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7. Aircraft Fuel Reduction Initiatives

Aircraft Fuel Reduction Initiatives

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
Air Transat A.T. Inc.

Major Finding
12 energy-saving practices were introduced. These resulted in a 5% reduction in annual fuel consumption.

Project Timeline
October 2004 to December 2005

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

Introduction

In 2003, Air Transat launched an initiative to reduce the fuel consumption of its aircraft, with funding from Transport Canada’s Freight Sustainability Demonstration Program.

Twelve fuel saving measures related to engineering, ground services, flight planning, flight operations and catering weight were identified and implemented.

These measures resulted in fuel savings of approximately 5% per year and a corresponding annual reduction (5%) in greenhouse gas emissions (CO₂, CH₄, and NO_x).

Project Description

Air Transat engaged Flight Sciences to help identify, implement, monitor and measure fuel saving practices for Air Transat’s fleet of 11 Airbus A310 aircraft, and 4 Airbus A330 aircraft. Between October 2004 and December 2005, Air Transat identified and tested 12 fuel saving measures.

Project Methodology

The project was divided into three major phases:

1. Analysing current operating procedures;
2. Identifying ways to reduce fuel consumption; and
3. Implementing and monitoring fuel-saving measures.

The third phase was completed with funding from Transport Canada.

At the outset of the project, a Fuel Management Team was established. With the assistance of Flight Sciences, the team analysed operating procedures and identified several ways to significantly reduce fuel consumption.

Steering committees were formed to implement specific measures. New procedures (best practices) were documented and training introduced the changes at the operational level. Implementation took place over a period of 18 months and the Fuel Management Team met monthly to review progress and direct the steering committees.

Several methods were used to monitor the fuel-saving initiatives. Some (aerodrag, engine waterwash, auxiliary power unit (APU) usage, lighter weight tires and catering weight) were tracked through operational reports. Others were tracked from flight plans that record flight particulars such as routing, flight time, payload, aircraft weight, number of passengers, cargo weight, fuel weight and flight cost index. Several of the fuel reduction measures related to the cost of carrying weight (COW).

The COWs used to calculate fuel savings for measures that reduced weight are as follows:

Aircraft	Fuel penalty for 1 kg for 1 year (per kg per year)	Cost to carry 1 kg for 1 year (per kg per year)*
A310	59.04 US gal.	US$ 131.28**
A330	42.71 US gal.	US$ 94.96

Other measures depend on how pilots fly the aircraft (idle reverse, economic climb, takeoff profile and APU usage) and can be monitored by means of different versions of ACARS (aircraft communication addressing and reporting system) that Air Transat has installed on all aircraft. Because of the different versions of ACARS, the systematic tracking for all flights was a challenge. Air Transat is examining ways to acquire data systematically from all flights.

Finally, some measures (single engine taxi, potable water levels, and weight of load containers) were monitored through Air Transat audits made regularly throughout the project.

Project Results

Discussion

1. Aerodrag

   Roughness on aircraft exterior surfaces increases drag and fuel consumption. A program was developed to routinely inspect aircraft exterior surfaces to identify and correct defects such as chipped paint, scratches and damaged seals. Aerodrag inspections were added to the Type A checks made on all aircraft every four weeks and necessary repairs were made.

   Based on published information on aircraft performance deterioration, it was estimated that better care of exterior surfaces reduced the annual fuel consumption by 0.41 %. It was considered that inspection and repair costs were small in relation to the savings.

2. Engine waterwash

   Regular engine water washing was introduced to remove accumulated dirt. This cleans inside the engines while they are still on the aircraft wings and allows them to burn fuel more efficiently.

   For Air Transat, the trial wash times were set for Spring and Fall because the aircraft fly less in these seasons and washing during Canadian winters is not recommended. (Carriers in warmer climates engine wash up to four times per year.) Making allowance for the cost of acquiring the washing equipment, biannual engine cleaning reduced the annual fuel consumption by 0.42 %.

3. Lighter-weight tires

   Air Transat installed lighter weight tires on its aircraft without a decrease in performance, safety or service life and without additional cost. The new tires are 6 kg lighter than the ones they replaced and save 48 kg per aircraft. Based on Air Transat’s COW figures, this change reduced annual fuel consumption by 0.02%.

4. Potable water

   Air Transat used to operate aircraft with full potable water containers even though less was needed for shorter flights.

   This initiative looked at the impact of carrying less water on flights to Southern destinations. The first stage analysed water use and determined how much was really needed for its flights. Some extra water was added to make sure there would be no shortages en route.

   For most flights, the amount of water needed per flight was based on the water containers being refilled at the southern destinations for the return flight. More water was needed for flights to Mexico, as enough water needs to be carried for both the outbound and the return flights. Once Air Transat knew the amount of water needed for each voyage, charts were installed in all aircraft to guide handlers on how much water was needed for a given flight.

   This measure reduced weight by at least 100 kg per aircraft, and reduced annual fuel consumption by 0.09 %.

5. Auxiliary Power Unit usage

   This initiative sought to reduce Air Transat aircraft’s use of the auxiliary power units (APUs) that provide aircraft with electricity, heating and air conditioning when on the ground and not connected to ground power.

   

   The best process was for an aircraft stationed at an airport that offered ground power to start its APU about 15 minutes before take off (when the ground power unit was removed). For arrival, the best process was to connect the aircraft to ground power no more than five minutes after it reached the gate. If an aircraft arrived at an airport that did not provide ground power and the aircraft was on a turnaround (bringing passengers to their destination and returning other passengers to Canada), the APU ran during the average turnaround period of approximately one hour and thirty minutes.

   In some cases, the APU may be used for a longer period of time, for example, to warm the cabin on a cold morning before the first flight. Even in theses cases, however, APU use should average 20 minutes per flight as compared to the current average of 90 minutes per flight.

   Flight Sciences calculated that a 70-minute reduction in APU use saves 73 US gallons of fuel per flight for A310 aircraft and 84 US gallons per flight for A330 aircraft, for a potential annual fuel saving of about 0.20 %.

   Since many of Air Transat’s flights are to airports that do not provide ground power, the target of 20 minutes was not realistic and was increased to average 60 minutes. Air Transat has reduced the average APU usage to about 60 minutes per cycle, which reduces annual fuel consumption by 0.10 %, about half the amount that was first expected. Reducing APU use has been the hardest improvement to implement. Initial targets were not met, and work is continuing to monitor and reduce use.

6. Load container weight
   

   Before the fuel reduction program, Air Transat was using both lightweight and heavy ULDs (unit load devices) for storing commissary items, passenger luggage and cargo items. There are two types of ULDs: the LD3 is used for luggage and the LD6 is used for cargo. The difference in weight between the heavy and light versions of containers is 8 kg for the LD3 and 25 kg for the LD6. As a fuel reduction measure, Air Transat entered into a lease arrangement for ULDs, most being lightweight units. The lower weight reduced annual fuel consumption by 0.02 %.

7. Flight plan optimization

   In Summer 2004, Air Transat put a more sophisticated flight planning system (Flugwerkzeuge (FWZ) aviation software) in place for determining optimal flight plans. It takes into account more factors such as cost of weight, navigation charges, maintenance costs, fuel cost, navigation fees, winds, cost index and flight levels than the previous system.

   Based on industry data provided by Flight Sciences, improved flight planning reduced annual fuel consumption by 0.76 %. For example, the FWZ software reduced the fuel cost for a Montreal to Puerto Vallarta flight by C$625 compared to the system it replaced.

8. Contingency fuel

   This initiative reduced the amount of fuel aircraft carry. Pilot requests for extra fuel used to be routinely accepted by flight planning. When pilots accepted that the FZW flight management system increased the accuracy of estimating fuel needs, a new process required pilots to clearly explain any requests for extra fuel.

   

   Extra fuel was not tracked before introducing FWZ, so it was hard to measure the savings stemming from this measure. However, it is estimated that on average, pilots were loading 200 kg of extra fuel on each flight. Not carrying this weight is estimated to reduce annual fuel consumption by 0.77 %.

9. Variable cost index

   Air Transat introduced variable cost indices into the FWZ flight planning that take into account aircraft type and destination. They used to apply a cost index that was the same for all destinations and aircraft types.

   When Air Transat began to use a variable cost index for the different flights, many aircraft were operated at lower speeds. This reduced fuel burn and pollution. The variable cost index had to be relaxed occasionally during the winter, to allow some flights to fly fast enough to arrive in Montreal before the 1:00 am landing curfew.

   Using variable cost indices reduced annual fuel consumption by about 1.29 %.

10. Single-engine Taxi

    This initiative implemented single-engine taxi between the gate and the runway where possible - not all airports allow it and some winter conditions make it problematic. Although this was easy to implement, some pilots who were used to double engine taxiing resisted the measure. Single engine taxiing is thought to be safe and feasible for 90% of Air Transat flights. Even when conditions allow, single-engine taxi is not systematically practiced so pilots are reminded of how this practice helps save fuel and protect the environment. Air Transat may equip all aircraft with instruments to better track results. To date, single-engine taxiing has reduced annual fuel consumption by 0.40 %.

11. Flight operations

    This initiative looked at flight techniques that are proven to be more fuel-efficient. Altogether, these measures reduced annual fuel consumption by 0.31 %. Transport Canada approved these techniques, which were then implemented and included in the Air Transat Standard Operating Procedures manual as follows:

    • Idle reverse thrust after landing: This procedure reduces the use of reverse thrust to slow an aircraft on landing. Noise levels, engine wear, and fuel consumption are reduced by using idle reverse thrust and no auto brake when landing on an uncontaminated runway of more that 8,000 feet. Immediately after the touchdown of main landing gear, the reverse levers are pulled to the idle position. The aircraft is left to slow down and then manual braking is applied. This measure reduced fuel consumption by 0.09 %.
    • Take-off profile: ICAO has approved two take-off climb profiles: the Noise Abatement Departure Procedure 1 (NADP1) and the Noise Abatement Departure Procedure 2 (NADP2). The latter allows aircraft to retract the flaps and accelerate at a lower altitude with flaps retracted. This reduces drag and improves aircraft efficiency, reducing fuel consumption and lowering exhaust emissions. Air Transat used NADP2 wherever it is allowed, reducing annual fuel consumption by 0.10 %.
    • Economic climb: Air Transat implemented a policy that accelerates aircraft to the most economical climb speed as soon as flap retraction is complete and the aircraft turns towards the intended direction of flight. This policy can be used at about 50% of the airports where Air Transat operates. These are airports that do not restrict speed below FL100 (flight level 10,000 feet) to 250 knots. This measure reduced annual fuel consumption by 0.12 %.
12. Reduced weight of catering items

    This initiative sought to reduce the weight of catering items, without compromising customer comfort. Changes were made to select lightweight commissary items and to analyse how much various items (such as beverages, magazines, newspapers, blankets) were used, so that only the necessary amounts were carried. By making many small reductions, Air Transat removed 255 kg from A310 aircraft and 534 kg from A330 aircraft, reducing annual fuel costs 0.42 %.

Results Summary
Table 1 summarizes the results of the fuel-reducing initiatives.

     Table 1 - Summary of results

Fuel-saving Measure	Fuel reduction (% of annual fuel cost)
1. Aerodrag	0.41
2. Engine water wash	0.42
3. Lighter weight tires	0.02
4. Potable water	0.09
5. APU usage	0.10
6. Load container (ULD) weight	0.02
7. Flight plan optimization	0.76
8. Contingency fuel	0.77
9. Variable cost index	1.29
10. Single-engine Taxi	0.40
11. Flight operations	0.31
12. Reduced weight of catering items	0.42
Total calculated savings, % of annual fuel cost	5.01

Figure 1 shows graphically the cumulative effect of implementing the fuel saving initiatives adjusted to a reference flying time, with some months showing a marked improvement.

Despite the improvements, there are offsetting factors that negatively affect fuel economy. Air Transat noted an increase in fuel consumption for A310 aircraft in 2005 compared to 2004. This was linked to the fact that the fleet is aging and older aircraft tend to be less fuel-efficient. However, this decline in efficiency change would have been even greater without the fuel management efforts.

Costs and Payback

For many of the cost saving measures such as engine water wash, the maintenance cost of doing the work has been deducted from the savings. Most other changes are one-time costs that affect operational procedures, and contribute overall to better management. Therefore it can be said that the estimated cost savings reported are net amounts.

Conclusion

Air Transat, with the support of Transport Canada, undertook a sweeping review of flight operations to seek changes that would positively affect fuel costs, profits and the environment. The changes reduced fuel consumption by about 5% based on fuel costs and currency exchange rates in effect at the end of the project period in December 2005. These changes significantly reduced greenhouse gas emissions. In terms of cost reduction, the benefits will have even greater benefit as the cost of aviation fuel goes up.

Although the project is over, fuel conservation is a permanent management goal. Regular audits are made to ensure that Air Transat employees are applying best practices. The project resulted in many successes. Some initiatives fell short of their targets and improvement is continuing. In addition, Air Transat is committed to continually seeking new ways to conserve fuel. For Air Transat, the outcome is lower costs. For the environment, the outcome is a significant reduction in emissions.

Additional Information

• Air Transat
• Flight Sciences
• FWZ Flight Management
• Airline Fuel Emissions and Efficiency: International Regulations and Industry Modifications
• Aerodrag
• Aviation and the Global Atmosphere - Aircraft emissions

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Date modified:

2012-02-16

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