two uncertainties."