Air passengers fear for the worst after the Grimsvötn volcano erupted over the weekend and sent a plume of ash 12 miles into the Icelandic air. With the memories of last year’s chaos still fresh in their minds, thousands of passengers are facing delays and cancellations.

Some flights to and from Scotland have been halted due to safety concerns as the cloud drifts south towards Edinburgh and Glasgow. Although airports remained open, airlines including British Airways, easyJet, Ryanair and KLM decided to err on the side of caution and keep their flights grounded. BMI was one of the airlines that continued to run out of Edinburgh and Glasgow, saying that by their judgement, the cloud was still further north than expected.

Meteorologists have warned that the cloud could spread slowly south, which would affect flights to Northern Ireland and the north of England. The worst-case scenario forecasts show that high-density ash could affect southern England by Friday.

Philip Hammond, the transport secretary, said that the British public has to “learn to live” with disruption after the travel chaos caused by the ash cloud last year and the heavy snowfall over the last two winters. Although he insisted that they had the systems in place to minimise disruption, he stressed, "what we can't promise is that there won't be disruption when there is a major natural event like this."

The factors determining the extent of disruption are the amount of ash the volcano produces, and the wind speed and direction. Mr Hammond said the latter was particularly difficult to judge at present, “the weather patterns are very volatile which is what is making it quite difficult to predict where the ash will go."

Since last year, UK policy has changed to now allow airlines to request permission to fly through ash clouds. To be granted permission to fly they must make a sufficient safety case, which must demonstrate that their carriers can cope with medium or high-level densities of ash.