Safety in aviation is paramount and is represented by the high amount of regulation, training and maintenance standards within the industry. The Civil Aviation Authority of New Zealand is responsible for maintaining these high standards of professionalism and is a key driver behind it leading the New Southern Sky Programme. 

What are the safety benefits?

The global aviation system is already very safe, so improving on this track record through introduction of new technologies has the potential to introduce new risk into the system if it is not managed appropriately. In saying this, there is considerable benefit to be drawn from the improvements technology brings. It is difficult to argue against the fact that aviation is now at the highest levels of safety since the advent of manned flight. One such benefit is the safety performance based navigation (PBN) brings to aviation. PBN can increase safety by reducing risk factors associated with a flight’s approach to landing, and resolutions by the 36th and 37th assemblies of ICAO requiring member states to implement PBN were in part to realise this potential safety improvement.

What are the safety impacts?

The reduction in risk can be substantial. Several safety studies in the 1990s analysed the root causes of controlled flight into terrain (CFIT) accidents in the approach and landing phases of flight. This class of accident occurs when the aircraft remains under control, but pilots have lost situational awareness through becoming distracted or disoriented or otherwise, in situations where insufficient safeguards exist to ensure their continued ability to navigate the aircraft correctly. Based on a large number of accident histories, the research found that runway aligned landing approaches with lateral guidance were 25 times safer than approaches made by circling the airport to align the aircraft with the runway visually. Approaches are 8 times safer again when the approach includes vertical guidance. 

PBN approaches reduce these risks. Approaches with lateral guidance that are aligned with the runway at the end of the approach avoid the need to manually maneuver the aircraft close to the runway or ground, and can be flown automatically by suitably equipped aircraft. Approaches with vertical guidance (APV) are flown with a continuous descent that is either indicated or automatically flown by aircraft systems. The risks on the approach to landing are reduced by flying a more stable flight profile, increased use of automation and reducing the pilot workload, providing pilots with more resources to handle events that may arise.

The short video (produced by Adrian Schofield, Air transport Editor, Asia-Pacific for Aviation Week) below illustrates the safety improvements through the use of PBN landing in Queenstown, particularly with regard to flying night operations. It also introduces the concepts of virtual highways in the sky, or Digital Infrastructure.


The instrument approaches being implemented in the NSS Programme deliver these safety improvements. The NSS concept of operations calls for all instrument approaches to runways at controlled aerodromes to use PBN procedures with APV. Prior to PBN, APV was available only at airports with instrument landing systems (ILS). When the current phase of the NSS Programme is complete, APV will be available at nearly all attended and some unattended aerodromes served by scheduled passenger traffic.

What's difference does it make in New Zealand?

Recent analysis does not place a financial value on the safety improvement, but identifies the airports to be addressed in the current phase of the PBN project, and the approximate number of passengers annually carried by flights making instrument approaches to those airports. The benefits identified are summarised in the table below.

How can these safety benefits be valued?

Safety values are often difficult to establish, typically as they relate to infrequent events. While reasonably well established material exists for road transport safety improvements and more generally for industrial accidents, the infrequency of commercial aircraft accidents makes it very difficult to establish any reasonable basis for probabilities or even scale of loss.

While there generally is no clear and separate price paid for safety in this context, various techniques for establishing some proxies for the value of changes in the level of safety exist. For example one study[1] found, using a contingent valuation survey, that people’s willingness to pay for a given risk reduction is found to be much larger, consistently more than two times as large, when travelling by air compared to by taxi. Follow-up questions revealed that an important reason for this discrepancy is that many experience a higher mental suffering from flying, and that they are willing to pay to reduce this suffering. It was also consistently found that people are willing to pay more for a certain risk reduction if the original price was higher.

Although it was beyond the scope of the 2017 cost benefit analysis report to identify a value for air safety, some potential value scenarios can be considered: air passengers flying domestically pay $5.05 per departure as an aviation security fee (albeit involuntarily and perhaps unknowing). Even if the benefits from PBN were only 20% of those benefits, a safety value of $1 per passenger could be considered. 

[1] FREDRIK CARLSSON et al “Is Transport Safety More Valuable in the Air?” The Journal of Risk and Uncertainty, 28:2; 147–163, 2004