Los Angeles, California (CNN) -- A 16-year-old California girl who is attempting to sail solo around the world triggered a distress signal during rough seas in the Indian Ocean on Thursday, her family said.
Abby Sunderland's family began scrambling to organize a search-and-rescue effort for her after they learned her emergency beacon was detected just an hour after they last spoke to her, according to Jeff Casher, an engineer on her support team.
Sunderland's small sailboat was adrift in the middle of the Indian Ocean about 2,000 miles east of Madagascar, 2,000 miles west of Australia and 500 miles north of the French Antarctic Islands, Casher said Thursday afternoon.
The government of Reunion -- a French island -- diverted a fishing boat toward her last known position, but it is not expected to reach the area until Saturday, Casher said. An Australian military ship, more than two days sail away, has also been dispatched, Casher said.
Friends in Australia have chartered an Airbus jet to fly over the area at sunrise Friday to see if Sunderland's vessel could be spotted from the air, he said.
Electronic signals from the boat indicate it is drifting at just a mile per hour, which means it is still afloat but not under sail, Casher said.
The mast might have fallen or Sunderland could have been injured, preventing her from sailing, he said.
Sunderland's father, who has been monitoring her journey from their Thousand Oaks, California, home, was emotional, but "he was trying to keep in positive spirits," according to Peter Thomas, a freelance journalist who spoke to Laurence Sunderland Thursday.
"Abby has all of the equipment on board to survive a crisis situation like this," her family said in a statement on their website. "She has a dry suit, survival suit, life raft, and ditch bag with emergency supplies. If she can keep warm and hang on, help will be there as soon as possible."
Sunderland began her journey from Marina del Rey, California, on January 23 with the goal of sailing her 40-foot boat around the world without stopping. Mechanical troubles forced her to make two stops for repairs, including at Cape Town, South Africa, in April.
She's kept in touch with family and followers through a satellite telephone. Her website has published frequent blog updates, including one posted Wednesday.
"The last few days have [been] pretty busy out here," Sunderland wrote in her last blog entry. "I've been in some rough weather for awhile with winds steady at 40-45 knots with higher gusts. With that front passing, the conditions were lighter today."
Sunderland is a "very determined" and "very capable sailor," Thomas said.
"She's pretty much unfazed by most everything, but she had been fatigued by this period of winds which she's been going through for several days now," he said.
When Abby's older brother Zac sailed around the world alone last year he became the youngest person to ever do so.
Australian Jessica Watson took over the distinction last month when she completed a non-stop solo circumnavigation just three days before her 17th birthday.
Abby has been on a schedule to complete her global journey about two months before her 17th birthday, which is on October 19.
CNN's Irving Last and Allison Blakely contributed to this report.