Babar Suleman and his Haris, 17, stand next to their plane at an airport in Greenwood before taking off on their round-the-world flight. Picture: Robert Scheer, The Indianapolis Star

Pago Pago, American Samoa -

A man who saw a plane flown by a US teenager seconds before it crashed and killed the boy and his father during an around-the-world flight attempt said the aircraft was flying low, but didn't show any obvious signs of distress before diving into the ocean off American Samoa.

Bert Thompson of Matuu, American Samoa, told The Associated Press on Thursday he saw no fire, explosions or emergency lighting on the plane carrying 17-year-old Haris Suleman and his father, 58-year-old Pakistani-born Babar Suleman.

“It just went down, dived into the ocean,” said Thompson, who saw the plane while sitting at a bus stop in his shoreline village.

Haris Suleman's body was recovered shortly after Tuesday's crash. Crews were still searching for his father.

Thompson said he didn't see the plane hit the water because it was too far offshore and too dark, with no moon in the sky.

Anguished family members and friends pleaded for more resources on Thursday in the hope of finding Babar Suleman.

“Time is of the essence,” family friend Azher Khan said at a news conference outside the family's home. “Babar is a fighter, and I know that he's over there clinging to hope, hoping that someone will come for rescue.”

The US Coast Guard said on Thursday it had found wreckage from the plane, which crashed shortly after taking off from Pago Pago, American Samoa.

A pilot spotted sections of the plane's fuselage and other aircraft components on Wednesday night, spokesman Gene Maestas said, and ships later recovered some of that debris.

Divers searching for Babar Suleman went to the last known location of the plane's distress signal but found the 100m water too deep, said American Samoa Homeland Security Department Director Iuniasolua Savusa.

“It's beyond their capabilities at this point,” Savusa said. “So right now, we are doing all we can to deploy methods we have on island.”

That includes casting a net to the bottom of the ocean and dragging it to see if it captures any wreckage.

Haris Suleman had hoped to set the record for the fastest circumnavigation around the world in a single-engine airplane with the youngest pilot in command. His journey was also a fundraiser to help build schools in Pakistan.

Babar Suleman had long dreamed of flying around the world. The Sulemans left the US on June 19 and had been expected to arrive back on Saturday.

Family and friends defended the father-son team and their mission, saying they had known the dangers when they set out and had trained for them. - Sapa-AP