Sydney to Hobart yacht race competitors fished aviation headphones and an aircraft headrest out of the sea near where a light plane crashed into water in southeast Tasmania.
Two men - a 29-year old pilot and a 61-year-old photographer - were on board the single-engine Cessna when it plunged into waters off the Tasman peninsula about 6.20pm on Monday.
They had been taking photos of race yachts on the approach to Hobart.
Police commander Tony Cerritelli said the plane was flying in less than ideal weather conditions and was just 300 metres from a race competitor when it went down.
"It was flying at around mast level and plunged nose-first into the water," he said on Tuesday.
Race competitor Mistraal radioed for help as it rushed to where crew members saw the plane's tail disappear beneath the waves.
An oil slick has been found in the area and there is still oil coming to the surface, marine rescue services inspector Lee Renshaw said.
A few "unique" items have also been retrieved.
"It's a headrest, a set of headphones and a cover off one of the earpieces on aviation headphones with a boom microphone," Insp Renshaw said.
However, there has been no sign of the plane or the men as an extensive search continues.
Waters in the area are up to 90 metres and too deep for divers.
Police boats are using sonar and Insp Renshaw insisted the operation remains a search, not a recovery operation.
"We are pretty confident we can pinpoint the location of the aircraft."
The seven race yachts which detoured to assist in the search for the plane were praised by Cruising Yacht Club of Australia commodore John Cameron.
"An ocean race is of secondary importance to the safety of people and at the moment, we are all thinking of those affected by this event," he said at the Hobart waterfront
Tasmanian Premier Will Hodgman also commended the quick-thinking crew members.
"The mayday call from Mistraal enabled emergency personnel to get to the area quickly," he said.
A police boat was on the scene within 25 minutes.
