Emirates A388 near Chennai on Jul 10th 2019, turbulence injures passengers and crew

Last Update: August 27, 2020 / 16:09:44 GMT/Zulu time

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Incident Facts

Date of incident
Jul 10, 2019

Classification
Accident

Flight number
EK-449

Aircraft Registration
A6-EEM

Aircraft Type
Airbus A380-800

ICAO Type Designator
A388

An Emirates Airbus A380-800, registration A6-EEM performing flight EK-449 from Auckland (New Zealand) to Dubai (United Arab Emirates) with 378 passengers and 29 crew, was enroute at FL400 about 140nm east of Chennai (India) at around 21:54Z when the aircraft encountered turbulence. The crew continued the flight for a safe landing in Dubai about 3 hours later. One passenger received serious, 13 passengers and 13 crew minor injuries. An unknown number of passengers were taken to hospital.

The airline reported a few passengers and crew received minor injuries when the aircraft encountered sudden and severe turbulence about 3 hours prior to landing. First aid was provided on board and medical assistance was arranged at Dubai airport.

Passengers reported fellow passengers were thrown against the cabin ceiling, seat belt signs were illuminated after the first jolt. Service carts and all sort of loose items were distributed all across the aisles and aircraft following the jolts. A number of passengers were bleeding, bruises and a whiplash were treated on board.

On Jul 26th 2019 the UAE GCAA reported the occurrence was rated an accident and is being investigated. One passenger received a serious injury (neck fracture), 8 other passengers minor and 8 cabin crew also minor injuries as result of severe turbulence at FL400 near Chennai. The crew reported there had been a line of thunderstorms in the area, the aircraft continued to follow its planned route because according to weather radar the thunderstorms were off and below their path. 5 minutes prior to the turbulence encounter the fasten seat belt signs had been illuminated, the turbulence encounter happened downwind of the thunderstorm cells. A number of cabin ceiling panels were damaged as result of the encounter.

On Jul 27th 2019 The Aviation Herald received information that a storm cell was present about 140nm east of Chennai, the tops of which raised to FL480 to FL500, the aircraft crossed through that cell between 21:50Z and 22:05Z.

On Aug 26th 2020 the UAE GCAA released their final report concluding the probable causes of the accident were:

The Air Accident Investigation Sector determines that the cause of the Accident was the severe turbulence acceleration forces in clear air imposed on the Aircraft as it flew in an area affected by convective activity resulting in several unsecured passengers and cabin crewmembers forcefully impacting cabin furnishings.

Contributing Factors

The Investigation determines that the following were contributory factors to the Accident:

- The flight was planned north of an area with forecasted convective activity containing embedded cumulonimbus clouds.

- The flight crew did not request updated weather information from air traffic control or pilot reports as the Aircraft approached the area affected by the convective activity over the Bay of Bengal.

- The wet turbulence area/s displayed in magenta on the navigation display did not prompt the flight crew to use the WXR best capabilities by using WXR manual mode, enabling a more accurate assessment of the distance margin with the area of greatest threat.

- After turning the seat belt sign ON, the flight crew did not communicate with the Cabin Manager to secure the passenger cabins before the onset of the turbulence.

- The Cabin Manager and other on duty cabin crewmembers were not aware that the fasten seat belt sign had been switched ON in spite of the fasten seat belt sign flashing for five seconds and fasten seat belt chime sounding.

The GCAA reported the aircraft was flown by a captain and a first officer augmented by another captain and first officer. About one hour prior to the turbulence encounter the augmenting crew took over, during the hand over the main crew advised there was weather activity ahead with other aircraft deviating around weather.

The GCAA reported (augmenting crew flying the aircraft):

For this sector of the cruise, the Copilot was the pilot flying occupying the right pilot’s seat.

During the flight, the weather radar ‘WXR’ and ‘TURB’ functions were in AUTO mode and the ‘WX’ push button was selected on the electronic flight instrument system control panel (EFIS CP) which enabled the display of weather information on the navigation display (ND).

At 2148, as a precaution, with the Aircraft about 40 NM away from the location of the turbulence encounter, the Captain decided to turn ON the seat belt sign. There was no call from the Captain to the Cabin Manager that the seat belt sign was turned ON. No passenger announcement was made for passengers to return to their seats and fasten seat belts.

At this time, the Aircraft gross weight was 382 tons with the Aircraft in clean configuration4 at the selected cruise flight level (FL) FL400. The selected speed was 0.84 Mach with pitch angle of positive 2 degrees and a heading of 302 degrees. Autopilot 2 and both flight directors were engaged and the autothrust was active in MACH mode with the four thrust levers in maximum climb thrust (MCL) detent. The thrust levers remained in this position throughout the turbulence encounter. The wind information from the flight data recorder (FDR) indicated that the average wind was 65 kt coming from 080 degrees with a tailwind component of 55 kt together with a crosswind component from the right of approximately 40 kt.

At 2153:25 UTC (Indian local time 0323), approximately 13 hours into the flight, the Aircraft encountered different levels of turbulence that lasted until 2157:30. Severe turbulence was encountered within the first 20 seconds. This occurred close to waypoint IDASO (approximately 200 NM east of Chennai), over the Bay of Bengal, whilst in the cruise at FL400. The FDR data indicated that the Aircraft entered an area with significant wind variations.

During the interview with the crew, the Captain stated that on the ND “about 80 miles [NM] away, there was a couple of red spots [displayed on the ND] but they were well left and right of the track. The red spots disappeared as the aircraft got closer”. The flight crew stated that they adjusted the weather radar range on the EFIS CP between 160 NM for the Captain and 80 NM for the Copilot. The weather radar gain control, located on the SURV panel, was set at 85 percent for the Captain and 50 percent for the Copilot. The Captain stated that the Airbus A380 aircraft weather radar can determine what weather is relevant and what is not, which is referred to as onpath and off-path. He further explained that a decision to deviate is normally taken before the aircraft gets within 40 NM of the weather.

The flight crew stated that they had dimmed the cockpit lights to observe the lightning activity in the area, which occurred approximately every minute to 30 seconds. Because it was night time, during the lightning, they were able to see the tops of the weather and the weather below the Aircraft. However, as the tracking of the Aircraft was through a clear area with few clouds, they decided to continue with the planned flight route because the weather radar display on the ND was showing the weather as off-path.

The Captain stated that he also selected manual gain of the weather radar to have a better awareness of the weather and he reduced the range on the ND to 40 NM. The flight crew discussed flying through the squall line which they said was about 80 miles long and directly across the Aircraft’s flight path.

The flight crew reported that there was no precipitation showing on the ND and the turbulence occurred unexpectedly. They stated that there was a “thunderstorm squall line in the area, but no avoidance was required as the weather was below the aircraft and off-path. Turbulence was encountered downwind of the CBs [cumulonimbus clouds].” They believed that it was clear air turbulence.

The flight crew described that the turbulence happened very quickly and they were “jostled up and down”, and even with their seat belts on for the first minute they had to “brace themselves”. Because the airspeed had suddenly started to increase towards the maximum operating Mach (MMO) speed limit of 0.89, the Copilot tried to maintain the airspeed by immediately moving the speedbrake lever to deploy the wing spoilers and reducing the Mach target number from 0.84 to 0.72 Mach. The flight crew said that they did not observe any speed exceedance. During the turbulence, the autopilot remained engaged and there was no excessive altitude loss.

After the turbulence ended at 2157:30, the flight crew discussed the event and initially thought that the turbulence was moderate. However, within a short time, they decided it was ‘severe’ after calls started to come from the cabin crew that passengers and cabin crew were injured and that there was damage in the cabin. The Commander of the flight, who was in the crew rest compartment, called the operating Captain and they exchanged information about the occurrence. The Commander and the copilot then proceeded to the cockpit.

At the time of the turbulence, there were 15 cabin crew on duty including the Cabin Manager. Of these cabin crew, three were in first class, four in business class, seven in economy class and one seated in the cockpit. Nine cabin crew were on their scheduled rest in the crew rest compartment, located in the aft cabin, with their waist seat belts fastened. All cabin crew had followed their planned rest cycle of four hours.

For the cabin crew on duty, except for the cabin crewmember in the cockpit, and one other cabin crewmember, the remaining thirteen were standing and performing their normal duties in the cabin.

The Cabin Manager, who was in the first class cabin together with two cabin crew, described “the Aircraft shaking significantly”. As they tried to reach their jumpseats they felt like the “Aircraft dropped”. They saw many items of galley equipment used for passenger service fall to the galley floor.

The Cabin Manager then made a passenger announcement (PA) for the cabin crew and passengers to take their seats after he seated himself on the jump seat. The Cabin Manager then communicated with the Captain via the intercom system to let him know that all cabin crew were seated but there was a possibility of crew injuries.

The four cabin crew assigned to business class reported to the Cabin Manager that they were in the aft galley at the time of the turbulence and had suffered injuries when they “flew up” and impacted the ceiling.

After assessment by the Cabin Manager, it was determined that a total of 27 persons onboard comprising thirteen cabin crew and fourteen passengers, had sustained injuries. One economy passenger injury was assessed as serious after hospitalization.

Several cabin ceiling panels in the main deck aft cabin were damaged by the impact of occupants. Several items of loose galley equipment fell to the floor including beverages and food.

The flight crew established contact with the Operator’s ground medical team to assess the condition of those who had suffered injuries.

The decision was made by the Commander to continue to OMDB as none of the injuries was considered life threatening and the Aircraft systems were not affected by the turbulence encounter.

The remainder of the flight and the landing at OMDB were uneventful.

The GCAA analysed:

For the flight from Auckland to Dubai, the OFP provided to the flight crew contained the significant enroute weather charts which were effective from 1800 on 10 July 2019. The planned flight route took the Aircraft over the Bay of Bengal just north of a large area with forecasted cumulonimbus clouds.

Because it was monsoon season, convective clouds such as embedded CBs and
squalls are normally expected over the Bay of Bengal at this time of year. However, because the Commander for the flight did not consider the weather enroute to be a threat to the planned flight based on the pre-departure weather package, there were no changes made to the flight plan.

The augmenting flight crew, who operated the Aircraft during the turbulence encounter, were aware of an area of significant weather activity based on the following; the OFP significant weather chart, the handover from the outgoing flight crew with information that other flights were requesting deviations; the evidence of lightning approximately every 30 seconds; the visibility of the cloud tops; and the squall lines that they had reported. After discussion between the operating Captain and Copilot, their decision was to continue along the planned route and not request a deviation, as the weather activity was painting off-path on the navigation display (ND).

According to the significant weather chart (provided to the Investigation and not available to the flight crew) effective at 00:00 on 11 July 2019, two hours after the turbulence encounter, the forecast showed that the large area of adverse weather was still active with isolated embedded cumulonimbus clouds and was moving north-east at 15 kt with cloud tops at 46,000 ft.

The flight planning for long-range flights will always be challenging. Significant weather forecasts may change after an aircraft departs. For UAE449, the reliability of the weather forecast would have decreased over the duration of the flight time, especially as the forecast available to the flight crew was produced approximately 16 hours before the Aircraft neared waypoint IDASO.

Thus, in planning a long-range flight that has adverse weather forecast some 13 hours into the flight, there should be consideration in minimizing the risk of exposure to adverse weather conditions.

...

Being aware of the threat as the Aircraft approached waypoint IDASO, the operating flight crew became more attentive to the weather and made the necessary range adjustments to the weather radar by selecting long and short ranges. In order to have a better view of the lightning that was present during the night flight, the cockpit lights were also dimmed.

Because the Operator does not facilitate updated enroute weather information on the flight crew electronic flight bag, flight crews are instructed to contact air traffic control for the latest significant weather and pilot reports, as well as the Operator’s flight dispatch for weather updates.

As the operating flight crew assessed that they would safely pass the unsettled weather, they continued the flight along the planned route without requesting updated weather information.

Therefore, apart from the flight plan’s significant weather charts, the only other reference for the existing weather ahead was the echo returns from the weather radar system. The decision to not request additional weather information was influenced by the weather radar system which was showing that the weather as off-path, indicating that the weather system threat was below the Aircraft by at least 5,000 ft.

...

When the turbulence started at 2153, the flight crew correctly executed the FCOM Abnormal and Emergency Procedures for Overspeed Prevention and kept the autopilot and autothrust engaged. The Copilot deployed the speed brakes and reduced the selected speed, however unknown to the flight crew, the maximum operating Mach number (MMO) was momentarily exceeded. The Aircraft post flight report confirmed that there was an OVERSPEED warning triggered which the flight crew was not aware of.

The severity of the turbulence encounter was not immediately known to the flight crew but was quickly classified as severe when the cabin crew reports of injuries and cabin damage were received. When the cabin crew reported the need to contact the Operator’s medical ground support, the flight crew became busy, so no notification was sent to air traffic control advising that the Aircraft had experienced severe turbulence.

...

For the different flight phases, including cruise at FL400, the Aircraft was flown in the correct configuration and attitude with the autopilot and autothrust engaged.

Five minutes before the start of the turbulence encounter at 2153:25, the Aircraft had a tailwind component of approximately 55 kt and a right crosswind component of 40 kt. The airspeed was maintained at the target of 0.84 Mach.

At the beginning of the turbulence encounter, the FDR data indicated significant wind variations. The tailwind component reduced suddenly to about 17 kt. and in the lateral axis there where short bursts of left and right crosswind component gusts varying between 29 kt. and 40 kt.

Severe turbulence occurred within the initial 20 seconds, from 2153:25 until 2153:45. This caused variations in the Aircraft attitude, altitude and a sudden airspeed increase, which momentarily exceeded MMO. The Aircraft systems responded in order to avoid the overspeed, however even with the autothrust reducing the engine thrust and the automatic deployment of the speedbrakes, there was an exceedance of the MMO speed that resulted in an overspeed warning lasting three seconds.

During the turbulence, as designed, the load alleviation function (LAF) had automatically engaged for about 27 seconds in order to reduce the fatigue and static loads on the wings. During this time, there were 10 symmetrical deflections of the ailerons and/or the outer spoilers upwards.

Based on the Airbus analysis, the turbulence encounter resulted in the Aircraft and occupants experiencing significant variations of vertical and lateral load factor and angle of attack, which were consistent with the adverse wind variations.

The Investigation concludes that throughout the severe turbulence encounter, the Aircraft autopilot and autothrust remained engaged, and the Aircraft remained controllable. The Aircraft systems, as designed, automatically responded to sudden flight variations in order to avoid the overspeed. However, due to the sharp longitudinal wind variation, the thrust adjustment and the automatic speed brakes deployment were not sufficient to avoid the transient MMO exceedance and Mach number reached MMO +0.006 leading to an overspeed warning.

...

The Investigation believes that the detection of wet turbulence requires further explanation and guidance in the FCOM and FCTM by the Aircraft Manufacturer so that there is clear understanding and actions required by pilots. Knowing the capabilities and limitations of the weather radar installed on the aircraft is essential as well as being familiar with the techniques to optimize the use of the weather radar.

...

Prior to the turbulence, there were 15 cabin crewmembers on duty serving the 378 passengers. Of these cabin crew, one was in the cockpit, seven were serving 78 first and business class passengers in the upper deck, and seven were serving the 300 economy class passengers in the main deck.

When the operating Captain turned the seat belt sign ON at about 2148, the Aircraft was almost 13 hours into the flight. At this time, passenger cabin service was minimal and no serving trolleys were in the cabins.

The flight crew’s intention of switching the seat belt sign ON, was for the passengers to return to their seats and fasten their seat belts. However, this was not verbally communicated to the Cabin Manager. The flight crew did not anticipate that the cabin service would have been affected, thus, the cabin crew continued their normal duties. Except for the cabin crewmember in the cockpit and the one seated in the upper deck forward jump seat, the remaining 13 cabin crew on duty were standing either in the galleys, cabin or near the lavatories.

None of the 15 cabin crewmembers who were on duty could recollect either seeing the seat belt sign coming ON or hearing the chime when the seat belt sign was switched ON. Because of this lack of awareness, there was no cabin readiness performed for the upper and main passenger decks as required when the seat belt sign is switched ON.

It was only during the turbulence encounter that the Cabin Manager made a passenger announcement (PA) for all cabin crew and passengers to take their seats and to fasten their seat belts. At this time, it was too late as several persons onboard had already suffered injuries.

The severity of the wind variations resulted in significant vertical g-loads between minus 0.35G and positive 1.65G. As a result, several unrestrained passengers and cabin crewmembers were lifted off their feet and impacted the cabin ceiling causing injuries and damages. The Aircraft movements were more significant in the aft cabin and aft galleys for both the upper as well as the main cabin which resulted in several galley equipment being tossed on the galley floor.

For the status of the passenger’s seat belts, it is most likely that the majority of passengers had complied with keeping their seat belts fastened for their own personal safety, as the number of injured passengers, especially in the aft cabin, would otherwise had increased.

Passengers who had their seat belts fastened, were either aware of the seat belt sign coming ON or had paid attention to the Commander’s and cabin crew passenger address before takeoff communication of keeping their seat belts fastened whilst seated.

Of the 14 passengers who were injured, two were in the lavatories and 12 were seated.

Based on the post turbulence analysis done by the Operator, as well as the cabin crew report, of the 12 injured passengers, it was confirmed that six injured passengers did not have their seat belts fastened. Due to the severity of the turbulence, it is most likely that the remaining six injured passengers did not have their seat belts fastened.

Of the 13 cabin crew who suffered minor injuries, 12 were in the aft cabin and one was in the forward cabin. Of the 12 cabin crew in the aft cabin, five were in the galleys and seven were resting in crew rest compartment with their seat belts fastened.

...

For an aircraft like the A380 with close to 500 passengers, during a long-range flight when there are less cabin crew on duty due to planned rest cycles, it may not be possible for the available cabin crew to stop cabin services, stow galley equipment, and visually verify that each passenger has seated with their seat belts fastened if there is not sufficient notice from the flight crew. Because the automated audio announcement throughout the cabin to fasten seat belt feature when the seat belt sign was turned ON was progressively discontinued from all of the Operator’s aircraft starting from 2008, ensuring timely notification and communication from the flight crew to the cabin crew becomes even more critical.

The Investigation concludes that there were missed opportunities that started five minutes before the severe turbulence encounter to have the cabin ready before the turbulence encounter. The cabin crew lacked the awareness of the seat belt sign status even though the flight crew had turned the seat belt sign ON. The possible threat of associated turbulence because of the thunderstorms that was observed by the flight crew was not communicated to the Cabin Manager. It is possible that during many flights, there will be times when the seat belt sign will be switched ON more than once for anticipated turbulence. Especially during long-range flights, it is possible that the cabin crew may become less alert thus missing the seat belt chime sounds and the flashing of the seat belt sign.

...

The sound of the low tone chime when the seat belt sign is turned ON is intended to attract the attention of the cabin crew and passengers. However, if they fail to hear this chime, then it is possible that they may not notice that the seat belt sign has been switched ON. The Investigation could not test how audible the chime is in flight, especially when the cabin crew are busy in the galleys. However, the fact that not one cabin crew member out of 15 who were carrying out their duties in the cabin did not hear the chime is notable.
Incident Facts

Date of incident
Jul 10, 2019

Classification
Accident

Flight number
EK-449

Aircraft Registration
A6-EEM

Aircraft Type
Airbus A380-800

ICAO Type Designator
A388

This article is published under license from Avherald.com. © of text by Avherald.com.
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