The single-engine, propeller-driven aircraft disappeared over the English Channel after departing Nantes, a city in western France, at 8:15 p.m. local time on Jan. 21, headed for Cardiff, the capital of Wales.

Mr. Mearns, a maritime scientist, told the British broadcaster Sky News on Sunday evening that the vessel “was located earlier this morning by my crew onboard the Morven,” referring to the search ship FPV Morven. Mr. Mearns’s company, Blue Water Recoveries, had been collaborating with the British Air Accidents Investigation Branch, or A.A.I.B., scanning the sea floor using sonar.

A ship commissioned by the air accidents agency, the Geo Ocean III, launched a remotely operated vehicle, or R.O.V., to view the discovery at close range, the agency said in a statement on Monday.

“Based on analysis of R.O.V. video footage, the A.A.I.B. investigators on board the vessel concluded that the object is wreckage from the missing Piper Malibu aircraft, registration N264DB,” it said. The underwater drone “carried out a further search of the area overnight, but did not identify any additional pieces of wreckage.”

“Tragically, in video footage from the R.O.V., one occupant is visible amidst the wreckage,” the agency added, but it did not specify whether the body was Mr. Sala’s or Mr. Ibbotson’s. “The A.A.I.B. is now considering the next steps, in consultation with the families of the pilot and passenger, and the police.”