Singapore Airlines has offered compensation of more than $15,000 for passengers who suffered minor injuries on flight SQ321, and an initial payment of $37,875 to those who were seriously hurt during severe turbulence.

One man died as a result of the incident in which scores of passengers and crew were flung into the roof of the Boeing 777-300ER when it struck severe turbulence en route from London to Singapore on May 21.

The flight then diverted to Bangkok to seek medical treatment for 79 injured passengers and six injured crew, out of a total of 229 people on board.

They included 56 Australians, of whom 13 were hospitalised.

Three weeks later, 20 people are still in Thai hospitals receiving medical care for broken bones, head and spinal injuries.

In a statement issued on Tuesday, Singapore Airlines said offers of compensation had been sent out to passengers, including a full fare refund for all concerned.

Those assessed as having minor injures were offered $15,150, and those requiring long term medical care were offered an advance payment of $37,875 to cover their immediate needs.

“This will be part of the final compensation these passengers receive,” the statement reads.

Singapore Airlines noted that as well as covering the medical expenses of the injured passengers, it had arranged for family members and loved ones to fly to Bangkok where requested.

Although the sums appeared significant, lawyers suggested it would be prudent for passengers to seek legal advice given the Montreal Convention allowed for significantly more compensation.

John Dawson of Vector Legal said the first tier of the convention permitted compensation of up to $257,000 for passengers who were physically hurt on airline flights.

The second tier allowed for unlimited damages, providing the carrier could not prove it was not negligent. Mr Dawson said in the case of SQ321, if the seatbelt sign was up, there may be a defence for Singapore Airlines.

“The damages are meant to be compensatory, that it’s supposed to reimburse the passengers for injuries and losses they have suffered,” Mr Dawson said.

“There is no compensation for psychological distress or harm.”

Director of Carter Capner Law, Peter Carter, said the payments being offered by Singapore Airlines were from the carrier’s insurer and their objective was to minimise the compensation bill.

He said the offer of $37,875 for seriously injured passengers to cover interim expenses was a “good move” but he doubted there was anyone on board who did not suffer an injury of some sort.

“The insurer should clarify if the $15,150 offer covers all passengers including those who endured the terror of the moment but were fortunate to escape physical injury,” Mr Carter said.

“All passengers should seek legal advice before signing anything with the airline. Those with any sort of injury should exercise extreme care and should be evaluated by their own medical specialists to determine how this accident might still affect them.”

He said it was Carter Capner’s “working theory” that the turbulence could have been avoided and “therefore some fault lies with Singapore Airlines”.