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A388, en-route, Wyoming USA, 2020

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Summary
On 2 February, an Airbus A380 in the cruise at night at FL 330 encountered unforecast clear air turbulence with the seatbelt signs off and one unsecured passenger in a standard toilet compartment sustained a serious injury as a result. The Investigation noted that relevant airline policies and crew training had been in place but also observed a marked difference in the availability of handholds in toilet compartments provided for passengers with disabilities or other special needs and those in all other such compartments and made a corresponding safety recommendation to standardise and placard handhold provision in all toilet compartments.
Event Details
When February 2020
Actual or Potential
Event Type
Loss of Control, Weather
Day/Night Night
Flight Conditions VMC
Flight Details
Aircraft AIRBUS A-380-800
Operator Emirates
Domicile United Arab Emirates
Type of Flight Public Transport (Passenger)
Origin Los Angeles
Intended Destination Dubai International Airport
Take off Commenced Yes
Flight Airborne Yes
Flight Completed Yes
Flight Phase Climb
ICL / ENR
Location En-Route
Origin Los Angeles
Destination Dubai International Airport
Location
Approx. Airspace over Wyoming, Salt Lake City FIR
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General
Tag(s) CVR overwritten
LOC
Tag(s) Environmental Factors
WX
Tag(s) CAT encounter
CS
Tag(s) Pax Turbulence Injury - Seat Belt Signs off
Outcome
Damage or injury Yes
Injuries Few occupants
Causal Factor Group(s)
Group(s) Aircraft Operation
Safety Recommendation(s)
Group(s) Aircraft Operation
Investigation Type
Type Independent

Description

On 2 February, an Airbus A380-800 (A6-EON) being operated by Emirates on a scheduled international passenger flight from Los Angeles to Dubai as EK216 with an augmented crew was in the cruise over the Rocky Mountains in night VMC at FL 330 when it suddenly encountered a brief period of unforecast significant turbulence which resulted in a serious injury to one of the 333 passengers. After a medically-informed assessment of the injury, the flight was completed to destination where the seriously injured passenger was hospitalised.

Investigation

The UAE GCAA Air Accident Investigation Sector (AAIS) was notified of the event by the operator and notified to the NTSB as the investigation agency for the State of Occurrence. Four days after the event, the NTSB then delegated the conduct of the Accident Investigation to the AAIS. Relevant data was downloaded from the FDR but as the flight had continued for more than two hours following the turbulence, relevant data from the CVR had been overwritten so was not accessed.

What happened

After the flight departed Los Angeles just after midnight with the Captain as PF, the flight planned route for the first two hours, which was followed, eventually took it over the northern Rocky Mountains in the State of Wyoming. Since the operational flight plan provided to the crew indicated that no significant weather was expected to affect the flight on this route, the Captain had switched off the seat belt signs once the flight was above FL 100.

As the flight transited the Salt Lake City FIR and passed near the 12,244 feet high Trout Peak, part of several ridges which make up the Absaroka range, a two minute long period of turbulence suddenly began at FL 330 during a climb to FL350 before ceasing as quickly as it had begun. During this period, the actual speed (with M0.85 selected) was recorded as varying between M0.812 and M0.876, vertical speed as varying between -580 fpm and +1,400 fpm, vertical acceleration as varying between +0.44g and 1.63g and the pitch attitude as ranging from +0.7° and +3.5°.

Three seconds after the start of the turbulence, the flight crew switched on the seat belt signs and made a PA instructing the cabin crew to seat and secure themselves. The AP 1 and both FDs remained engaged and the A/THR (autothrottle/autothrust) was in ‘Thrust Climb’ mode. It was noted that four seconds after the start of the turbulence, the flight crew changed the FMS longitudinal mode from CLB mode to V/S mode.

The sensed wind velocity recorded on the FDR during the turbulence indicated a mean wind from 080° at 65 knots and that with the aircraft on a heading of 020°, the actual tailwind component had varied between 11 and 43 knots and the actual crosswind component had varied between 20 and 82 knots from the right. The sensed vertical air movement during the same period varied between a downdraft of 14 knots and an updraft of 31 knots although it was noted that there had been “no excessive altitude loss”.

The approximate location of the turbulence encounter. [Reproduced from the Official Report]
Part of the forecast significant weather chart for the flight with the location of the turbulence. [Reproduced from the Official Report]

In the complete absence of any evidence of wet turbulence on the correctly set up weather radar, and no evidence that there had been any cloud in the airspace where the event occurred, the Investigation was able to conclude that the encounter, as believed by the flight crew, had been attributable to CAT.

The flight crew reported that when they had earlier been approximately 55 nm south west of the turbulence encounter position, aircraft at a lower altitude - below FL 290 - on the same frequency had been heard reporting “light turbulence” to ATC when they were in the same area but noted that ATC “had not communicated to us any ‘ride reports’ or turbulence at our level or at FL350.” The First Officer also noted that after hearing these communications from other aircraft, he had been prompted to check shear rates shown on the Operational Flight Plan which for the final stage of the climb to the initial cruise level had been shown as either ‘0’or ‘1’. The crew also reported that there were no other aircraft ahead at the same level or in the opposite direction within ±1,000 feet.

The provision of toilets on the aircraft

The passenger injury which had led to the Investigation had occurred in a toilet compartment and was reported to have been caused after the standing passenger had been “forced up in the air” before landing heavily. This resulted in the provision of toilet compartment handholds being examined. It was found that although such compartments as were designated for use by passengers with disabilities or other special needs were equipped with multiple handholds at different heights which were easily reachable in all circumstances, other toilets had only one or two handholds. It was found that the orientation of handholds in compartments with only one handhold was either horizontal or vertical and in those with two, one was oriented horizontally and one vertically. However, although these handholds were placed on the compartment wall within reachable distance and height for a person who was seated on the toilet, none had handholds adjacent to the basin and in some cases, if the occupant was using the basin, the installed handhold would be behind their back and thereby not within easy reach. It was also noted that there were no placards in the toilet compartments to alert the passengers to make use of the available handholds in the event of turbulence.

It was nevertheless accepted that it was not possible to be certain that identified deficiencies in relation to toilet compartment handholds had contributed to this accident as it was not possible to interview the injured passenger. However, the fact that a similarly-caused passenger injury had occurred in another recently investigated A380 turbulence encounter also investigated by the GCAA AAIS was noted.

The Cause of the accident was formally documented as “the acceleration forces imposed on the aircraft as it flew through an area of clear air turbulence, which resulted in an unsecured passenger forcefully impacting cabin furnishings in the lavatory”.

A Contributory Factor was also identified as “the lack of placarded instructions and the inaccessibility of the handholds within the lavatory for use in case of turbulence”.

One Safety Recommendation was made as a result of the Investigation as follows:

  • that Emirates standardize and improve the accessibility of the lavatory handholds and include placarded instructions on the use of the handholds in case of turbulence. [SR81/2020]

The Final Report was issued on 10 September 2020.

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