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Solar Impulse 2, a solar-powered airplane attempting an around-the-world flight, departs Nagoya Airfield in central Japan on its way to Hawaii in this photograph taken by Kyodo News June 29, 2015. Reuters

The Solar Impulse 2 is about to complete the most dangerous leg of its record-breaking flight Friday, landing at Hawaii's Kalaeloa Airport sometime around 12 p.m. EDT, according to USA Today. The eco-friendly, solar-powered plane has spent more than 110 hours in the air, setting the record for the longest solo endurance flight.

The stretch from Japan to Hawaii is reportedly the most difficult portion of the flight, because the plane was flying over the vast Pacific Ocean, with very few options in case of an emergency landing. The 4,000-mile trip, already five days long, shot past the previous solo record held by American entrepreneur Steve Fossett, who flew for 76 hours 45 minutes in 2006. The flight also broke the record for longest solar-powered flight by time and by distance, USA Today reported.

The plane -- and mission -- are the brainchildren of the Swiss businessman Andre Borschberg and psychiatrist Bertrand Piccard. Resting only with 20-minute naps, pilot Andre Borschberg tweeted early Friday:

They have already completed a number of the legs of the flight that is attempting to circumnavigate the globe. The trip into Hawaii had been delayed by bad weather for weeks. The undertaking began March 9 in Abu Dhabi, the capital of the United Arab Emirates where it is planned to eventually end. The Solar Impulse 2 will make stops in Phoenix, somewhere in the Midwest and in New York during its American run before setting off to cross the Atlantic Ocean, according to USA Today.

The plane is made of carbon fiber and has a 236-foot wingspan, which is longer than that of a Boeing 747. It is powered only by 17,000 solar cells, and it flies at a speed just above 43 mph.

The Solar Impulse 2 team is running a live stream, featuring commentary and interviews with those involved in the project. It also shows the plane in the air and allows viewers to hear radio contact between pilot Borschberg and those at mission control.

Check out the live stream below:

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