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SF34, vicinity Sydney Australia, 2008

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Summary
On 3 November 2008, a Saab 340B being operated on a domestic passenger flight by Regional Express AL was tracking in daylight to join a 7nm final for Runway 34R at destination Sydney, when a passenger sustained minor injuries as the result of a transient encounter with turbulence that had led to a momentary loss of control of the aircraft and which was suspected as being of wake vortex origin.
Event Details
When November 2008
Actual or Potential
Event Type
Loss of Control, Wake Vortex Turbulence
Day/Night Day
Flight Conditions VMC
Flight Details
Aircraft SAAB 340
Operator Regional Express Airlines
Domicile Australia
Type of Flight Public Transport (Passenger)
Origin Orange Airport
Intended Destination Sydney Airport
Take off Commenced Yes
Flight Airborne Yes
Flight Completed Yes
Flight Phase Descent
ENR / APR
Location - Airport
Airport vicinity Sydney Airport
LOC
Tag(s) Uncommanded AP disconnect,
Temporary Control Loss,
Extreme Bank
WAKE
Tag(s) ICAO Standard Wake Separation prevailed
Outcome
Damage or injury Yes
Injuries Few occupants
Causal Factor Group(s)
Group(s) Aircraft Operation
Safety Recommendation(s)
Group(s) None Made
Investigation Type
Type Independent

Description

On 3 November 2008, a Saab 340B being operated on a domestic passenger flight by Regional Express AL was tracking in daylight to join a 7nm final for Runway 34R at destination Sydney, when a passenger sustained minor injuries as the result of a transient encounter with turbulence that had led to a momentary loss of control of the aircraft and which was suspected as being of wake vortex origin.

The Investigation

An Investigation was carried out by the Australian Transport Safety Board who found by examination of the available radar, meteorological and aircraft operational data that the momentary upset probably resulted from wake turbulence generated by an Airbus A380 that was conducting a parallel approach to Runway 34L. It was noted that there was a 35 knot crosswind from the left affecting the approaches of both aircraft.

The encounter was found to have occurred at an altitude of about 2,400 feet amsl and involved an uncommanded 52º roll to the left (which led to an uncommanded autopilot disconnect) and a simultaneous 8º nose-down pitching motion. Immediately after, the aircraft rolled through wings level to a 21° right bank angle. The encounter led to an altitude loss of 300 to 400 ft in the 9 to 15-second period during control was regained. At the time of the event it was estimated that the aircraft was about 260 metres to the right of the Runway 34R centerline.

Subsequent to the event, the ANSP advised the aircraft operator that, as a result of this incident, they had introduced a number of interim minor changes to Sydney parallel runway operational procedures during high crosswind conditions pending a full review of A380 operations. In addition, the National Aviation Authority (NAA) has also begun a review of wake turbulence separation information.

The Investigation concluded that there were three contributing Safety Factors in respect of the Incident:

  • There was no requirement for wake turbulence separation to be provided by Air Traffic Control in respect of aircraft operations on the adjacent parallel runway.
  • The strong crosswind caused the wake turbulence that was generated by the A380 operating on Runway 34L to drift across to the final approach path for Runway 34R.
  • Due to the location of the respective runway thresholds, the approach path for Runway 34L was higher than the approach path for Runway 34R at a fixed distance from the airport, resulting in the drifted A380 wake turbulence descending onto the S340’s final approach path.


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