getting to grips with aircraft performance 如何掌握飞机性能 2(27)

.
 FR = Final Reserve Fuel

.
 Add = Additional Fuel

.
 XF = Extra Fuel

Figure I1 illustrates the different fuel quantities and associated flight phases of a typical trip.
The following operating conditions should be taken into account for each flight:
.
Realistic airplane fuel consumption data.

.
 Anticipated weight.

.
Expected weather conditions.

.
Air traffic services’ procedures and restrictions.

1.1.1.1. Taxi Fuel
“AMC OPS 1.255 Taxi fuel, which should not be less than the amount, expected to be used prior to take-off. Local conditions at the departure aerodrome and APU consumption should be taken into account.”
Taxi fuel is usually a fixed quantity for an average taxi duration. For the A320 for example, it is equal to 140 kg (300 lb). This corresponds to a 12-minute average taxi fuel. Based on statistics or evaluation, the taxi duration and taxi fuel may need to be adjusted.
1.1.1.2. Trip Fuel
The required fuel quantity from brake release at the departure airport to the landing touchdown at the destination airport, is referred to as trip fuel. This quantity takes into account the necessary fuel for:
. 
 Takeoff

.  
Climb to cruise level

.  
Flight from the end of climb to the beginning of descent, including any step climb/descent

.  
Flight from the beginning of descent to the beginning of  approach,

. 
 Approach

.  
Landing at the destination airport

1.1.1.3. Contingency Fuel
Contingency fuel is the greatest of two quantities:
.
The fuel necessary to fly for 5 minutes at 1500 feet above the destination airport at holding speed in ISA conditions

.
One of the following quantities:

.
5% of trip fuel,

.
 With airworthiness approval, 3% of trip fuel with an available en route alternate airport*,

.
With airworthiness approval, the necessary fuel to fly for 15 minutes at 1500 feet above the destination airport, at holding speed, in ISA conditions; the Operator must have a program to monitor fuel consumption on each individual route / aircraft combination and must use the program to statistically calculate contingency fuel

.
The required fuel to fly for 20 minutes, based upon trip fuel consumption, provided the operator has a fuel consumption monitoring program for individual airplanes and uses the resulting data for fuel calculation.

* Appendix 1 to AMC-OPS 1.255 explains how to reduce contingency fuel from 5% to 3%:
“AMC-OPS 1.255 If an en-route alternate is available within a circle having a radius equal to 20% of the total flight plan distance, the centre of which lies on the planned route at a distance from the destination of 25% of the total flight plan distance, or at 20% of the total flight plan distance plus 50nm, whichever is greater”
　
中国航空网 www.aero.cn
航空翻译 www.aviation.cn
本文链接地址：getting to grips with aircraft performance 如何掌握飞机性能 2(27)