There are calls from aviation experts to investigate a number of flights organised in the weeks leading up to the fatal crash that killed Emiliano Sala.
A series of 12 journeys between the United Kingdom and France — carrying Cardiff City officials and football agents — were made during negotiation of the deal that took Sala from Nantes to Cardiff City in January.
The Air Charter Association (Baca) are concerned about whether those journeys broke regulations and have recommended the Civil Aviation Authority investigate them.
Argentine striker Sala, who had just signed for Cardiff from Nantes in a club record £15million transfer, died when the Piper Malibu aircraft that was taking him to his new club crashed into the English Channel on January 21. Pilot David Ibbotson, who was also on board, has not been found.
The Air Accident Investigation Branch is currently investigating the flight.
Questions have been raised about who owned the aircraft and the fact Mr Ibbotson did not hold a commercial pilot's licence. Agent Willie McKay has admitted to booking that flight and several others.
Dave Edwards, chief executive officer of Baca, says there have long been major concerns in the aviation industry about illegal charter flights and believes there are more questions to be asked about the journeys in the build-up to the Sala tragedy.
"The football agent has said on the record that they paid for a series of flights," Mr Edwards said.
"We've done some background research into all of those flights and we're concerned more than ever that all of them have the potential to have, certainly, questions to be asked about them, which is what we've pushed the CAA (Civil Aviation Authority) to be doing recently and also Easa (the European Union Aviation Safety Agency) because the origin of the flight was in France so that comes under (their) territory.
"There's enough circumstantial evidence here that would make us push the authorities to do a full investigation into the background to ensure it was compliant.
"We don't have any proof at this stage. All we're asking is the CAA do everything in their power to investigate the legal state of those flights.
"This is the tip of the iceberg of the story in terms of flights like this. It happens all the time and the CAA must do something about it."
The AAIB has published an initial report that confirmed Mr Ibbotson didn't have a commercial pilot's licence.
Mr Edwards explained that means Mr Ibbotson would not be allowed to receive any money for the journeys.
He added: "The only way you can do it is cost-share between everyone, or by a lease. But since the plane was registered in the US like many of the planes used by Willie McKay, only a US citizen can lease it.
"All of these flights are filed with Eurocontrol (Europe's main air traffic organisation) as General Aviation flights, non-commercial, and no money can be received for them."
Willie McKay confirmed in a national TV interview last month that the flight was not arranged on the basis of "cost-sharing"
Baca has produced a timeline of 12 flights organised by McKay in the lead-up to the Sala deal. They include flights carrying Neil Warnock, his assistant Kevin Blackwell, Cardiff player liaison officer Callum Davies, Sala and his personal representative Meissa N'Diaye, as well as McKay and his son Mark.
It reveals the journeys made between Cardiff, Paris, Stapleford and Nantes used three different companies. None of them were linked to David Ibbotson or David Henderson, the man McKay says he organised the fatal flight with.
Warnock and Blackwell first went to Nantes to watch Sala play — and score — against Marseille on December 5.
Warnock then revisited Nantes with the McKays and Mr Davies on January 8, before Sala and his agent Mr N'Diaye came to Cardiff on January 14 to meet Warnock and other Bluebirds officials and take a look around Cardiff City Stadium.
The pair then flew back in time for Sala to represent Nantes for the final time, against Nimes on January 16.
The striker then headed for Cardiff once more to agree the deal on January 18 — which was announced by the Bluebirds on January 19 following their 3-0 defeat to Newcastle — before returning to Nantes and boarding the fatal flight on January 21.
