A solar plane attempting to fly around the world without a drop of fuel made an unscheduled stop Monday night in Nagoya, Japan, because of bad weather over the western Pacific Ocean.
Swiss pilot André Borschberg took off from Nanjing, China, on Sunday on what was to be the longest leg of the journey, a six-day, 8,175-kilometer (5,079-mile) flight to Hawaii.
Instead, the Solar Impulse 2 landed in Nagoya in central Japan after flying a total of 44 hours and 10 minutes.
.@andreborschberg flew #Si2 during 44 hours and 10 minutes, from Nanjing to Nagoya! http://t.co/teTGlH1vfY pic.twitter.com/iuNZs8qBod— SOLAR IMPULSE (@solarimpulse) June 1, 2015
BREAKING NEWS: Weather window toward Hawaii has deteriorated. We decided to make an intermediate landing in Nagoya! pic.twitter.com/crziXXRX10— SOLAR IMPULSE (@solarimpulse) June 1, 2015
The Solar Impulse 2 team cited a cold front that was draped from northeast to southwest between Japan and Hawaii as the reason for the unscheduled landing, saying on Twitter that it constituted a "wall" blocking the flight. The plane requires ample sunshine to charge its batteries in order to continue flying at night, and the cloudiness associated with the cold front would interfere with this, presenting a potential danger to the already risky mission.
Japanese Transport Ministry and Nagoya airport officials confirmed that they are making arrangements for an unanticipated landing at Nagoya Airport.
Elke Neumann, a spokeswoman for the Solar Impulse project, said from Nanjing that the team first noticed the inclement weather pattern about 36 hours ago.
"We thought we might go through it," she said. "But between Japan and Hawaii there's no place to stop."
The safety of the pilot and the plane are a priority, and they will likely wait a few days in Japan until the weather changes, she said. The plane landed after scheduled flights at the airport ended around 10 p.m.
Solar Impulse 2 needs room to land, so it generally avoids times when commercial flights are operating, Neuman said. The plane also usually lands at night, because the winds tend to be lower. It needs wind to be no more than 10 knots, she said.
Landing in Nagoya japan was not planned but there must be a good reason why our path has brought us here today pic.twitter.com/7Tu8YA67pf— André Borschberg (@andreborschberg) June 1, 2015
"We are a little bit sad, because everything's functioning perfectly: The batteries are charging, there's enough sun, the pilot is in good health, he's in good condition — it's all working well," Neumann said.
The journey started in March in Abu Dhabi, and the plane has stopped in Oman, India, Myanmar and China. The flight from Nanjing to Hawaii is the seventh of 12 flights and the riskiest.
Andrew Freedman contributed reporting.