All but a few flights in and out of the UK will remain grounded until 1am tomorrow, it was announced today.
Making the latest no-fly decision, British air traffic control company Nats said the cloud of volcanic ash from the Iceland eruption continued to cover much of the UK.
But Nats did say some flights in Northern Ireland and the Western Isles of Scotland to and from Glasgow and Prestwick would continue to be allowed until 7pm today and that some transatlantic flights to and from Glasgow, Prestwick and Belfast could be permitted as well.
Nats said that from 7pm today forecasts indicated Scottish airspace may be able to accept domestic flights within Scotland and Northern Ireland and the Republic of Ireland, and North Atlantic flights to and from airports in Scotland and Northern Ireland.
Describing the situation as "dynamic and subject to change", Nats said it would be reviewing the latest weather information at around 1pm today and making a further announcement about flights at about 2.30pm.
Nats added: "We continue to work closely with airports, airlines and the rest of Europe to understand and mitigate the implications of the volcanic eruption."
While airports in England will remain flightless and deserted until tomorrow, there was some activity in Scotland today.
An Air Transat flight from Glasgow to Toronto left at 8am and three transatlantic Thomson Airways' flights were due to land at Glasgow.
At Glasgow, Jean and Michael McLoughlin said their daughter had left on the Air Transat flight.
The retired pair drove through the night from their home in Durham when they heard the flight may go ahead.
It was their second trip in two days. The family returned to Durham yesterday when they got to Glasgow to find the Canada flight cancelled.
Mrs McLoughlin said: "She works in Toronto and needs to get back."
She said her daughter had made a surprise visit to Durham for her father's retirement party.
Flight restrictions over the UK have been in place since noon on Thursday as aviation authorities take no chances of aircraft being caught up in the ash cloud emanating from the Icelandic mountain Eyjaffjallajokull.
Similar flight restrictions have been put in place over much of northern Europe in the biggest disruption to world aviation since the 9/11 terrorist attacks in the US.
The airport shutdown comes at a time when airlines are struggling to recover from the worst effects of the recession.
For British Airways, which had to cope with seven days of strikes by cabin crew last month, the latest disruption is particularly cruel.
Heathrow airport, BA's main base, would normally have handled around 1,300 flights today. Gatwick would have handled 730 flights and around 90,000 passengers.
Airspace restrictions affecting Manchester airport began at 7am on Thursday. Between then and 1am tomorrow, the airport would normally have handled 385 arriving flights, 562 departing flights and 142,000 passengers.
Nats has defended its shutdown decision, saying safety is paramount - a sentiment echoed by Prime Minister Gordon Brown.
But independent aviation marketing intelligence company the Centre for Asia Pacific Aviation (Capa) today questioned whether the restrictions were really necessary.
Capa said: "Much of European airspace is closed for today at least. Within Europe the scene is casual chaos. Not only are travellers and flights grounded in several major European cities, but it will take days to restore schedules, even if the scare is called off today.
"And in points as far away as Australia and Argentina, aircraft bound for Europe have been grounded too. Is this a massive over-reaction of super-cautious politicians and bureaucrats who are far more concerned about their own liability - while suffering none of the financial carnage that this will cause the airlines and their feeding chain? Or is it a genuinely serious event that justified shutting down most of Europe's airspace?"
Capa went on "The question is, what happens if Iceland's Eyjafjallajokull glacier volcano keeps on erupting - for days, or weeks?
The Vatnajokull eruption in Iceland in the 1990s (a similar event under a much bigger glacier) led to minimal disruption, apart from a short period when the eruptions began, with aircraft routed around the area. It certainly did not lead to region-wide closures of air space. Such has the paranoia around safety and security grown since 9/11.
"Recovery in the key transatlantic business market (the lifeblood for many European and US long-haul airlines) is still elusive, while short-haul premium (business and first-class) demand within Europe continues to contract. Airlines' finances, particularly in Europe, remain fragile, and airline managements will be hoping the ash - and the attendant paranoia - settles quickly."
For a second day running air passengers scrambled to take up other travelling options.
Channel Tunnel high-speed train company Eurostar reported a sell-out of its 48 London St Pancras to and from Paris and Brussels services.
A spokeswoman for the company said: "We are carrying more than 38,000 people today and all our trains are full.
"We are telling potential customers without bookings not to come to St Pancras because they will not be able to travel."
She went on: "We expect to be very busy over the weekend as well. This is a popular time anyway, with people wanting to get away on spring breaks."