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
Sala, 28, and the 59-year-old Ibbotson were flying in the single-turbine aircraft from Nantes, in northern France, to Cardiff in Wales, when it disappeared from radar near the Channel Islands on January 21.
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.
Wreckage from the plane thought to be carrying the footballer was found Sunday by a privately funded search team working in close coordination with the AAIB.
On Sunday, the AAIB had also begun a three-day underwater search of 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 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.”
The official search operation was called off on January 24 after Guernsey’s harbor master, Captain David Barker, said: “the chances of survival at this stage are extremely remote.”
That decision prompted tearful pleas from Sala’s family, who urged officials to “use all means possible” to find out what happened to the plane that had requested descent on passing Guernsey, but disappeared from radar at about 2,300 feet.
The private search mission was financed through a crowdfunding campaign, with French World Cup star Kylian Mbappe among the footballers donating to the initiative.
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.
Last week, Cardiff City and Nantes both held emotional tributes to Sala before their matches.
Nantes manager Vahid Halilhodzic was reduced to tears when play was briefly stopped in the ninth minute — Sala’s squad number — of Nantes’ Ligue 1 match with Saint-Etienne.
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.”