Shipwreck hunter David Mearns and his team left St Peter Port Harbour in the early hours on board the Morven, which is equipped with sonar.
It has been joined by the Geo Ocean III, which is carrying out a joint search on behalf of the Air Accidents Investigation Branch.
Mr Mearns said yesterday that it would cover an area of two nautical miles square centred on the last position recorded for the aircraft on Guernsey Airport radar.
He told a press conference on the Crown Pier that in search terms the area to be covered was small but he stressed they were looking for a debris field as he did not think the aircraft was intact.
The search would be less complicated in summer but he was reasonably confident of success.
Sea conditions are good today.
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