The pilot of the plane carrying the professional footballer Emiliano Sala was not licensed to fly the aircraft that plunged into the sea, killing both of them, an official report has concluded.

David Ibbotson had not completed night-flying training or recently practised instrument flying, a vital skill when piloting a plane on a dark night in poor weather, and the aircraft was travelling far faster than it should have been just before the accident.

Investigators concluded that Ibbotson was being paid to fly Sala even though under the terms of his private pilot’s licence this was not allowed, and said the regulations under which the light aircraft operated also meant it should have not been flown commercially.

The Air Accidents Investigation Branch (AAIB) concluded that the loss of control that led to the crash was made more likely by the fact that neither the pilot nor the plane had the required licences or permissions for the flight.

Investigators found such unlicensed “grey” flights frequently took place in the world of sport, business and leisure and called for more action to clamp down on them. The Civil Aviation Authority’s (CAA) investigation and enforcement team is continuing to carry out a criminal investigation into the accident.

Argentinian striker Sala, 28, was being flown from Nantes in France to his new club Cardiff City when the aircraft plunged into the English Channel on 21 January 2019. His body was recovered from the seabed 68 metres down.

In a statement, Sala’s family in Argentina said the report carried a huge amount of important technical detail. But they added: “The report leaves many questions for the inquest to address. It is crucial that the information held by the police and which went into compiling this report now be made available to the coroner and in turn to the family.

“Over a year has passed since Emiliano Sala died. His family remain distraught by their loss but determined to find the full truth of how and why he died, which requires the inquest to be held without delay.”

According to the report, Ibbotson, 59, from Lincolnshire, whose body has not been recovered, heard a “bang” or “boom” during the outward flight and “sensed” mist in the aircraft – but may have felt under pressure to make the return flight.

The report said: “Payment brings with it some pressures for a flight to be completed so that the fee will be paid and, perhaps, to realise the opportunity to secure work in the future.”

Investigators believe Ibbotson was probably suffering from carbon monoxide (CO) poisoning when the accident happened, possibly caused by a fault in the exhaust tailpipe that allowed gas to enter the cabin through the heating system.

The AAIB called for it to be made mandatory for planes to carry CO monitors – which it said cost as little as £15 but could tackle what they described as the “silent killer”.

Crispin Orr, chief inspector of the AAIB, said routine maintenance could not eliminate the risk of carbon monoxide leaks completely, but added: “Equipping aircraft with devices that provide warning of the presence of this odourless, colourless and lethal gas, would enable pilots to take potentially lifesaving action.”

On the issue of neither pilot nor aircraft having the correct licences, he said: “The chartering of aircraft that are not licensed for commercial transport – so called ‘grey charters’ – is putting lives at risk.”

The report found that Ibbotson was probably manoeuvring to avoid poor weather – heavy rain showers - just before the plane crashed. It descended rapidly towards the sea and at the last minute, the pilot tried to pull up, suggesting that he was still conscious. This attempted manoeuvre caused such stress that it caused a wing and the tail section to break away.

Investigators concluded that the plane was flying at 245 knots at the time of the accident – far above the 203 knots maximum speed allowed for the aircraft.

The report also said the autopilot had been diagnosed as having an intermittent fault. The autopilot was not engaged at the time of the crash but it has not been established if this was because it was not working or because Ibbotson turned it off.

On who organised the flight, the report says only that the arrangements were made by a “third party” – not Sala or the pilot.

A spokesperson for the CAA said: “The CAA’s investigation and enforcement team is carrying out a criminal investigation into the circumstances of the accident, the purpose of which is to consider whether any aviation offences have been committed. We will provide an update as soon we are able to do so.”

In a statement Cardiff City said the report raised a number of questions about “grey” charter flights.

The club said: “The report highlights a number of challenges the regulating bodies face in stopping grey charter flights, the widespread use of which in the football industry and more widely is placing countless lives at risk.”