The plane attempting to fly around the world powered only by solar energy is expected to land in Honolulu Friday “around 6 a.m.,” organizers said Thursday morning.

The Solar Impulse 2 took off from Nagoya, Japan, on Sunday for the longest and most dangerous leg of its round-the-world journey. The pilot plans to land at Kalaeloa Airport.

“Due to the nature of this project, these times are subject to change,” said Kathryn Parrish, spokeswoman for Solar Impulse 2 sponsor ABB Ltd.

On Wednesday organizers were predicting the plane could land at anytime between 11 p.m. Thursday and 7 a.m. Friday.

The state Department of Transportation said the public will be able to watch the plane’s arrival from outside the airport.

The spectators can see the runway from the parking area in front of the perimeter fencing on Midway Road between Enterprise Avenue and Lexington Street.

As of 11:45 a.m. Hawaii time Thursday, the Solar Impulse 2 had finished 87 percent of its journey to Oahu, completing 4,439 miles of the 4,806-mile journey.

The plane has already set records.

At about 1 p.m. Wednesday, Solar Impulse 2 pilot Andre Borschberg broke an aviation record by spending 76 hours and 45 minutes in flight — the longest solo flight. The plane has also set the records for the longest solar-powered flight and the longest solo flight.

The sun is the only source of energy for the carbon-fiber aircraft. The plane’s 236-foot wingspan was built with more than 17,000 solar cells, four electric motors and lithium batteries replacing the need for fuel.

Hawaii will be the first of four U.S. destinations for the plane.

The Solar Impulse 2 will take off for Phoenix from Hawaii, and then make an as-yet-undetermined stop in the Midwest, followed by a landing in New York.

Since leaving Abu Dhabi, United Arab Emirates, in March, the plane has traveled to Muscat, Oman; Ahmedabad and Varanasi, India; Mandalay, Myanmar; Chongqing and Nanjing, China; and Nagoya, Japan.

The Solar Impulse 2 team provides updates of the plane’s progress at 808ne.ws/1H29dgp.

Updates from Borschberg are provided on Twitter through the pilot’s account @Andreborschberg. The Solar Impulse 2 team updates the plane’s progress through the account at @solarimpulse.