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What happened

On 11 May 2015, a Boeing 737 aircraft, registered VH-VOP and operated by Virgin Australia International, conducted a scheduled passenger service from Sydney, New South Wales to Christchurch, New Zealand.

Shortly after midnight, the aircraft landed on runway 29 at Christchurch. Runway 29 was shorter than the main runway at Christchurch. The aircraft landed within the required touchdown zone, using full reverse thrust, speedbrakes, and the autobrake system engaged the wheel brakes. Recorded flight data showed that the aircraft initially achieved, and at times exceeded the selected AUTOBRAKE 3 target deceleration rate. However, after crossing the runway intersection, the aircraft did not continue to decelerate as expected and the crew believed the aircraft appeared to slide or skid. In response, the crew overrode the autobrakes and applied hard manual braking while retaining full reverse thrust for longer than used in normal operations. The crew also corrected a minor directional deviation. The aircraft came to a stop about 5 m from the runway end. There were nil recorded injuries or aircraft damage.

What the ATSB found

The ATSB found that, due to increased workload, the crew misperceived the runway surface conditions and believed it was damp when in fact it was wet. As there was no regulatory direction on how a damp runway was to be considered for aircraft landing performance purposes, the operator’s policy was to treat a damp runway the same as a dry runway. As a result, the crew established the aircraft’s landing performance based on a dry rather than a wet runway and the expected runway 29 landing performance was not achieved.

The ATSB also found that, several months prior, the operator had changed its policy whereby damp runways had previously been treated as wet runways.

Based on the crew’s observations and a review of the available recorded data, it was very likely that the surface conditions on the later part of the runway had degraded to the extent that they adversely affected the aircraft’s braking capability. It was also possible that the aircraft experienced viscous aquaplaning. However, the initial exceedance of the target deceleration rate, combined with the crew’s actions, likely prevented a runway overrun.

Further, a post-incident analysis of the flight data recorder by the aircraft manufacturer found that a 5 kt tailwind existed on final approach and landing. This also significantly affected the aircraft’s landing performance and further reduced safety margins.

Additionally, and along with the United States Federal Aviation Administration, the ATSB found that the 15 per cent in-flight safety margin applied to actual landing distances during landing performance calculations may be inadequate under certain runway conditions. In these conditions, additional conservatism is encouraged.

Safety message

This incident highlights the adverse consequences of crew experiencing a high workload during critical phases of flight, including missing important information needed to determine an accurate landing performance.

In addition, runway surface condition and braking action reports (intended for the benefit of other pilots landing aircraft after them) can be subjective, and the terminology used to describe these can be inconsistent. Considerable efforts have been made by organisations such as the United States Federal Aviation Administration to address this issue with the introduction of the runway condition assessment matrix.

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The occurrence

Context

Safety analysis

Findings

Safety issues and actions

Sources and submissions

Terminology used in this report

Appendices

 

Safety issues

AO-2015-046-SI-01 - AO-2015-046-SI-02 - AO-2015-046-SI-03 - AO-2015-046-SI-05 -  

Change in ‘damp’ definition for performance purposes

Several months prior to the incident, Virgin Australia Airlines/Virgin Australia International changed their policy on calculating landing performance for damp runways from referencing a wet runway to a dry runway.

Safety issue details
Issue number:AO-2015-046-SI-01
Who it affects:Virgin Australia Airlines/Virgin Australia International crews
Status:Safety action pending


 

Regulatory direction regarding damp runways

There was no regulatory direction from the Civil Aviation Safety Authority on how a damp runway was to be considered for aircraft landing performance.

Safety issue details
Issue number:AO-2015-046-SI-02
Who it affects:Operators and pilots of aircraft where landing performance data is not available for damp runway surface conditions
Status:Safety action pending


 

Cross-checking environmental information and landing performance

Virgin Australia Airlines/Virgin Australia International did not have a policy requiring crews to independently cross-check environmental information and landing performance calculations in-flight, removing an opportunity to detect crew errors.

Safety issue details
Issue number:AO-2015-046-SI-03
Who it affects:Virgin Australia Airlines/Virgin Australia International crews
Status:Safety action pending


 

In-flight landing distance safety margin may be inadequate

Civil Aviation Order 20.7.1B stipulated that a 1.15 (15 per cent) safety margin was to be applied to the actual landing distance for jet-engine aircraft with a maximum take-off weight greater than 5,700 kg. This safety margin may be inadequate under certain runway conditions, which increases the risk of a runway excursion. The corresponding guidance in Civil Aviation Advisory Publication 235-5(0) had not been updated to account for this.

Safety issue details
Issue number:AO-2015-046-SI-05
Who it affects:Civil Aviation Safety Authority
Status:Safety action pending

 
General details
Date: 11 May 2015 Investigation status: Completed 
Time: 1214 UTC Investigation phase: Final report: Dissemination 
Location   (show map):Christchurch International Airport Investigation type: Occurrence Investigation 
State: International Occurrence type: Control issues 
Release date: 18 September 2018 Occurrence class: Operational 
Report status: Final Occurrence category: Incident 
 Highest injury level: None 
 
Aircraft details
Aircraft manufacturer: The Boeing Company 
Aircraft model: 737-8FE 
Aircraft registration: VH-VOP 
Serial number: 33797 
Operator: Virgin Australia International Airlines 
Type of operation: Air Transport High Capacity 
Sector: Jet 
Damage to aircraft: Nil 
Departure point:Sydney, NSW
Destination:Christchurch, NZ
 
 
 
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Last update 18 September 2018