Transport secretary Philip Hammond has said there will be "no crude nationwide ban" on flights, even if ash from Iceland's latest volcanic spreads across the UK.
Fall-out from the Grimsvotn volcano has forced airlnes to cancel flights to and from Scotland this morning, but Hammond said this would not lead to a blanket ban on flying.
Lessons have been learned from the volcanic eruption in April last year, which led to more than 63,000 flights being grounded when northern European airspace was shut down for six days.
In particular, airlines know more now about what levels of ash pose a safety risk to flights. Hammond said the current situation was being closely monitored and he said that if ash was detected over the UK, individual airlines would have to present evidence to the Civil Aviation Authority that they could continue to fly safely.
Dr Dave McGarvie of the Open University said that although the Grimsvotn eruption is at least 10 times more powerful than the eruption last year of the Eyjafjallajokull volcano, it does not pose as big a threat to flights.
This is because the ash is not as fine, it is falling back to earth quicker and the winds are carrying the ash northwards rather than blowing it over the UK, as happened last year.
However, he said airlines would have to take into account a "small additional risk".
Rules about flying have changed since Eyjafjallajokull, he said, which mean that airlines can now fly when ash is present but within very safe limits. "The net effect will be considerably less disruption," he added.
