He told media that the discovery had been so quick because the team had been looking for a static object rather than in a dynamic environment searching for survivors.
“No-one should walk away with the impression that the Coastguard and also the Channel Islands air search did anything other than a professional job,” Mearns said.
The AAIB said it expected to publish an interim report within the month.
Cardiff had signed Sala for a club-record £15 million and was due to start training last month.
It emerged on Wednesday that FC Nantes has demanded payment from Cardiff for the player’s transfer.
It is understood Cardiff received a letter from Nantes on Tuesday, in which the French Ligue 1 club threatened to take legal action if the first scheduled payment of the fee is not made within 10 days.
It is believed Cardiff were left surprised by the demand, considering the circumstances and the timing, and would rather the investigation into the tragedy was completed first.