The aircraft performance book level is established by the aircraft manufacturer and represents a fleet average of brand new airframe and engines. This level is established in advance of production. Normal scatter of brand new aircraft leads to individual performance above and below the book value. The performance data given in the Airbus documentation (Flight Crew Operating Manual) reflects this book value. The high-speed book value data is stored in the high-speed performance databases used by Airbus performance software such as the IFP, the FLIP or the APM programs.
The performance levels are measured in their variations over time. Resulting trends can be made available to the operators’ various departments, which perform corrective actions to keep a satisfactory aircraft condition.
The actual aircraft performance deterioration endows two main origins: engine performance degradation (fuel consumption increase for a given thrust) and airframe deterioration (seals, doors, slats and flaps rigging, spoilers rigging, etc...). A starting point is required so as to monitor the trend of the performance deterioration. The baseline level is an aircraft performance level retained as a reference to get the trend of aircraft performance deterioration. Most of the time the baseline is established at the aircraft entry into service during the first flight or delivery flight. The baseline can be above or below the book level as a result of above-mentioned scatter.
Flight Operations & Line Assistance Getting to Grips with Aircraft Performance Monitoring
BACKGROUND
2. AIM OF THE AIRCRAFT PERFORMANCE MONITORING
Results of aircraft performance monitoring are used to reach the following
objectives:
-To adjust the performance factor for:
.
the computerized flight plan,
.
the FMS predictions and
-To monitor the aircraft condition periodically in order to analyze the trend of a given tail number or of a whole fleet,
-To identify the possible degraded aircraft within the fleet and take care of the necessary corrective actions:
.
Maintenance actions
.
Route restrictions
-To demonstrate the performance factor for ETOPS which may be used instead of the 5% factor imposed by regulations.
It also allows operators to perform various statistics about fuel consumption and as such is a good aid to define the operators’ fuel policy.
As a general rule, regulation requires to take into account “realistic” aircraft fuel consumption.
3. THE CRUISE PERFORMANCE ANALYSIS METHODS 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 monitoring(5)
