Airline passengers are facing massive disruption across the UK after an ash cloud from a volcanic eruption in Iceland grounded planes.
The Air Traffic Control Service (Nats) said no flights would be allowed in or out of UK airspace from midday to 1800BST amid fears of engine damage.
All flights at Heathrow, Stansted and Gatwick will be suspended from midday and in Scotland all airports are shut.
Passengers were also affected in Norway, Sweden, Finland and Denmark.
The UK restrictions, in accordance with international civil aviation policy, were imposed after the Met Office warned ash could clog engines.
Passengers were advised to contact their carriers prior to travel.
Experts have warned that the tiny particles of rock, glass and sand contained in the ash cloud would be sufficient to jam aircraft engines.
Thousands of passengers have faced severe travel disruption
Aberdeen, Edinburgh and Glasgow airports were shut as Nats said it was restricting flights "in accordance with international civil aviation policy".
One passenger at Glasgow told the BBC: "I'm meant to be going to Lanzarote. We've travelled from Oban, leaving at 3am. Now we've decided we might as well just go home and do a bit of gardening."
The ash cloud disrupted all flights to and from Manchester with a similar picture at Newcastle airport and Liverpool's John Lennon airport.
Flights were affected at London's Gatwick, Heathrow and City airports, and British Airways said it had cancelled all domestic flights for the whole of Thursday.
The company said it would refund its passengers or offer the option of rebooking.
A Royal Air Force Sea King helicopter was forced to fly a critically ill patient from Scotland to London following the cancellations.
She was flow from HMS Gannet at Prestwick to Regent's Park, then on to University College Hospital.
http://news.bbc.co.uk/1/hi/uk/8621407.stm
