THE giant plume of volcanic ash that forced the unprecedented closure of British airports and is affecting large swathes of northern Europe may persist for another five days, stranding hundreds of thousands of passengers worldwide.
As the Eyjafjallajokull volcano continued its show of lava, fire and cascades of melting ice the size of houses, airlines warned passengers the flight bans may not be lifted in the short term.
Australians booked on British Airways to London over the weekend have already had their flights cancelled and have been told to await new instructions.
The volcano, which is on the southern tip of Iceland, last stirred in 1821 and records show its eruptions continued intermittently for two years.
This is the first time in aviation history that Britain has closed its airspace completely - a decision not even taken in the aftermath of the terrorist attacks on September 11, 2001. Analysts have estimated that the closure could cost airlines more than £100 million ($165 million) if the disruption stretches into the weekend and the wider economy will suffer as tourism and movement of goods, including food, from Europe is halted.
Sharemarkets responded to the chaos and millions was wiped off the value of British airlines, including Ryanair, which grounded its British and Irish flights and lost £70 million from its market value. BA fell £4.5 million and easyJet dropped £5.6 million.
A prevailing north-westerly wind is to blame for the carriage of fine ash from Iceland, creating a sulphurous smell in some parts of Scotland, a coating of fine dust in other places and spectacular purple sunsets in many parts of northern Europe.
Air traffic authorities in Britain have defended their decision to call for a shutdown, arguing safety is paramount. ''Volcanic ash is a serious threat to aircraft,'' a spokesman for the National Air Traffic Service said.
Gaille Mackinnon, an Australian forensic anthropologist based in Britain, is stranded in southern Spain and was one of the first travellers to receive news that the plume had closed flights.
She received a text message on Thursday warning of her flight's cancellation. ''I'm lucky because I am staying with friends and do not have the hassle of finding a hotel,'' she said. She is due to fly on to Australia for her parents' 50th wedding anniversary.
''I'm now on another at 11pm on Saturday … Nobody knows if we will be travelling by then.''
As the disruption looked set to continue, many travellers prepared for another uncomfortable night in airports across Europe.
"I've been here since 9am yesterday, it looks like we're going to spend another night here," Tolga Aydin, a young Canadian trying to get to Toronto, said from his makeshift bed on a bench at London's Gatwick airport.
In the past 20 years, there have been 80 recorded encounters between aircraft and volcanic clouds, causing the near-loss of two Boeing 747s with almost 500 people on board and damage to 20 other planes, experts said.
Finnish fighter jets that flew through the volcanic dust on training flights on Thursday suffered damaged engines, the air force said.
US air carriers also grounded flights to Europe for a second day on Friday.
The current eruption is small fry compared to the eruption of Iceland's Laki volcano in 1783, which some experts consider to be the most devastating in history.
The eruption of the Laki, in the same southern part of the nordic island where this week's eruption took place, was much more devastating, killing almost a quarter of the population and tens of thousands of people across Europe.
On June 8, 1783 the volcano was ripped open with such force that a huge fissure produced about 130 boiling craters. The eruption threw tonnes of fluoride-bearing ashes into the sky.
The local population died not from the eruption itself but due to inhaling the poisonous gases, and after famine as the fall-out decimated livestock -- killing more than half of sheep and cattle.
The eruption continued until February 7, 1784. An estimated 122 tonnes of acid were projected into the atmosphere. The poison cloud headed for Norway than descended towards Germany, France and Britain.
As it made its course through Europe, it became known as the Laki fog. In Britain the summer of 1783 became known as the summer of sand because of the raining ash.
According to researchers at Britain's Cambridge University, more than 20,000 Britons died after inhaling the gas.
The meteorological effect of the eruption was felt for several years, with the winter which followed the eruption being particularly harsh and mortality rates peaking.
The effects were also felt in France, which saw periods of drought and extreme summers and winters and hail storms which destroyed the harvests.