Solar-powered plane ‘past point of no return’

As the sun rises yesterday, the Solar Impulse continues its Pacific journey. Picture: AFP/Getty

Solar Impulse took off from Japan’s Nagoya airfield at 6:03pm GMT on Sunday and the journey to Hawaii is expected to take approximately 120 hours.

The team spent nearly two months waiting for clear weather, and a developing cold front forced the plane to make an unscheduled landing in Japan earlier this month.

“[Pilot] Andre Borschberg has passed the point of no return and must now see this 5 days 5 nights flight through to the end,” the Solar Impulse website reported.

Pilot Andre Borschberg does his preflight checks. Picture: Getty

He no longer has the option to turn around and return to Japan, if the weather forecast changes.

The first attempt to fly over the Pacific was cut short after a change in the forecast forced an unscheduled landing.

Another attempt to take off last Tuesday was cancelled at the last moment because of concerns about the conditions.

If the pilot succeeds, it will be the longest-duration solo flight in aviation history, as well as the furthest distance flown by a craft that is powered only by the Sun.

The Pacific crossing is the eighth leg of Solar Impulse’s journey around the world.

But this stage has proven to be the most difficult, and has been hit by weeks of delays.

Solar Impulse co-founder Mr Borschberg, who is flying the experimental single-seater craft, was initially supposed to begin his journey to Hawaii from Nanjing in China.

But he spent weeks there, with his ground-support team, waiting for the right flying conditions to present themselves.

He finally took off on 31 May, but a deterioration in the forecast a few hours into the mission meant he had to divert to Japan. The rainy season in Nagoya has meant another long wait there – but after the false start last week, meteorologists are confident they have found a weather window to make the five-day, five-night crossing to Hawaii.

The plane is heading straight out across the Pacific. “We really are in the moment of truth now,” Conor Lennon, a member of the Solar Impulse team said from the project’s headquarters. “It’s the moment of truth technically and in human terms as well. Can the plane manage it?”

Bertrand Piccard, the Solar Impulse co-founder and occasional co-pilot, said: “There’s a lot of uncertainty at the end – we cannot know everything. Today we accepted the decision to go, we accepted that risk … we believe the window is good.”

The experimental craft – which has 17,000 solar cells – is powered only by the Sun.

Once over the ocean, if it fails to soak up enough rays to fully charge its batteries and make it through the night, the pilot could be forced to bail out. Mr Borschberg has been trained for that eventuality. He has a dinghy and enough supplies for several days while he waits for the team to pick him up.

But, of course, the team is hoping that none of this will be necessary.

Mr Borschberg will spend the duration of the flight strapped into his seat in a cockpit about the same size as a phone booth. He will be have only 20-minute cat-naps but says he will use yoga and meditation to make his journey more comfortable.

If this flight succeeds, the plane will continue its journey around the world, with Mr Piccard taking the controls for the next Pacific crossing from Hawaii to the US mainland.

The plane will then continue across North America, before attempting to fly over the Atlantic.

However, the build-up of delays could impact on the later stages. Ideally, the plane needs to cross the Atlantic before August, when the hurricane season reaches its peak.