getting to grips with fuel economy(8)

 
The most important part of the take-off weight from an airlines point of view is the payload (passengers and freight). Generally the weight of passengers, carry-on baggage and checked bags are defined in the operating rules by the authorities such as the JAA or the FAA. Most operators use standard weights although other values may be used if they can be statistically demonstrated through surveys. In general there is not much an operator can do to change the situation. However they should be aware of the rules and their validity. If the weights do not seem appropriate then an operator should consider conducting a survey.
As each freight consignment is weighed, the only influence it can have on fuel economy is its location and hence the aircraft CG.
4.2.5  EMBARKED FUEL

  
Fuel is loaded onto the aircraft to be used as follows: 
 
1. Start-up Fuel

2. Taxi Fuel

3. Trip Fuel

4. Reserve Fuel

5. Fuel for Transportation

6. APU Fuel

 
In order to avoid unnecessary fuel weight, the flight must be planned very precisely to calculate the exact fuel quantity to be embarked. Flight planning should be based on aircraft performance monitoring by taking into account performance factors derived from specific range variations. In addition the planning should be based on the appropriate optimized techniques using the best achievable routing and flight levels.
 
More detailed information on this subject is given later in this brochure.
4.3 FLIGHT PLANNING

 
The fundamental requirement for achieving fuel economy and reduction of operating costs is a quality Flight Planning System. 
 
A good flight planning system will produce an optimized route, in terms of track, speeds and altitudes, which meets the operator’s economic criteria.  This track and vertical profile must be normally achievable in operation, given the constraints of ATC, climb rates, descent rates, etc.
 
Climb, cruise and descent techniques and cruise flight levels should be optimized in accordance with the operator’s criteria, for both the sector and the diversion. This is covered in much more detail in this brochure.
 
It will be based on good quality data (temperature, wind, aircraft weight, payload, fuel uplift, etc)
 
It will be use the correct aircraft performance and will include an individual aircraft performance factors derived from an ongoing aircraft performance monitoring (APM) program (see “Getting to Grips with Aircraft Performance Monitoring”).
 
Having established the climb, cruise and descent techniques, it should be verified from time to time that the aircrews are using these techniques
 
The fuel reserves will be based on a policy that aims at obtaining the minimum values required within the regulations.
　
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