An American teenage solo sailor who went missing in rough Indian Ocean seas has been found safe and well with her vessel, her father told Australian media.

"She's fine, the boat's afloat and she's on it," Laurence Sutherland told public broadcaster ABC. "It's huge, fantastic, exciting news."

Fears had been raised for the 16-year-old girl attempting to sail solo around the world after her emergency beacons were activated and satellite communication was lost in the frigid southern Indian Ocean.

An international effort to rescue young Abby Sunderland, from Southern California, began, but the vast distances meant long hours of waiting for her family.

But her support team expressed confidence that she was alive because the beacons were deliberately turned on rather than set off automatically.

"She's got all the skills she needs to take care of what she has to take care of, she has all the equipment as well," said her brother Zac, himself a veteran of a solo sail around the world at 17.

Australian Maritime Safety Authority spokeswoman Carly Lusk said three vessels were sent from the French territory of Reunion Island, off Madagascar, and an aircraft was dispatched from Perth on a four-hour flight to Abby's location more than 2,000 miles from both Africa and Australia.

Qantas airlines said an Airbus A330 tasked by the safety authority took off at 7.53am today, Perth time, (12.53am BST) and its crew would try to spot the sailboat.

It was not clear when the surface vessels left, but it would take a day for the nearest ship to reach the area.

Support team member Jeff Casher said the two emergency beacons were continuing to broadcast and GPS location data showed they were together and drifting at 1mph. He believed the beacons were on Abby's boat but said they could be with her on a raft.

Conditions can quickly become perilous for any sailor exposed to the elements in that part of the world.

Abby last communicated with her family at 4am local time (noon BST) yesterday and reported 30ft swells, but was not in distress, Mr Pinkston said.

Abby left Cape Town, South Africa, on May 21 and on Monday reached the halfway point of her voyage.

On Wednesday, she wrote in her log that it had been a rough few days with huge seas that had her boat "rolling around like crazy".

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