An aviation lawyer is questioning whether Singapore Airlines is at fault after its flight from London hit turbulence that caused a man’s death and critical injuries to many other passengers.

Flight SQ321 encountered turbulence on May 21 and diverted to Bangkok. Of the 211 passengers and 18 crew on board, 23 of them were New Zealanders. 79 passengers and six crew were taken to hospital.

Director of Carter Capner Law, Peter Carter, representing injured passengers on the flight, said preliminary findings released last week by the Transport Safety Investigation Bureau of Singapore raised a number of issues that point to possible fault by the airline.

He said these include possible failure to take the normal precautions to avoid an obvious and large area of thunderstorms and the failure to alert passengers to fasten seat belts.

“It’s looking likely that this is not a simple case of unexpected turbulence,” Carter said.

He explained that compensation is a key reason why the airline may be keeping quiet, as if the airline was not at fault, the Montréal 1999 Convention capped passenger claims at US$175,000.

However, if there was any degree of fault by an airline’s pilots or engineers, there is no limit to a compensation claim.

The TSIB’s preliminary report, based on initial analysis of the flight data recorder and cockpit voice recorder, stated the plane was “likely flying over an area of developing convective activity.”

Carter, who is also representing passengers on LATAM Airlines flight LA800 that plunged in March, is focusing his investigation on whether the Singapore Airlines event was associated with thunderstorms developing close to the aircraft’s flightpath.

“The cockpit voice recorder will answer questions about the attention the air crew was paying to developing thunderstorms including whether they were even checking the weather radar.

“Furthermore, despite a suggestion from the airline that a return to seat announcement had been made and the seatbelt sign illuminated prior to the incident, passengers we represent tell us there was no seatbelt warning at all, and that service by the flight attendants was proceeding normally.”

The TSIB said before passengers were thrown into the air, “it was heard that a pilot called out that the fasten seat belt sign had been switched on.”

Carter said while he acknowledged the ongoing investigation, he wanted Singapore Airlines to publicly answer why the aircraft didn’t divert to avoid the risk of thunderstorms and was there a discussion about doing so, how long before the incident was the weather radar monitored and the experience of the flight crew.

Carter said turbulence and in-flight upsets are now the leading causes of airline cabin injuries, far exceeding the number of injuries caused by other accidents such as impact with terrain.

In New Zealand, a Jetstar flight from Auckland to Dunedin had to turn back on Saturday after running into “significant turbulence.” There were no injuries.

More than a third of all airline incidents in the United States from 2009 through 2018 were related to turbulence and most of them resulted in one or more serious injuries, the National Transportation Safety Board reported.

NTSB figures also show that between 2009 and 2022, 163 people were injured seriously enough during turbulence events to require hospital treatment for at least two days.

Research by the Department of Meteorology at the University of Reading, and the UK Meteorological Office says clear-air turbulence has increased over the past four decades with severe-or-greater clear-air turbulence becoming 55% more frequent in 2020 than 1979.

A Qatar Airways flight was also hit with turbulence between Doha and Dublin, resulting in 12 injuries, just a week after the Singapore Airlines flight.

Carter said these events will likely lead to more compensation payouts.

“Access to passenger compensation above the first-tier limit may depend on demonstrating how far the aircraft was from developing thunderstorms in an effort to show aircrew ought to have implemented a flightpath diversion,” he said.

NIWA research meteorologist Richard Turner told Stuff Travel thunderstorms can be seen visually or on a plane’s weather radar system.

“One of the problems with some turbulence is that they don’t get much warning at all. It’s clear air turbulence that they can be actually hard to detect, but a thunderstorm I would have thought that there would be some sort of visual warning, but if you’re flying overhead and it’s sort of developing beneath then that could be a bit tricky.”

Emirates is adding turbulence detection tools to 140 aircraft with software that automatically shares turbulence reports among all airlines contributing to the International Air Transport Association’s information-sharing platform.

The TSIB’s investigations are ongoing and as a result Singapore Airlines said it was unable to provide further details.