A Sydney man is suing British Airways for up to A$600,000 after he was forced to endure a long-haul flight from London to Shanghai in a broken seat, a court has heard.

Richard John Pattison, 64, sustained an injury to his neck after he had to remain upright for the entire 12-hour flight when his seat would not recline past its "take-off" position.

The engineer from Concord told the court that during the flight in September 2006 he woke several times to his head "snapping back" after it had fallen forward because of the awkward angle of the seat.

When he complained to airline staff he was told he could not be moved because the flight was full, the court heard.

Mr Pattison, who had been on a business trip at the time of the injury, is suing British Airways for damages, including economic losses that stemmed from the incident.

As a result of his injuries he had to employ more workers and alter his hours of work as chief executive of a plastics manufacturing company, the court heard.

This included sometimes having to send work emails at 3am.

Did you find this arrangement satisfactory?" asked his counsel, Martin Luitingh.

"No," he replied. "It is tiring, it is no life and I'm married."

Mr Pattison told the court his neck had been stiff as he walked off the flight but it was not until he woke from a seven-hour sleep after arriving at his hotel that he began to experience excruciating pain. He could not raise his head from the pillow without assistance and it was too painful to lift his left arm above his waist, the court heard.

A specialist who prepared reports on Mr Pattison's injury, James Bodel, told the court there was a causal link between the flight and Mr Pattison's pain.

Dr Bodel said Mr Pattison also had a pre-existing arthritic condition, consistent with ageing, which made his spine "vulnerable" to such injuries.

"It is a very unnatural way to sit in a confined space for a very long period of time without trying to fall asleep," he said. "Economy [class] is not a very good place to be if you want to enjoy yourself."

British Airways denies it is liable for Mr Pattison's injuries, claiming he failed to use a pillow to support his neck and did not adopt an "ergonomically suitable position" during the flight.

Counsel for the airline, Des Fagan, SC, asked Mr Pattison why he had sent a letter of complaint to the airline shortly after the flight which claimed the seat would not recline because there was a storage canister behind it.

"That was my theory at the time," Mr Pattison said. "Since then I have seen some information from British Airways that says the seat will recline with the canister there.''

Mr Fagan said: ''The other position, Mr Pattison, is that your account here today of having asked an attendant to help you and [that] the attendant was not successful, was a lie."

"I don't tell lies," he replied.

The hearing, before Judge Garry Neilson, continues.