Recommendation R20060019

Recommendation issued to: Civil Aviation Safety Authority

Recommendation details
Output No: R20060019
Date issued: 16 December 2006
Safety action status: Closed - No Action
Background: Why this Recommendation was developed

Output text

Safety issue: RNAV (GNSS) approach pilot workload and situational awareness

Pilot workload was perceived as being higher, and reported losses of situational awareness were reported as more common, for the area navigation global navigation satellite system (RNAV (GNSS)) approach than all other approaches except the non-directional beacon (NDB) approach, which involved similar workload and situational awareness levels.

This was especially a concern for pilots operating Category A and Category B aircraft. Further research into pilot workload and losses of situational awareness associated with RNAV (GNSS) approaches is warranted.

Safety Recommendation

The Australian Transport Safety Bureau recommends that the Civil Aviation Safety Authority address this safety issue.

Initial response
Date issued: 06 March 2007
Response from: CASA
Action status: Monitor
Response text:

In respect of recommendation R20060019, CASA will have the findings of the report considered by the Australian Strategic Air Traffic Management Group (ASTRA), consult with regulators overseas and review research findings from other studies (particularly a recent one by Leeds University in the UK). It would be helpful, however if the ATSB would provide further clarification on the additional research that it recommends be undertaken into pilot workload (especially given the low response rate and limited available data cited in the present study).

ATSB response:

In response to this recommendation CASA noted that there was limited available data cited in the ATSB report concerning pilot workload.  The ATSB study was based on subjective estimates of workload and other factors by pilots and the results suggest that follow-up research with objective measures of workload is warranted. As we point out in our report, there have been very few other studies conducted on this matter, and the few that have been published tend to restrict their focus to high capacity RPT operations, where workload issues may be substantially different from those faced by pilots in other operational categories and/or single pilot operations (typically Category A and Category B aircraft).  ATSB therefore holds the view that additional research on this topic is warranted to extend the knowledge gained from our own research, and particularly to better understand the differences in workload and time pressures faced by pilots of Category A and Category B aircraft compared with other instrument approaches and pilots of high capacity, multi-crew airline operations.

The ATSB acknowledges that CASA has developed important and useful educational material to assist pilots with the transition to RNAV (GNSS) approaches, and that this information was recently updated and reissued.  The ATSB also notes that CASA touched on this issue in an article in a recent edition of Flight Safety Australia

Further correspondence
Date issued: 26 March 2007
Response from: CASA
Response status: Monitor
Response text:

In regard to R20060019, CASA will continue to monitor developments in this area, particularly in the United Kingdom. To this end, CASA will be meeting staff of the UK CAA shortly to discuss recent work done by them on RNAV (GNSS) approaches. The issues raised in your report have also been raised at the recent ICAO Navigation Systems Panel. At the present time, however, it is unlikely that CASA will be in a position to commission specific research, either from universities or in-house. 

Further correspondence
Date issued: 17 February 2009
Response from: Safety action rolled into AI-2007-2010 Safety Issue investigation
Response text:

This safety action was closed without a redesign of the Lockhart River runway 12 approach. A Safety Issue investigation (AI-2007-010) into the design of the Lockhart River runway 12 RNAV (GNSS) approach with respect to activation of Mode 2A ground proximity warning system (GPWS) is continuing. This Safety Issue investigation has established that RNAV (GNSS) approaches can now be redesigned using the revised obstacle clearance areas released by ICAO on 31 October 2008. The revised obstacle clearance areas should enable some RNAV (GNSS) approaches to be re-designed with simpler intermediate segment lengths and profile gradients. It may also allow for the moving the Lockhart River Runway 12 RNAV (GNSS) approach away from 'South Pap' which may remove the current requirement for uneven intermediate segment lengths and/or steeper than normal profile.

Further correspondence
Date issued: 18 September 2009
Response from: Airservices Australia
Response status: Closed - Accepted
Response text:

On 18 September 2009, Airservices Australia advised the ATSB that the Lockhart River runway 12 RNAV (GNSS) non-precision approach had been redesigned using the revised ICAO PANS-OPS DOC 8168 design criteria for RNAV (GNSS) approaches. The procedure has been flight validated. The new approach is more direct and allows for a straight approach to the Lockhart River runway, rather than the existing five degree off set. The minima, or lowest point for descent on the approach, has been reduced by around 60 feet and the approach now largely follows the valley into Lockhart River. However, due to terrain considerations, the PANS-OPS terrain clearance criteria did not allow the standard 5-5-5 NM segments to be included. The new approach will be published in the Aeronautical Information Publication amendment effective 19 November 2009.

ATSB comment:

The ATSB accepts that Airservices Australia has now met the intention of the safety recommendation. Although it is probable that the pilot workload associated with this approach is still higher than for standard 5-5-5 NM segments, as the approach now follows the valley and the approach chart displays coloured terrain contour lines, the risks have been reduced as low as reasonably practicable given the confines of the terrain and PANS-OPS design criteria. The ATSB has closed this safety recommendation - action taken.

Last update 05 April 2012