The pilot of the plane carrying Cardiff City striker Emiliano Sala was not qualified to fly at night, it has been claimed.
David Ibbotson was at the controls of the aircraft on its way to South Wales from France when it lost contact from radars.
After an extensive search, the body of Sala was recovered but that of Mr Ibbotson is yet to be found.
Ibbotson is thought to have been colour blind which prevents pilots from attaining a licence to fly at night, report the BBC.
An aviation source told them: "Colour-blindness stops a pilot from obtaining a night rating straight away, because being able to differentiate between green and red lights is key to flying in the dark.
"Anything that's on the UK licence applies to the US licence as well, so he couldn't do anything more than the UK licence allows.
"Flying outside the restrictions of your licence is illegal and that's likely to affect the insurance cover for the flight."
Sala had completed a club-record move from Nantes to Cardiff and had travelled back to his former club to say his goodbyes to teammates and staff.
Cardiff 'to tell FIFA they will not pay Emiliano Sala transfer fee'
The flight back to the Welsh capital was delayed until the evening at the request of Sala.
It has been recently reported in the Telegraph that the Bluebirds are ready to tell FIFA they will not pay the £15million fee for Sala, claiming the striker's death makes the transfer "null and void".
