A British Airways co-pilot who believed he had been poisoned by contaminated cockpit air died from an unintentional overdose of sedatives, a coroner has ruled.
Richard Westgate, 43, died in 2012 after moving to the Netherlands to seek help from a specialist clinic for his symptoms which he thought were caused by "aerotoxic syndrome", which has been called "pilot's disease".
The air industry disputes that any such condition exists.
Mr Westgate's family said he suffered from various symptoms, including digestive problems, fatigue, general pain, headaches, loss of cognitive ability, clumsiness and inability to sense temperature.
Coroner Dr Simon Fox QC recorded a conclusion of accidental death following a week-long inquest in Salisbury.
At the start of the inquest, he ruled that aerotoxic syndrome would not be treated as a factor in Mr Westgate's death.
Mr Westgate's family said the family would keep campaigning over "toxic air" on planes. They vowed "One day the truth will out" in a statement read out by his mother Judy.
The family accused the air industry of deliberately failing to acknowledge a condition which they said would ultimately be likened to tobacco companies refusing to admit that smoking causes cancer.
"The airlines cannot categorically say that air in these aircraft is safe. They refuse to monitor and test for toxins, so of course they have no evidence because they will not look for it," they said.
"The longer they deny there is a problem, the harder and more costly it's going to be when they are proved wrong.
"Just like the tobacco industry in the Fifties refusing to admit smoking causes cancer, the airline industry has its head in the sand."
Neuropathologist Dr Daniel du Plessis had told the inquest he found evidence that Mr Westgate had been suffering from neuritis - inflammation of the nerve roots .
The condition could explain many of these symptoms, including pain, tingling sensations, numbness and balance problems, he said.
Dr du Plessis said organophosphate poisoning - the supposed cause of aerotoxic syndrome - could cause nerve problems but not the nerve inflammation suffered by Mr Westgate.
He added that a more likely explanation for Mr Westgate's condition was an autoimmune condition such as Sjogren's syndrome, which causes the immune system to start attacking healthy cells and tissues.
The family maintain that airborne toxins inside planes can cause damage to the nervous system and heart.
"We know there are more sick passengers and crew and we hope today will encourage the millions who fly to ask questions to ensure more is done to make sure others don't suffer like my son," said Mrs Westgate.