By Kokkai Ng and Joseph Campbell

SINGAPORE, May 22 (Reuters) - Many passengers on a

Singapore Airlines flight hit by heavy turbulence

which left dozens injured and one dead from a suspected heart

attack finally reached Singapore on Wednesday morning.

Dozens of passengers quietly filed off a Singapore Airlines

jet, mostly ignoring media awaiting their arrival. Some

responded to shouted questions, confirming they had been on the

original London-Singapore trip and saying "Good flight!" when

asked about the last leg from Bangkok.

The scheduled London-to-Singapore flight diverted to Bangkok

after the plane was buffeted by turbulence that flung passengers

and crew around the cabin, slamming some hard into the ceiling.

A 73-year-old British passenger died of a suspected heart

attack and at least 30 people were injured. Singapore Airlines

took those who could continue on a flight from Bangkok that

reached Singapore just before 5 a.m. (2100 GMT).

Singapore's Transport Safety Investigation Bureau (TSIB)

is looking into the incident, and the U.S. National

Transportation Safety Board is also sending representatives for

support.

The sequence of events is still unclear, as the plane

declared a medical emergency - but Reuters has not been able to

confirm whether that happened before the turbulence erupted and

the plane's altitude dropped from 37,000 feet to about 31,000

feet in a short period of time.

The sudden turbulence occurred over the Irrawaddy Basin in

Myanmar about 10 hours into the flight, the airline said.

Turbulence has many causes, most obviously the unstable weather

patterns that trigger storms, but this flight could have been

affected by clear air turbulence, which is very difficult to

detect.

Turbulence-related airline accidents are the most common

type of accident, according to a 2021 NTSB study.

Photographs from the interior of the plane showed large

gashes in the overhead cabin panels, oxygen masks and panels

hanging from the ceiling and items of hand luggage strewn

around. A passenger said some people's heads had slammed into

the lights above the seats and punctured the panels.

"Some people hit their heads on the baggage cabins overhead

and dented it, they hit the places where lights and masks are

and broke straight through it," Dzafran Azmir, a 28-year-old

student on board the flight told Reuters.

While the airline said 30 people were injured, Samitivej

Hospital in Thailand said it was treating 71 passengers.

From 2009 through 2018, the U.S. agency found that

turbulence accounted for more than a third of reported airline

accidents and most resulted in one or more serious injuries, but

no aircraft damage.

Singapore Airlines, which is widely recognized as one of the

world's leading airlines and is a benchmark for much of the

industry, has not had any major incidents in recent years.

Its last accident resulting in casualties was a flight from

Singapore to Los Angeles via Taipei, where it crashed on Oct.

31, 2000 at the Taiwan Taoyuan International Airport, killing 83

of the 179 people on board.