The pilots of a helium-filled balloon on a daring flight across the Pacific Ocean drew closer to North America as they attempt to break two world records.

Accomplished balloon pilots Troy Bradley of Albuquerque and Leonid Tiukhtyaev of Russia are expected to cross into North America sometime Thursday evening and are on course to break a distance record that has stood for more than three decades. They're also looking to break the flight-duration record set in 1978.

They still have a ways to go before completing the journey, however. They are planning to cross over the Canadian Rockies and land somewhere in the northern U.S., possibly Montana or North Dakota, on Saturday morning.

No one has crossed the Pacific Ocean in a gas balloon since 1981. But to break the distance record, the balloonists need exceed the current records by 1 percent to claim a new world record. That means they need to travel 5,260 miles to break the mark.

Another important record is the duration of the flight, set in 1978 when Ben Abruzzo, Maxie Anderson and Larry Newman made the first trans-Atlantic balloon flight. That record of 137 hours in the air in a traditional gas balloon is considered the "holy grail" of ballooning achievements. The pilots on the current flight are at about 100 hours.

If they get that far, the team will notify the National Aeronautics Association of its claim within seven days of landing and all the documentation will be forwarded to the Federation Aeronautique Internationale for consideration. The process can take weeks, but the team will have plenty of data to present since the balloon is outfitted with an array of monitors and other instruments.

In a visible sign of the progress, the tracking monitors at mission control in Albuquerque switched to showing U.S. cities as the closest landmarks Wednesday.

"That just made it very real that we're getting close," team member Kim Vesely said.

But not even the pilots know where they will land. It depends on the winds encountered along the way.

The balloon's speed has slowed significantly, which is something forecasters had expected. The balloon, made up of a massive envelope and a specially-designed carbon fiber-composite capsule, is capable of staying aloft for as many as 10 days.

The team says the very last task will be a safe landing. Since there's no certainty about where the balloon will touch down, the head of the recovery effort has established a network of balloonists across the U.S. and in southern Canada who can serve as chase crews, those who are on the ground to help with tethering the capsule and rounding up the balloon's envelope as it deflates. The volunteers are ready to travel within a 200-mile radius once the landing spot becomes clear.