A privately-funded search for the plane that was carrying missing Cardiff City footballer Emiliano Sala began on Sunday morning.
The Piper Malibu N264DB carrying 28-year-old Sala and pilot David Ibbotson, 59, disappeared over the English Channel on January 21 after leaving Nantes in France for Cardiff.
Marine scientist David Mearns, who is directing the privately-funded enterprise on behalf of the Sala family and claims to have located 24 major shipwrecks during his career, said he would be leading a team of seven other people on the vessel FPV Morven and it would be operating around the clock.
He said the the search is being carried out "in close co-ordination" with the Air Accidents Investigation Branch (AAIB).
As well as the vessel commanded by Mr Mearns, another commissioned by the AAIB has joined it in searching an area of around four square nautical miles north of Guernsey.
Mr Mearns said the AAIB has a "high confidence level" the plane could be in that zone but it could have moved once on the seabed.
The plane had requested to descend then lost contact with Jersey air traffic control.
An official search operation was called off on January 24 as Guernsey’s harbour master Captain David Barker said the chances of survival after such a long period were "extremely remote".
The AAIB was advised by its French counterparts on Monday that part of a cushion was found on a beach near Surtainville on the Cotentin Peninsula.
Cardiff had signed the Argentinian striker for a club record £15 million and he was due to start training last month.