The small aircraft disappeared over the English Channel on 21 January, travelling to Cardiff from Nantes, with authorities initially unable to find any trace of the plane, Sala or pilot David Ibbotson.
On Monday (AEDT), David Mearns – the coordinator of a privately funded search – confirmed a wreckage had been discovered, which was identified as the missing Piper Malibu plane.
A remotely operated vehicle (ROV) conducted a further search of the area overnight and the AAIB says footage shows one of the aircraft's occupants within the wreckage.
An AAIB statement read: "Having identified a priority search area last week, the AAIB agreed a search strategy with Blue Water Recoveries Ltd to maximise the chance of locating the aircraft wreckage.
"The AAIB commissioned specialist vessel Geo Ocean III and Blue Water Recoveries Ltd commissioned FPV Morven and the search area was divided between the vessels. Both vessels began their search on the morning of Sunday, February 3.
"Early in the search, the Morven identified an object of interest on the seabed using its side-scan sonar equipment.
"It cleared the immediate area for the Geo Ocean III to use its underwater remotely operated vehicle (ROV) to survey the area of the seabed in which the object was located.
"Based on analysis of ROV video footage, the AAIB investigators on board the vessel concluded that the object is wreckage from the missing Piper Malibu aircraft, registration N264DB.
"The 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 is now considering the next steps, in consultation with the families of the pilot and passenger, and the police.
"The image shows the rear left side of the fuselage including part of the aircraft registration. We intend to publish an interim report within one month of the accident occurring."
Prior to Sunday, the previous significant update from the AAIB had come when seat cushions thought to be from the plane were found on a beach in northern France on Wednesday.
It is 11 days since Guernsey Police ceased looking for the aircraft, which was carrying Sala, 28, back to Cardiff after he had said goodbye to former team-mates at Ligue 1 side Nantes.
Initial search and rescue efforts proceeded for three days before authorities opted to call a halt to their scanning of the area.
Guernsey harbourmaster Captain David Barker called their chances of survival "extremely remote", but a number of high-profile football figures and members of the public answered the family's calls to fund a private search operation that has been headed up by Mearns.