What does P-RNAV offer?

Compared to the current situation, the most important aspect that P-RNAV offers is the consistency in RNAV procedure design and execution. This in itself provides a safety benefit, and is main driver for the introduction of P-RNAV procedures in ECAC Terminal Airspace. Considering P-RNAV as the appropriate requirement for Terminal Airspace RNAV operations, it becomes the enabler for RNAV operations in Terminal Airspace providing all the associated RNAV benefits.

P-RNAV offers the ability to use RNAV functionality in all phases of flight except final approach and missed approach. This allows the routes in the terminal airspace to be defined to best meet the needs of the airport, the air traffic controller and the pilot. This often means shorter, more direct routes with simple connections to the en-route structure. However, where environmental issues play a major role, the route can be designed to make best advantage of the airspace available and, where possible, by-pass densely populated areas. Careful design can also result in appropriately segregated arrival and departure streams, thereby reducing the need for radar vectors and hence the workload for both the pilot and the controller. Fewer radar vectors also means less uncertainty on the flight deck with regard to the anticipated tactical route and the distance to go.

The P-RNAV certification and operational approval criteria were developed with the intent of causing the least disruption and cost to the existing aircraft fleet. Many of the systems in use today are capable of trackkeeping accuracies far better than ± 1NM and the requirements were developed with the intent of satisfying the majority of the existing RNAV systems in order that full benefit can be derived from their features.

More on P-RNAV benefits

As explained above, existing RNAV application in ECAC Terminal Airspace is characterised by national and/or local variations to address specific requirements. Whilst these varying applications have been approved by national authorities (usually for national use), the variety of national operational approval requirements and national ATC procedures has certain safety implications from an ECAC-wide perspective.

As such, the ECAC-wide consistency brought about by common P-RNAV application will enhance the safety of RNAV operations in Terminal Airspace by addressing, in particular,

• Common Airworthiness and Operational approval;
• Common ATC procedures.

Given the ECAC-wide consistency offered by common P-RNAV application, the absence of 'national' RNAV applications means that RNAV terminal area procedures will be available for use for all operators and not only 'national' operators.

Above and beyond the ECAC-wide safety advantages that P-RNAV provides, the enhanced accuracy capability of P-RNAV approved aircraft means that less airspace is required to accommodate P-RNAV terminal area procedures. As such, capacity and environmental benefits can be obtained e.g. specific SIDs/STARs can be designed to accommodate different environmental requirements for night and day operations.

Viewed from a European strategic perspective, the application of P-RNAV in ECAC Terminal Airspace is to be viewed as a pragmatic step towards RNP RNAV application which will form the basis of RNAV terminal area procedures in the future.

 Next Page