By RAY MASSEY

Last updated at 00:59 07 August 2007

With triple-decker bunk-beds stacked from floor to ceiling, it looks a cross between a school dormitory and the sleeping quarters on a troop ship.

But thrifty fliers take note. German airline Lufthansa is considering introducing just such an economy sleeper cabin on its long-haul flights.

It would, for the first time, offer economy-class passengers a bed rather than a seat for a more comfortable ride.

The triple decker bunks are set out in the herring-bone pattern of a kipper - designed to give the maximum number of passengers the chance of a kip.

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The fly-and-lie "kipper class" service is likely to take place first on the giant Airbus A380, giving budget fliers the chance of a horizontal snooze that, until now, is the preserve of business and First class fliers.

But it could be adapted to most long-haul aircraft.

Details of the idea - which would radically alter intercontinental travel - emerged yesterday as the airline hailed encouraging feedback from customers quizzed in an online poll.

Lufthansa spokeswoman Amelie Lorenz said: "We are going to analyse the results of the survey and then we will decide whether to proceed or not. But the first results have been very positive."

Most airlines already provide flat bed seats on their long-range routes, but only for first- and business-class customers.

Economy-class passengers have had to settle for being packed into tightly regimented reclining seats for extended periods of travel, which have been blamed for causing potentially fatal blood clots known as deep-vein thrombosis, or DVT, in susceptible individuals.

Until now, airlines have been reluctant to introduce fully reclining seats in economy class because they require more space.

This reduces the number of passengers and decreases profit for the carriers.

But by stacking beds one on top of another, the airline can make use of the normally unused space in the cabin above fliers.

Lufthansa revealed computer-generated pictures of its triple-decker bunk beds as part of a customer survey it conducted among selected customers to see if the idea had wings.

The official picture, which the airline was nevertheless reluctant to release, features a layout of berths stacked three-high in diagonal rows - herringbone-style - along the sides of the plane. There are two additional rows bunked berths at the centre of a wide central aisle.

The high-density bunk-beds would allow the airline to accommodate enough passengers, while still providing them with the luxury of a good night's sleep on an overnight flight, without having to charge them a £3,000 price tag.

Miss Lorenz noted that the proposed layout - which appeared to represent the lower deck of the twin-level Airbus A380 - was just one of those under consideration.

If the airline decides to go ahead with the proposed sleeper cabin, the best option will be selected, she said.

The A380 - the world's largest airliner - will fly on Lufthansa's ultra-long haul flights, including those from Germany to North America, South Africa, the Far East and Australia. It has already flown long-haul, staffed with a full Lufthansa crew and VIP passengers, to Hong Kong and the United States.

If the new "kipper class" idea is adopted, the airline would have to fine-tune how the beds would be adjusted to enable passengers to eat meals - and how the cabin would be configured for take off and landing.

But Lufthansa suggested it was ready for the challenge.

The bunk beds would be transformed from seats after take off and would cost around £120 more than a flexible economy fare.

They would be linked to the flight entertainment system but would be unlikely to include a meal service, other than a light snack and bottled water from the buffet, because passengers booking them would be anxious to get their heads down to sleep as quickly as possible.

The bunk beds would have to be approved by the international safety authorities, who would consider ease of evacuation in an emergency.

Business travellers on passenger websites have broadly welcomed Lufthansa's bunk bed idea.

One passenger noted: "The prospect of being able to get a decent night's sleep on a flight without having to fork out a four figure sum would be a monumental step forward for air travel."

Another said: "I think that it could prove very popular with business travellers whose companies are too stingy to let them fly business class. Even with the £120 surcharge, this should still be within the range of all but the most draconian corporate travel policies."

Miss Lorenz said: "This is part of an innovation process within our airline. It is part of our normal product development."

Sir Richard Branson's Virgin Atlantic will be the first UK airline to take delivery of the A380 superjumbo and has already expressed an interest in putting beds into its planes.

Sir Richard even went as far as suggesting it could have private cabins costing from £2,000 which he dubbed "the Mile High Club."

Three years ago he said: "It has been one of my long held ambitions to have double beds onboard our aircraft and now, once again, we are leading the way in product innovation onboard our aircraft."

British Airways has yet to commit to buying any A380s.

More than a decade ago some aircraft engineers came up with the idea of sleeping capsules on planes, similar to the capsule hotels in Japan.