Thousands flying out of the UK today face flight cancellations as the ash continues to drift from a volcanic eruption in Iceland. All major operators flying in and out of Scotland cancelled flights on Tuesday morning.
Flights in northern England have also been grounded. KLM and Eastern Airways announced that flights from Newcastle and Durham Tees Valley airports would remain grounded this morning.
Philip Hammond, the UK transport secretary, said the decision not to fly had been made by airlines themselves.
Air travellers across Britain are advised to check with their airlines before travelling.
Eurocontrol, the European air safety organisation, said low density ash cloud was expected to be in place over Heathrow by 1pm, but it was unclear whether this would be serious enough to affect scheduled flights.
British Airways announced it had cancelled all flights from Heathrow to Scotland until 2pm at the earliest, as have easyJet, Flybe and Loganair.
Ryanair has cancelled all flights to and from Edinburgh, Aberdeen and Glasgow Prestwick.
The disruption came just over a year after the eruption of the Eyjafyoll volcano forced the closure of British airspace.
Barack Obama cut short a visit to Ireland to fly to England on Monday night, rather than waiting until Tuesday morning as originally scheduled, due to fears over the ash cloud.
According to the CAA, all British aircraft can fly in medium density ash, but Met Office charts show that the levels are higher than this below 35,000 feet, meaning planes could have to navigate routes around the plume.
Ryanair has objected to advice from the Irish Aviation Authority (IAA) not to operate flights to and from Scotland.
In a statement on its website, the airline said: “Ryanair strongly object to this decision and believe that there is no basis for these flight cancellations and will be meeting with the IAA on Tuesday morning to have this restriction on Ryanair flights removed as a matter of urgency.
“Ryanair believe that there is no safety risk to aircraft on fights operating to and from Scotland and together with other airlines will be complaining to the Transport Minister and regulatory authorities about these latest and unnecessary cancellations.”