The AAIB said it was considering its next steps in consultation with the police and families of Sala and the pilot David Ibbotson.
Underwater searches using specialist vessels uncovered an “object of interest” on the seabed on February 3, according to the investigators.
A remotely operated vehicle surveyed the area and, based on analysis of the video footage, investigators concluded that the object was wreckage from the missing Piper Malibu aircraft.
In a statement issued on Monday, the AAIB said: “The remotely operated vehicle (ROV) carried out a further search of the area overnight, but did not identify any additional pieces of wreckage.
“Tragically, in video footage from the ROV one occupant is visible amidst the wreckage.”
The AAIB added that the image showed the rear left side of the fuselage — the main body of the aircraft — and part of the registration.
“We intend to publish an interim report within one month of the accident occurring,” it said.
Cardiff City’s record signing
The Argentine striker had recently signed with English Premier League club Cardiff City for a reported £15 million ($19.3 million) from French club Nantes and was heading to the Welsh capital after saying farewell to his former teammates in France.
On Sunday, the AAIB had also begun a three-day underwater search of an area four square nautical miles off the island of Guernsey.
David Mearns, a marine scientist leading the private search team hired by Sala’s family, said the wreckage of the plane had been located by sonar equipment at a depth of about 63 meters within the first couple of hours of starting Sunday’s search. Experts on the larger vessel — Geo Ocean III — used by the air investigators confirmed it was the missing Piper Malibu aircraft.
Speaking on BBC’s Today show, Mearns said the wreckage was surprisingly intact and added that the family would “desperately” like the plane to be recovered.
“The next step is down to the the AAIB,” he said Monday, before air investigators had released their statement.
“They had contracted the vessel they are using, the Geo III, for three days. They wouldn’t be able to recover it in that period of time but that’s probably what they’re evaluating.
“If they can dive today [Monday], the weather’s not great today, then hopefully they’ll get some more information about how they would attempt that recovery.”
In revealing he had been in touch with Sala’s family and agent, Mearns added: “They felt they have done beyond what any sort of normal family would have ever done in raising this money to conduct a privately funded search to go out there and get this result so quickly and now they feel it’s the responsibility of the government to take the next step.”
On January 30 seat cushions believed to be from the missing plane were found on a beach near Surtainville, on the northwest coast of France.
Speaking publicly on January 28 for the first time since it emerged that Sala was on board the plane, Cardiff manager Neil Warnock said he had considered retiring during “by far the most difficult week in my career by an absolute mile.”