Plumes of volcanic ash from an erupting volcano in Iceland will bring air traffic to a standstill in the UK at midday today and will also disrupt flights in other parts of Europe.
Only a small number of flights have been allowed to enter UK airspace this morning, with British Airways and Ryanair suspending all domestic flights, and a number of airports, including all of those in Scotland, closing for the day.
Heathrow and Stansted airports were still allowing airlines to operate this morning but said flights will be grounded as of midday. Manchester and Newcastle airports have been closed since early this morning.
Ash from the volcano is expected to enter UK airspace at 1pm today (GMT). The UK is expected to suffer most from the plume, although other airports in Europe, including Oslo's Gardamon in Norway and Amsterdam's Schiphol, have also had to cancel flights.
Northern Sweden, Copenhagen and Finish airports have also been affected and experts say the ash may take two days to dissipate.
It is expected the wind will eventually move the ash south towards the Netherlands and Belgium, but aviation authorities said they will still be cautious following the 1982 British Airways incident when a jumbo lost power in all four engines after flying through a plume of volcanic ash.
A similar incident occurred in 1989 when a KLM flight flying out of Amsterdam hit ash from the erupting Mount Redoubt, which also brought its engines down.
The engines restarted once it had exited the plume but the aircraft was left with a lot of damage.
Aircraft are most at risk from the small particles of glass, sand and rock that volcano ash contains. This can not only create problems for aircraft engines but can hinder the quality of cabin air.