A pair of balloonists trying to fly to North America from Japan passed a major milestone Friday that could soon be declared a world record for length of time spent in the air by a gas-filled balloon, a spokeswoman said.

The feat came a day after the team of Troy Bradley, an American, and Leonid Tiukhtyaev, a Russian, logged what they also believe to be the distance record for such flights, flying more than 8,465 km by Thursday afternoon, according to the tracking website (www.pacificballoon.com) set up for their journey.

The existing distance record of 8,383 km set in 1981 also came on a trans-Pacific flight. The existing record for air time is 137 hours, set in 1978 by a trans-Atlantic team.

Bradley and Tiukhtyaev, who call their team and balloon Two Eagles, hope to land on the Baja Peninsula in Mexico on Saturday morning, spokeswoman Kim Vesely said. The pair took off for their trip on Jan. 24.

"The team is now fully focused on the final and most important task: landing the balloon safely after a successful crossing of the Pacific Ocean," she said.