Opportunities – Air Transport

Improve fleet management and flight logistics

Air traffic management is already highly efficient in Australia by global standards. However, fuel efficiency opportunities may still exist through reviewing and optimising fleet management, flight logistics and the utilisation of jet streams.

Some examples of opportunities in this area are outlined below.

Better fleet management

Gathering and analysing data stored on the automated flight log can open up new ways for airlines to better manage and operate their fleets to save fuel and costs.

Many airlines are looking at how to choose the most fuel efficient aircraft and flight scheduling for a particular route.

Skywest has been working with Governments and local councils to reduce where feasible, the frequency of flights to regional communities being serviced by smaller turbo prop aircraft and replacing the capacity with less frequency and larger regional jet aircraft.¹

- Skywest Energy Efficiency Opportunities 2008 Public Report

QantasLink also reports that, on some regional routes, it uses Q400 aircraft that are 35% more fuel efficient than similar-sized aircraft.²

Optimise descent paths, scheduling and taxiing aircraft

Traditionally, jet airliners have approached a runway by ‘stepping down’ rather than making a smooth steady descent. This has meant that at each step, the pilots have needed to adjust the thrust of the engines. New technology means that airlines can work with air traffic control and airports to create a much smoother descent to the runway, thereby improving fuel efficiency. Use of flight management systems (FMS) to optimise descent paths can save between 121 and 246 litres of jet fuel per descent compared to a traditional approach.¹

Airlines can also work with air traffic service providers to reduce the burning of fuel while in holding patterns. Adjusting the timing of flights also enables aircraft to achieve better fuel efficiency through reducing the length of holding periods.

Fuel can also be saved by using a single engine to taxi the aircraft when landed at the airport. Studies suggest that one minute of single engine taxiing per aircraft flight saves 430,000 litres of fuel annually.²

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Fly with or avoid jet streams

The location of jet streams is vital in aviation. In addition to cutting time off the flight, it also nets fuel savings. In Australia, flights from west to east can take advantage of tailwind jet streams, whilst flights east to west need to avoid the jet stream as much as possible.

There is potential to improve fuel efficiency for international flights by raising the quality of forecasting of jet streams, notably over oceanic and sparsely populated areas.¹

Improve flight logistics

Improvements in air transportation logistics, chiefly from information technology, are expected to save 5–10% of system fuel at negative cost.¹

State of the art aircraft now have the technology to enable flight paths to be optimised in real time in response to changing weather patterns. Re-routing in flight can save significant fuel on international long hauls, where upper-level winds, jet streams and other meteorological parameters can change quickly. Such real-time flight logistics technologies can be used when airspace restrictions are lifted.

Flying at higher altitudes can also reduce drag and increase fuel efficiency. Regional Express has reported investigating this opportunity.

Current standard cruise altitudes are being reviewed by flight operations performance engineering with the view to introducing variable standard altitudes to allow for higher levels at lighter loads. The object of the review is to increase the average cruising height level across the entire network which will reduce average fuel burns and hence carbon emissions. Case studies conducted on Syd – Lismore and Syd – Ballina routes projected over a year is anticipated to produce savings of approx 16,600 litres.²

- Regional Express 2009 Energy Efficiency Opportunities Public Report

The way an aircraft is loaded can also significantly impact the fuel efficiency of a flight. If the aircraft’s load is not balanced, then the pilot will need to trim the aircraft continually throughout the flight to compensate. Operating an aircraft in trim mode uses more fuel.

Combining optimal flight logistics with optimal take off and landing techniques can yield significant fuel efficiency savings, as in the following example:

Emirates Airline has participated in the INSPIRE (Indian Ocean Strategic Partnership to Reduce Emissions) program, with two test flights (one from Dubai to Brisbane, the second from Perth to Dubai). The aim of the INSPIRE initiative is to gauge the improved environmental impact of a ’perfect flight’: minimising on-ground delays, using expedient taxiing and runways, conducting gradual climb and descent paths, while flying direct optimum routes based on existing meteorological and airspace conditions. The results from these two flights alone gave a combined total saving of over 6,250 litres of fuel and more than 16,000 kg of carbon dioxide emissions.³

- Transport & Logistics News, 2011

Retrofit aircraft to achieve weight reductions

Numerous opportunities exist to reduce weight and improve the fuel efficiency of aircraft. They include ensuring the optimal amount of fuel carried is sufficient for each flight, so as to minimise weight and drag, to exploring options to retrofit and redesign aircraft using lighter engines and composite-fibre components.

Some examples of opportunities in this area are outlined below.

Reduce aircraft cabin weight

It is possible to reduce weight throughout the cabin of a passenger aircraft through a variety of strategies:

• Reduce weight in the food, drink and catering equipment carried.
• Use lighter seat, carpets and types of in-flight TVs; e.g. LED TVs are lighter than the older CRT TVs.
• Replace cargo containers with lightweight options.
• Replace in-flight magazines with electronic reading options via the in-flight TV (saving up to 70 kg; an extra passenger equivalent).
• Replace the library of operational flight manuals in the cockpit with a laptop computer containing the same information.
• Manage weight restrictions for on-flight, carry-on luggage.

Cumulatively, these steps can significantly reduce the fuel demands over a calendar year.

 Qantas’ program of weight reduction focuses on two main streams – “Above Wing” which targets reducing the weight and volume of cabin product on board the aircraft and “Below Wing” which involves the technical removal of weight from equipment and furnishings on board. This program has achieved an average of 119kg reduction per aircraft.¹

- Qantas Airways Limited Energy Efficiency Opportunities Program 2009 Public Report

Optimise fuel requirements to reduce weight

A number of airlines still carry fuel on aircraft for the return journey or second leg of the flight. This adds significantly to the aircraft’s weight and, consequently, impacts on fuel use during the first leg of the flight. The argument has been that fuel may cost more at the airport destination than at the airport from which the plane departed. This assumption does not stack up against a proper cost-benefit analysis.

To improve fuel efficiency, aircraft should only carry onboard the required legal minimum amount of fuel for a particular one-way trip or the first leg of a longer flight schedule. Making this change will lead to immediate net cost savings that improve the bottom line.

Improve aircraft aerodynamics

The two main sources of drag for aircraft are skin-friction drag and lift-induced drag. These constitute approximately one-half and one-third of the total drag, respectively, for a typical long-range flight at cruise conditions.

Significant levels of research and testing show that riblets, large eddy break-up devices, hybrid laminar flow technology, and innovative wing-tip devices offer the greatest potential for reducing drag. Aircraft aerodynamic performance improvement can also be obtained through trailing-edge optimisation, control of the shock boundary layer interaction and control of boundary layer separation.[1.  J Reneaux (2004) Overview on Drag Reduction Technologies for Civil Transport Aircraft. Presented at the European Congress on Computational Methods in Applied Sciences and Engineering]

Changes to reduce drag can offer significant fuel efficiency savings. In their 2008 Public Report year for the Energy Efficiency Opportunities program, Regional Express Holdings Ltd reported they are currently exploring installing winglets to reduce drag.

Fuel consumption savings are estimated at 5%. Estimated installation cost of AUD 8 million over 40 aircraft with yearly savings of AUD 1.99 million. 4yr Payback period expected¹.

- Regional Express 2008 Energy Efficiency Opportunities Public Report

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Improve electrical energy efficiency

Although it may not show up as a major component of total costs, electrical efficiency in aircraft makes a difference. Essentially, all electricity used on a plane is generated using an auxillary power unit (APU). These units tend to use a relatively inefficient gas turbine which is run on expensive jet fuel. More energy efficient types of gas-powered auxiliary power units are available on the market, but they do have substantial up-front costs and the energy efficiency dividend is not great. Therefore, other options should be explored.

In flight energy efficiency measures can be cost effectively applied in areas such as lighting and in-flight TV systems.

When aircraft are docked at airports, it is also more efficient to source electricity from the airport itself than from the plane’s own power unit. Qantas has recently reported  significant savings in this area.

Auxiliary Power Unit (APU) reduction program focuses on utilising ground based infrastructure (Power and Pre-Conditioned Air) where available to minimise APU usage across its network. This operational change has achieved savings of over 1.25 megalitres of jet fuel or 45,960 GJ of energy in 2008/9.¹

- Qantas Airways Limited 2009 Energy Efficiency Opportunities Public Report

Invest in new engines and aircraft

Investing in new, more efficient engines is a wise strategy to improve fuel efficiency. There are aircraft engines on the market that are 10–15% more fuel efficient than best technologies available ten years ago. Engines with still greater fuel efficiency are expected by 2020. Similarly, upgrading airline fleets to more efficiently designed aircraft can yield significant fuel savings.

Combining these measures can generate significant energy efficiency gains in the short and longer terms.¹

Some examples of opportunities in this area are outlined below.

Retrofit engines

Significant advances have been made in the fuel efficiency of aircraft engines over the past decade. For instance, Rolls Royce say that the fuel consumption of one of its engine types has reduced by 12% between 2000 and 2010. The company predicts a further 10–15% improvement in fuel efficiency using open rotor engines.¹

Technologies required to achieve significant engine-weight reductions include:

• improved materials (composites and high-temperature materials in particular)
• improved aerodynamics (to reduce the number of turbine and compressor stages)
• increased turbine entry temperatures (to reduce airflow and core engine size required for a given power output).²

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Upgrade aircraft fleet

Advances in engine technology, materials science and aerodynamic performance will enable new fuel efficient planes to offer a 15–35% fuel efficiency improvement over today’s models by 2020 and up to 50% improvement by 2050 .¹ For example, the use of advanced composites in the new Boeing 787 Dreamliner (now in operation) will help to reduce fuel consumption by 20%.²

In 2010, Qantas reported³ it was investing significantly to purchase 150 new airliners over the next eight years that are 20% more fuel efficient compared to its current similar sized aircraft. This will help Qantas achieve much of its 2020 fuel efficiency improvement target.

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