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7. Using Required Navigation Performance

Using Required Navigation Performance

The analysis and conclusions contained in this case study are those of the authors alone and do not necessarily represent the point of view of the Government of Canada.

Organization
WestJet Airlines Ltd.

Major Findings
WestJet's use of Required Navigation Performance lowered fuel use and greenhouse gas emissions.

Project Timeline
March 2006 to March 2007

Please note that some figures such as cost savings on fuel are based on data from the period that this project took place.

Introduction

uired Navigation Performance (RNP) is a satellite global positioning system that uses a network of satellites to precisely locate and guide aircraft via their onboard navigational computers.

While RNP was developed to address scheduling and safety problems at airports with poor weather and surrounding mountainous terrain, it offers real benefits to all airports. Benefits of RNP can include:

• More reliable (repeatable), predictable flight paths
• Optimized approaches and departures, resulting in lower thrust settings and noise levels
• Time and fuel savings
• Shorter route distances
• Higher takeoff weights/reduced thrust
• Reduced training costs
• Consistent ‘common instrument approach' for all operations
• Fewer weather-related diversions or cancellations
• Flight safety enhancement

WestJet undertook a project to examine the benefits of RNP with financial assistance from Transport Canada's Freight Sustainability Demonstration Program.

Project Description
WestJet evaluated RNP, using it for 22 of its Canadian destination airports for its fleet of Boeing 737 aircraft.

 

Project Goals and Objectives
The objective of this project was to show how RNP reduces fuel use and greenhouse gas (GHG) emissions and provides other operational benefits.

Project Methodology
The project developed RNP approaches for 22 Canadian airports served by WestJet. An approach template was prepared for each, based on the aircraft navigational equipment, satellite technology and software developed jointly by WestJet and the RNP developer, Naverus. Each template was submitted to nav canada for approval.

As each airport template was approved, it was entered into WestJet's operational specifications. RNP training for flight crews required one day of simulator and one day of ground training.

Once RNP was operational, flight data recorder information was used to compare fuel burn and flight time for flights before and after RNP. The flight time saved by using RNP was used to calculate fuel savings.

As the study went on, data collection was refined to improve accuracy.

Results
RNP technology was implemented at all of the 22 airports targeted for this project, and was used at all of the airports to varying degrees between March 2006 and March 2007. Table 1 summarizes the results the first ten months of RNP operation for 16 Canadian airports.

   Table 1 Fuel savings and related and greenhouse gas reduction

Approaches	Fuel saving (litres)	C02 reduction (tonnes)	Methane reduction (kg)	Nitrous oxide reduction (kg)
9,716	743,000	1,895	5.8	18.5

Naverus prepared a case study for Kelowna (YLW) that showed the flight paths before and after RNP implementation. As shown in Figures 1 and 2, RNP resulted in defined flight paths that reduced longer flight distances linked to navigational corrections.

Figure 1 Tracks before RNP                         Figure 2 Tracks using RNP
(116 arriving flights to Runway 34)               (128 arriving flights to Runway 34)

While RNP enabled both constant rates of descent and precision approaches that significantly reduced GHG emissions, constant rate of descent was the larger contributor. The large savings shown in Table 1 grew as more airports were configured for RNP.

There are several other potential savings that were not measured during this project. For example, when WestJet uses the full range of RNP procedures, aircraft will no longer make non-precision approaches - which may allow a reduction in required training time. Once consistent routing efficiencies can be quantified, over block-times (the time allotted by the route planners to complete the journey from the time the aircraft pushes back from the gate to the time it arrives at the gate at its destination) may be reduced. This in turn may result in less fuel use, increased aircraft use and, more sales opportunities.

Based on the benefit of RPN, WestJet intends to implement it for international destinations as flight regulations in those countries are updated.

Conclusion
This project demonstrated the benefits of using RNP in WestJet aircraft configured to facilitate approaches to 22 Canadian airports. During the initial ten-month monitoring period, the use of RNP reduced fuel consumption by 743,000 litres, reduced CO₂ emissions by 1,895 tonnes and offered other potential cost savings through operational improvements.

RNP allows WestJet to provide more accurate and reliable approaches to the Canadian airports it serves. It makes approaches more efficient through direct line approaches and constant rate descents.

WestJet intends to expand the use of RNP to all Canadian airports where there are potential benefits and to get approval to use the technology at US and international destinations.

Additional Information

• Naverus
• WestJet

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Date modified:

2012-02-16

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