Investigators looking into the crash of Swissair Flight 1-11 jet off Nova Scotia are still looking for critical pieces of the plane.

Eighty nine per cent of the aircraft has been recovered from the ocean floor off Peggy's Cove, near Halifax.

But parts of the forward section that might help explain a cockpit fire are still missing.

A barge with special vacuuming ability will be brought in over the next few weeks to sweep the seabed.

Investigators will the sift through the silt for debris.