Virgin Australia B738 near Bali on Sep 14th 2012, wake turbulence from A380

Last Update: April 23, 2013 / 15:10:36 GMT/Zulu time

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Incident Facts

Date of incident
Sep 14, 2012

Classification
Incident

Airline
Virgin Australia

Flight number
DJ-4198

Departure
Denpasar Bali, Indonesia

Destination
Brisbane, Australia

Aircraft Registration
VH-YIO

Aircraft Type
Boeing 737-800

ICAO Type Designator
B738

A Virgin Australia Boeing 737-800, registration VH-YIO performing flight DJ-4198 from Denpasar Bali (Indonesia) to Brisbane,QL (Australia) with 132 passengers and 6 crew, was enroute about 140nm southeast of Bali (position approximately S10.44 E116.7855) when the aircraft encountered wake turbulence from an Emirates Airlines Airbus A380-800, registration A6-EDO performing flight EK-413 from Sydney,NS (Australia) to Dubai (United Arab Emirates), flying in opposite direction. Both aircraft reached their destinations safely.

Australia's TSB reported initially the 737 had encountered the wake turbulence over Northern Territory of Australia at Sep 14th 08:12 CST (UTC+9.5, 22:42Z Sep 13th), The Aviation Herald attempted to identify the A380 with these data and was unable to identify any matching flight and sent an according inquiry to the ATSB which was left without reply.

The French BEA reported in their weekly bulletin on Sep 25th the wake turbulence occurred in Indonesian Airspace.

Following the inquiry by The Aviation Herald, although no reply was sent, the ATSB brief was updated to identify the wake turbulence happening 258km southeast of Bali Denpasar at 16:42Z, about half an hour after departure from Bali. The ATSB left the A380 unidentified, but have opened an investigation into the serious incident.

Radar data rule out any Qantas and Singapore Airlines A380 flight, however, the Emirates EK-413 flight overflew the turbulence location S10.44 E116.7855 at approximately 16:42Z.

On Apr 23rd 2013 the ATSB released their short investigation bulletin releasing following safety messages to flight crew and passengers:

Recurrent training

Periodic recurrent training ensures that pilots continue to be knowledgeable of, and proficient in their specific aircraft type, and operating procedures: pilots are better prepared for responding to a situation. This incident demonstrated the value of such training, allowing the crew to react to the wake turbulence encounter intuitively and promptly.

Seat belts

A wake turbulence encounter can be a surprising experience for both the crew and passengers and usually results in induced rolling or pitch moments. A safety bulletin published by the ATSB in June 2008, Staying Safe against In-flight Turbulence, noted that almost all turbulence injuries involve people who are not properly seated and do not have their seat belt fastened. This incident is a timely reminder of the benefits of having the seat belt fastened, even when the seat belt sign is turned off, so that injuries during a turbulence encounter can be minimised.

The ATSB reported that the crew of VH-YIO had requested FL370 after departure from Denpasar, however, due to traffic at FL360 had been cleared to climb to FL350. Flight conditions at FL350 were smooth, the crew reported calm winds. The fasten seat belt signs were extinguished. About a minute later the crew observed traffic in opposite direction, according to the TCAS display the traffic was 1000 feet above and slightly to the left of their track, Air Services Austrialia radar data showed the A380 about 0.9nm left and 1400 feet above the Boeing 737.

A minute after the aircraft had passed each other the Boeing 737 encountered wake turbulence throwing the aircraft slightly to the right and then to about 45 degrees of bank to the left, a bank angle aural warning was issued, the autopilot reverted to steering wheel mode. The crew applied full right aileron, the aircraft however continued to roll left initially though at reduced roll rate before wings started to level, the duration of the encounter was about 10 seconds. Air Services Australia Radar data suggest that at that time the aircraft were separated 1400 feet vertically and 2.1nm horizontally, the flight data recorder revealed a maximum left bank angle of 40.4 degrees, the aircraft lost 40 feet of altitude during the turbulence encounter.

The ATSB quoted the Boeing crew stating, that they did not hear the term Super, used to identify the wake turbulence category, on any transmission they heard. Had they known an A380 was about to overfly them, they would have requested an offset off the airway center line. In a similiar situation, the crew of another flight had heard the term "Super" and had requested and was cleared for a 5nm offset from the airway, permitting the aircraft to pass the A380 without any encounter.

The ATSB stated: "An Airbus Flight Operations Briefing Note on Wake Turbulence Awareness/Avoidance also recommends that, during the cruise (if necessary), the crew may offset from the cleared track by up to a maximum of 2 NM, in order to alleviate the effects of wake turbulence."

The captain subsequently talked to cabin crew, who informed there had been no injuries. The captain subsequently inquired with ATC and was told an Emirates Airbus A380-800 (the entire report does not identify more of the A380) had just passed them, the captain subsequently made a public announcement to the passengers.