One passenger died of a heart attack and another 30 were injured when Singapore Airlines flight SQ321 encountered severe turbulence early Wednesday morning.
The plane was en route from London to Singapore, but had to make an emergency landing in Bangkok.
Although turbulence is common in air travel, incidents like this involving severe turbulence are rare.
What happened to flight SQ321?
The plane hit an air pocketAs cabin crew served breakfast, Suvarnabhumi Airport director Kittipong Kittikachorn told a news conference.
The country experienced what is classified as "severe turbulence" while over southern Myanmar.
Tracking data from FlightRadar24 shows the flight flew at an altitude of 37,000 feet (11,277.6 meters) - which is within the average cruising range of commercial flights.
Then around 7:49 am Boeing 777-300ERsuddenly and sharply dropped 75 feet (22.86 m) in three seconds before flying up 200 feet (60.96 m) in six seconds.
It continued to fall and within seconds flew up several hundred meters,reached a maximum of 37,400 feet (11,399.52 m) at 7:49:59 before immediately descending 400 feet (121.92 m) in about 26 seconds.
Ofthe entire ordeal lasted just under a minute and a half.
This graph shows the altitude of the flight during this period according to FlightRadar data.
About 15 minutes later it startedstandard descent for about three minutesto a new cruising altitude of31,000 feet (9,448.8 m).
FlightRadar24 said the flight may have continued to experience turbulence during descent, but it was not an air pocket event.
It remained at that altitude for about eight minutes.
It landed in Bangkok less than half an hour later at around 8:45 am.
What is 'severe turbulence'?
It is the second highest category on the turbulence intensity scale.
The Australian Civil Aviation Safety Authority (CASA) lists six categories of turbulence:
- 1.Leave right:Light, fast and some rhythmic bumps without significant changes in aircraft altitude or attitude
- 2.Light turbulence:Small, irregular changes in aircraft altitude and/or attitude. Occupants may feel a slight strain on the seat belts. Unsecured items may be moved slightly. Cabin service is available and there are few or no walking problems
- 3.Moderate rights:Rapid jerks or jerks without noticeable changes in aircraft altitude or attitude
- 4.Moderate turbulence:Changes occur in the altitude and/or attitude of the aircraft, but the aircraft remains under control at all times. It usually causes variations in the indicated airspeed. The occupants clearly feel tension on the seat belts; unsecured objects are released; and cabin service and walking is difficult
- 5.Serious:Large, abrupt changes in aircraft altitude and/or attitude. Usually causes large variations in indicated airspeed. Airplanes can temporarily go out of control. The occupants are forcibly forced into the seat belts; unsecured objects are thrown around; and cabin service and walking is impossible
- 6.Extreme:Airplanes are thrown around violently and are virtually impossible to control. May cause structural damage
How common is severe turbulence?
"Extremely rare" explains Steve Cornell, pilot and safety and technical director at the Australian and International Pilots Association.
“In my 15,000 hours of flying experience, I have only encountered severe air turbulence once, so it is rare.”
What causes turbulence?
Here's how CASA explains it:
“Turbulence is caused by the relative movement of disturbed air through which an aircraft flies and is responsible for the abrupt lateral and vertical jolts that passengers may experience during flight.
“Its origin may be thermal or mechanical, and it may occur within or without clouds.”
Can turbulence be predicted?
Crews plan ahead by studying turbulence and other weather forecasts that have improved over the years, loading extra fuel when necessary and monitoring weather radar during flight.
Only sometimes,Severe turbulence in clear air leaves crews little time to respond.
"If it's unexpected, then it's a bit late," said retired pilot Hugh Dibley, an expert on aircraft failures at the Royal Aeronautical Society.
“You hope to get warnings from other aircraft in the area and slow down to make sure the effects are minimized,”
NASA says it is developing an early warning system that relies on ground-mounted infrasound microphones to detect clear-air turbulence hundreds of miles away.
Austrian tech startup Turbulence Solutions says it is developing technologies to eliminate up to 80 percent of turbulence.
But industry experts warn that all new aircraft systems must be proven to operate at a high level of reliability, requiring years of rigorous testing before the technology can be validated. Airlines usually have to agree to pay the bill for any upgrades.
Why was it so sudden?
Aviation expert Keith Tonkin told ABC News Breakfast that while turbulence can usually be predicted, it appears it was not expected.
“A lot of effort goes into predicting weather conditions around the world, and most of the time it is quite accurate,” he said.
“But there is no absolute certainty that we know what we will encounter from time to time.”
He said that for some reason the pilot did not expect the turbulence and they were unwilling to force the passengers to buckle up.
“There were people walking around eating their breakfast and a lot of people apparently weren't wearing their seat belts,” he said.
He said an investigation would provide more clarity.
Loading...
Is it safe to fly in turbulence?
As for their structure,all modern commercial aircraft are built to handle itwith forces many times greater than those during flight, said Paul Hayes.
Turbulence of this severity is rare.
But according to Swedish turbulence forecasting website Turbli, passengers' feelings vary from plane to plane and seat to seat.
Long flights can feel most turbulent at the rear, and the ideal spot is around the center of gravity, which is usually just forward of the wings.
Boeing's high-tech 787-9, with a "Gust Alleviation System" from Honeywell HON.N, ranks first in handling turbulence, according to Turbli.
Next up is the Airbus A340-500/600, although this four-engine model is no longer widely used due to fuel costs.
The Boeing 777 family is believed to have a strong safety record, with the exception of Malaysia Airlines MH17, which was shot down by a missile over Ukraine, and the mysterious disappearance of MH370, both in 2014.
It is equipped with traditional weather radar, but does not have the relief system of the newer 787.
Keith Tonkin fortalte News Breakfast detthe larger the plane, the less turbulence you would feel.
“So this is a relatively important event,” he said.
“You can imagine that a smaller Cessna-type aircraft would have been more affected.”
What does this mean for seat belts?
Tonkin said the incident highlighted the importance of wearing a seat belt when sitting.
“That's why we always say that when you're in the cab, you should wear your seat belt so that you're ready if something like this happens,” he said.
Among those most at risk of injury are the crew, who must walk around the cabin to check that seat belts are on when the signs come on.
Is climate change to blame?
A wave of turbulence reports has sparked a debate over whether climate change could cause more turbulence.
A report from the University of Reading last year suggested that the turbulence could be worsened by climate change.
“Our latest future projections indicate a doubling or tripling of severe jet stream turbulence in the coming decades if the climate continues to change as we expect,” said Professor Paul Williams, one of the authors.
However, he told Fox News that while there appeared to be a strong link, more research was needed.
“It is too early to definitively blame climate change for the recent apparent increase in turbulence. Increased media coverage, aided by video footage from passengers' mobile phones during the flight, could be a factor,” Williams added.
ABC/wires
Were you on Singapore Airlines flight SQ321 or do you know someone who was? Let us know by completing the form below.
Loading...
Posted,Topical
