Solar Impulse 2, the solar plane attempting the first around-the-world flight without fuel, passed the halfway point to Hawaii from Japan Tuesday afternoon.

As of 4:22 p.m. Hawaii time, the Solar Impulse 2 had finished just over 50 percent of its journey to Oahu, or 2,412 of the total 4,806-mile trip.

The trip from Japan to Hawaii is the longest and most dangerous of the round-the-world venture.

Andre Borschberg, CEO of Solar Impulse 2, is piloting the plane alone for the five-day trip.

Borschberg and Solar Impulse 2 team members have been live-tweeting the flight by posting updates about Borschberg’s condition and the plane’s status.

Claudia Durgnat, spokeswoman for Solar Impulse, said Borschberg is in good health and the team at the Solar Impulse 2 Mission Control Center in Monaco is always watching the pilot.  

“There is always someone with him at the MCC. Even when he sleeps, they are there,” Durgnat said. “He is never alone, virtually.”

As of Tuesday, Borschberg had six of his eight oxygen tanks left, 12 of 18 food rations and 17 of 25 liters of water to help him complete the journey.

The plane is expected to arrive at Kalaeloa Airport in West Oahu, said the Solar Impulse 2 team.

After two failed attempts to travel to Hawaii, Borschberg successfully took off from Nagoya, Japan at 8 a.m. Sunday Hawaii time.

Hawaii will be the first destination in the United States for the plane.

Members of the Solar Impulse team arrived in Honolulu Tuesday afternoon to prepare to greet Borschberg when he lands. The team plans to stay two or three days in Hawaii for aircraft maintenance, a news conference and public visits.

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

The sun will be the only source of energy for the aircraft. The plane’s 72-meter wingspan was built with more than 17,000 solar cells, four electric motors and lithium batteries replacing the need for fuel.