Cardiff have also conducted an internal investigation that the Telegraph has been told has found no evidence pilot Dave Ibbotson held the licence necessary to carry passengers on a commercial basis.
Senior figures believe, if the AAIB confirms Ibbotson was not qualified for the trip, that would constitute negligence on the part of whoever recruited the part-time gas boiler engineer.
They also believe liability for that could be extended to cover Willie and Mark McKay – who admitted arranging Sala’s flight but not selecting the plane or pilot – and, in turn, Nantes, for whom the duo had been working.
A successful negligence claim against the French club would slash the transfer fee owed to them for the player, the withholding of which they have threatened legal action over.
Cardiff could attempt to reduce the figure further by arguing the change of ownership of Sala was incomplete when he died because he had yet to be registered to play in the Premier League.
Chairman Mehmet Dalman told the Telegraph: “We believe that the player was not registered with the Premier League.”
It can also be revealed that Cardiff broke their transfer record to sign Sala despite major concerns about the deal at boardroom level.
More than one source has told this newspaper that City’s four-man transfer committee was split over buying the striker, with a vote ending 3-1 in favour of doing so.
When asked by the Telegraph about the split, Dalman said: “I really don’t think it is appropriate for me to comment at this stage but your line of enquiry is not necessarily wrong!”