By Finlo Rohrer and Rajini Vaidyanathan
BBC News Magazine
For days no planes have taken off or landed across the UK because of the Icelandic volcano. This has inconvenienced holidaymakers, businesses and schools. How would we cope if the ban went on and on?
At the moment air travel is virtually all by engines powered by kerosene. One day kerosene - like every other fossil fuel - will run out.
So does the effect of the ash cloud hanging over northern Europe give us a valuable insight into what the world would be like with dramatically reduced or non-existent aviation?
How would the UK cope?
We have come to base our holidays around air travel
"I think you'd be talking about going to a situation like the 1950s, when planes were very much the preserve of the upper classes because it was extremely expensive to fly," says a spokesman for the Association of British Travel Agents, Abta.
The main impact would be on long-haul travel. But this would be partly offset by short-haul breaks, to mainland Europe, thanks to improved high-speed train links or ferries. Then again, many of us might just stay at home more.
Figures show that the lion's share of tourism revenue in the UK actually comes from domestic holidaymakers, compared with inbound visitors.
Some categories of tourism would be squashed by the demise of the plane. The foreign weekend break to anywhere other than a small segment of north-western Europe would no longer be viable.
But to the environmentally-minded that might not be a bad thing.
In 2009, 30 million people visited the UK from overseas, and three-quarters of them travelled by plane.
Strip away air travel, and it would inevitably change the shape of the tourism industry, but not all for the worse, says a spokesman for Visit Britain, the organisation responsible for promoting tourism here.
"Although fewer people would be coming in, we'd hope that people would take the opportunity to visit the whole of Britain in a way they wouldn't consider doing normally," says the spokesman.
One of the biggest concerns might be a potential loss in revenue generated by foreign tourists.
While visitors to the UK from other countries outnumber Americans, those from the US spend the most - £2.2bn a year. Take away air travel and that revenue seam would vastly diminish.
Exotic fruit and fresh chillies often come by air
The good news in a flight-less world is that Britain would still get enough to eat. Moreover, it would still get its share of tropical fruit and vegetables.
"The impact is not massive. We only import 1.5% of all our fruit and veg by air," says Michael Barker, fresh foods editor at the Grocer magazine.
Tesco goes along with this picture, saying less than 1% of all its stock comes by air. At the higher end of the market, Waitrose also says the proportion is tiny.
Specific examples might include fresh mangoes from Ghana, asparagus from Peru and papayas. They are not exactly staples of the British diet.
Much of the food that comes from abroad, comes on "reefers", special refrigerated ships, or in refrigerated containers on ordinary ships. If you need an out-of-season apple from New Zealand, it comes on a ship. Within Europe, much of the distance from field to plate will be covered by road and rail.
And of course, there has been continuous pressure in the past few years from environmentalists to eat more local and seasonal food.
But one thing we really do need planes for is the UK's floral industry. Many of our flowers come from Africa, particularly Kenya, and they are much more perishable than most other produce.
The industry would have to be radically reshaped to cope with the loss of aviation, says Jason Rodgers, retail director of the British Florist Association. More than 80% of the flowers sold by florists in the UK come through the Netherlands, which is an international nexus for auctions.
They come to the UK often by road or rail, but they will often have got to the Netherlands by air from Kenya, Zimbabwe, Ethiopia, Colombia and other supplier nations.
Brushing up on his semaphore - ferry passenger Dizzee Rascal
Even if there were no planes, the show would go on. It just might look and sound a bit different.
"No air travel doesn't necessarily mean no entertainment, but it could affect the kind of artists who would come and tour here", says Matt Wooliscroft, a concert promoter for SJM concerts.
For Mr Wooliscroft, this week has shed a light on how tricky arranging tours can be without the benefits of aviation. The Icelandic volcano has meant one of his bands, the Australian group Powderfinger, have had to reschedule their tour dates. Some members of another act he works with, Alphabeat, are stuck in Norway, and are trying to see if there are ways they can travel overland to fulfil their UK tour commitments.
Looking at a hypothetical scenario with no planes, the Australian and US music acts would be hit the hardest, says Mr Wooliscroft. When it comes to European artists it might not make such a dent, he explains, because most bands travel across the continent on their trusted tour buses anyway.
"For the smaller American bands, it'd be less cost effective to tour. For the bigger bands, if it took them a week or two to get here by boat they may not be able to afford the time to do that."
This week has seen some celebrity spottings on ferries however, with both Whitney Houston and Dizzee Rascal making the trip to Dublin on the ferry to honour concert commitments.
Issues with air travel have played havoc with the lives of sports people
In a plane-free world, the nature of travelling by sea could fundamentally alter in terms of cost and speed, says Mr Wooliscroft, so the journey across the pond to play a gig, might not be as painful as one might imagine.
Sport needs aeroplanes. If you take football as your example, the number of games played every season is sustained by the availability of air travel. This week Liverpool will have played a Premiership match against West Ham on Monday, immediately started a 1,300 mile overland journey to Madrid to play a Europa League semi-final against Atletico Madrid before getting straight back on the road to get to Burnley for another Premiership match on Sunday.
It can be allowed as an exhausting one-off now, but a prolonged absence of plane travel would mean massive changes to the structure of sport.
Once upon a time cricketers spent weeks sailing to play in the Ashes in Australia, but now the game sees international cricketers fly to play 20/20 in India before hopping back to the UK for county cricket or off somewhere else for a test.
The effect on British business would not just be in terms of tourist disruption or impossible air freight.
"We are an island nation and without that ease of use and connectivity we would be cut off," says Gareth Elliott, senior policy adviser at the British Chambers of Commerce.
The increasingly globalised world we live in has been made possible by - among other things - the rise of air travel. Video conferencing has made it possible to hold meetings without leaving the comfort of your office, but for many critical deals and projects, a face-to-face meeting is necessary.
"People want to meet each other," says Mr Elliott. "They want to be able to greet and shake hands."
"Sometimes it is as simple as seeing goods you are buying or selling. You need to speak to the people who are doing it, gain their trust."
There are circumstances where nothing else will do. No matter how convincing the balance sheets, how regular the video conferences and how trusted the middle men, a Far East business person is not going to buy a business in the UK without coming here first to check it out. A big deal may require a series of visits by different people.
Having to go by ship or not at all would impede that process.
And the change in the nature of industry in the UK makes air travel more important than ever before.
"As we have moved up the value chain, consultancy has grown significantly in terms of the share of exporting our skills to other countries. This is a high value knowledge economy where you need to move these people."
Location, location... in this case, down the road from Heathrow
He gives the example of ARM Holdings, which designs processor chips.
"They need to move people rather than goods. Aviation is vital. If you look at some of the UK's biggest businesses they are always located within easy reach of an airport."
Pharmaceutical and consumer goods giant GlaxoSmithkline is a case in point - siting itself next to the motorway that leads to Heathrow airport, he says. It is where it is to be near Heathrow, and so connected with the world.
But for Prof Helen Walker, an expert in sustainable supply chains and corporate social responsibility at Warwick Business School, the insight we are currently having into a Britain without flight is a useful exercise.
"We have in the last 10, 20, 30 years been moving increasingly towards off-shoring our manufacturing to drive down costs. We have got increasingly complex global supply chains.
"If we are reliant on suppliers in other countries, it is necessary to have multiple sourcing strategies."
She concurs with the analysis of the UK's changing economic base.
"Britain as a nation has become more a service sector nation. That makes us vulnerable."
THE GOOD SIDE
Many residents are sick of the sight and sound of these
It's important not just to think about what we would lose if air travel was to come to an end.
There are those who would welcome just such a scenario.
"Of course a complete halt in air transport would be dramatic, but transport by water and land would re-emerge and essentially suffice," says John Stewart, chairman of HACAN Clearskies, which campaigns to mitigate the impact of aircraft in London and the South East.
"We would lead more localised lives - communities have become dispersed with the invention of the motor car and even more so now that we use aeroplanes."
The group is not campaigning for an end to planes, but their enforced absence has been a bonus in the last few days for many residents near to airports, he says.
"For the first time in years they have had a sequence of five or six good nights' sleep, and they feel calmer for it."
A lady of 60 e-mailed him, saying: "For the first time in decades [I'm] able to sit out in the garden for more than 20 minutes at a time and linger over the sound of the birds
and there isn't the feeling that they will start again soon, fearing a plane is going to come and take it all away."
Additional reporting by Ian Haigh
Below is a selection of your comments
While the points raised in this article are very important, I feel you have left out one major area: war. The modern military machine of the western world completely relies on air superiority, and the ability to be able to move by air.
Cullum Welch, Milton Keynes
I was born, raised and still live under the flight path into Manchester Airport. For 53 years the noise of aircraft has blighted my life. I'd wager that everyone who lives in Stockport in the east or Mobberley and Knutsford in the west has enjoyed the most peaceful week of their lives. We haven't missed the planes one iota. Long and hard may Iceland's volcanoes erupt.
Paul Reid, Stockport, Cheshire
A slightly flawed argument, as the proposition was that kerosene would run out: If that was the case, then the shipping would be stopped as they ran out of diesel and kerosene too.
Ben, Coventry, UK
Please, please, please. Not ALL flights in the UK have been banned. Sport aviation, such as the microlighting run by my flying school, is operating normally - except that customers think it isn't because all they hear about is that "all UK airspace is closed".
Colin MacKinnon, Strathaven, South Lanarkshire
Perhaps vacuum transport will now become economic. It is the large-scale equivalent of the tubes used in large stores to send capsules of money etc. to the accounts departments. In theory, the journey from the UK to New York would take less than 30 minutes in a large diameter plastic pipe suspended from floats on the surface of the Atlantic. Passengers would be accommodated in a capsule within the tube being propelled into the vacuum by atmospheric pressure behind it. Not a new idea but one that should be investigated again.
Organ transplantation would certainly take a hit. Human tissue is only viable for a short period of time after being removed from a body, and with no air transit, the people in the greatest need may not be able to get organs from the other side of the country.
Julia Kite, London, UK
Surely, if this situation did look likely to continue indefinitely, then at last people would see sense about bringing back airships. Modern, high-speed airships - safer, cheaper, greener and cleaner than planes, maybe a bit slower, but far better for the world in the long run.
W Wilcox, London UK