Solar Impulse 2, the first attempt at a solar-powered round the world flight, has successfully landed at Muscat International Airport in Oman after completing the first 250-mile (400km) stint of its journey.

The aircraft, which is the only solar airplane capable of flying both day and night, travelled from Abu Dhabi to Oman in a journey lasting 13 hours and two minutes that started this morning at 3.12am GMT, the first part of its five-month journey that will see it cover 22,000 miles (35,000km).

The purpose of the stop-over is to switch the pilots, with Bertrand Piccard taking over from fellow Swiss national Andre Borschberg, ahead of the next leg of the journey, which will head towards India.

The two pilots, who will fly the plane in alternating shifts, will have to contend with some testing conditions aboard the plane as they fly alone for up to five days at a time. They will use yoga and self-hypnosis to keep themselves occupied.

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Conditions in the cockpit might not be wholly enjoyable, though, as the pilots will not only live and sleep there, but their chair also doubles as a toilet.

If the mission is successful, though, the plane will represent a considerable achievement for solar power as the plane uses only solar energy to power its four engines, and not a single drop of conventional fuel will be used as it crosses three continents and spans two oceans.

Solar Impulse 2 departing from Abu Dhabi. Photo / AP
Solar Impulse 2 departing from Abu Dhabi. Photo / AP

They aim to rest a maximum of 20 minutes at a time, taking short catnaps similar to those taken by round-the-world yachtsmen, and will repeat the naps 12 times over a 24-hour period to get six hours of sleep. Goggles worn over the pilot's eyes will flash lights to wake them up.

Neither pilot will be able to stand in the cockpit while flying, but the seat reclines for stretching and its cushion can be removed for access to a toilet.

Armbands placed underneath their suits will buzz if the plane isn't flying level, while an electronic co-pilot keeps the plane steady when they take a short nap. However, the plane is too delicate for auto-pilot, so they must frequently take back control.

The plane does not have a pressurised cockpit so the pilots will be subjected to the changing temperatures outside, which will range from -40 to 40°C (-40 to 104°F). The cockpit also does not have air conditioning or heating, but it is insulated to try and help the pilots maintain a steady temperature.

The pilot's blood oxygen levels will constantly be monitored and sent back to ground control.

The plane will reach an altitude of around 28,000ft (8,500 meters) during the day to catch the sun's rays and at night it will dip to around 5,000ft (1,500 meters) when flying over the ocean.

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'You have to make the cockpit like your own house for a week in the air,' said one of the two pilots, Bertrand Piccard from Switzerland.

The first leg of the trip began at Al Bateen Executive Airport in Abu Dhabi after being delayed from Saturday when strong winds prevented the aircraft from taking off.

The successful launch capped 13 years of research and testing by the two pilots.

From the control centre in Monaco, Crown Prince Albert spoke to Borschberg as he sat in the cockpit waiting for takeoff, wishing him good luck as the event was streamed live online.

From Oman the plane will fly to Ahmedabad and Varanasi in India, Mandalay in Burma, then on to Chongqing and Nanjing in China. It will then take five days and nights to fly to Honolulu in Hawaii, before crossing the US.

That leg will take in Phoenix, Arizona, and JFK airport in New York, followed by a crossing of the Atlantic to either southern Europe or northern Africa.

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The first attempt at a solar-powered round-the-world flight, has successfully landed at Muscat International Airport in Oman after completing the first 400km stint of its journey. Photo / AP
The first attempt at a solar-powered round-the-world flight, has successfully landed at Muscat International Airport in Oman after completing the first 400km stint of its journey. Photo / AP

The final leg will take the craft from either of those locations back to Abu Dhabi, where it will make its final landing. All this will happen without burning a single drop of fuel, and is seen as being a major revolution in solar power technology.

By 2050, it is estimated that solar power could become the world's dominant source of energy, and while Solar Impulse 2 is not particularly bringing any new technologies to the table, it is proving just how far solar power can go.

'It wasn't the people selling candles who invented the lightbulb,' Piccard said previously.

'This project is a human project, it is a human challenge,' said Borschberg, co-founder and chief executive of Solar Impulse, who flew the plane on the first leg.

Borschberg and Piccard will alternate turns at the controls in the cockpit because the plane can hold only one person.

'We want to share our vision of a clean future,' said Piccard, chairman of Solar Impulse.

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'Climate change is a fantastic opportunity to bring in the market new green technologies that save energy, save natural resources of our planet, make profit, create jobs, and sustain growth.'

Piccard comes from a family of adventurer-scientists and was the first person to circumnavigate the globe in a hot air balloon in 1999.

He said his idea of solar-powered flight was ridiculed when it was first proposed, but he said the project proves that you 'can achieve the impossible'.

The plane is powered by more than 17,000 solar cells built into wings that, at 236ft (72 metres) wide, are longer than a jumbo and approaching that of an Airbus A380 superjumbo.

But thanks to a lightweight carbon fibre design, the aircraft only weighs only 2.3 tonnes, about the same as a family 4X4 and less than one percent of the weight of the A380.

It will travel at 30 to 60mph (50 to 100km/h), with the slower speeds at night to prevent the batteries from draining too quickly.

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The Si2 is the successor to Solar Impulse, a smaller craft that notched up a 26-hour flight in 2010, proving its ability to store enough power in the batteries during the day to keep flying at night.

It made its last successful test flight in the United Arab Emirates on 2 March, and mission chiefs reported no problems.

It is scheduled to arrive back in Abu Dhabi in July, flown by Piccard.

The pilots will be linked to a control centre in Monaco where 65 weathermen, air traffic controllers and engineers will be stationed. A team of 65 support staff will travel with the two pilots.

The incredible journey of Solar Impulse 2

To break up flying day and night, Solar Impulse 2 will stop in 12 locations around the world.

After taking off in Abu Dhabi, capital of the United Arab Emirates, it stopped in Muscat in Oman before heading to Ahmedabad and Varanasi in India.

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From there, it will fly to Mandalay, Burma, before making two pit stops in China at Chongqing and Nanjing.

The solar-powered plane will then cross the Pacific Ocean via Hawaii.

A pit-stop in the south west of the US will be chosen depending on weather conditions, before the Solar Impulse 2 stops off at Phoenix and at JFK airport in New York City.

After crossing the Atlantic Ocean, it will make a stop somewhere in southern Europe, before undertaking the final leg of its journey to land back in Abu Dhabi in July.

The 22,000-mile (35,000km) trip will span 25 flight days, spread over five months.

The two pilots, together with a crew of 80 technicians, engineers and a communications team, were in Abu Dhabi for a fortnight before take off this morning conducting safety tests, test flights, and training.

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During stopovers, people will be able to visit the airplane and Google Hangouts will be hosted.

- Daily Mail