-Engine.
 In addition to these models, some items of information are provided to
 compute characteristic speeds and miscellaneous data.
 Up to 6 different engine types for 3 different aerodynamic models can be
 included in the FMGC software.

 (1)
 Aircraft aerodynamic (Aero) model The aircraft aerodynamic model consists of sets of drag coefficients used in aircraft equations of motion for the entire range of aircraft configurations and flight conditions. Two sets of drag coefficients are given depending on the configuration : one for clean configuration, the other for a high lift configuration.

 (a)
 The lift coefficient is computed from the equation of motion on the lift axis.

 (b)
 Drag coefficient The drag is computed from a standard drag coefficient plus a deviation. The standard drag coefficient uses tables function of the lift coefficient, the Mach number and the aircraft configuration at reference Reynolds number. The deviation takes into account effects of speedbrake extension, landing gear extension, included in approach and landing configuration, center of gravity deviation from reference position, Reynolds number and trim drag due to asymmetrical thrust. The speedbrake correction models an half speedbrake extension only.

 (2)
 Engine model The engine model describes the interrelations between thrust, thrust settings, and fuel flow for a particular engine under given operating conditions. This model is used by the performance function in conjunction with the aircraft models to solve the aircraft steady state equations of motion. Following data are given :

 (a)
 Function of thrust setting parameter and Mach number:

 -
Corrected net thrust

 -
Corrected fuel flow The equation of motion used for optimization and prediction computations will make use of net thrust.

 (b)
 Function of Mach number, altitude and temperature:

 -
Max climb setting

 -
Max continuous

 -
Idle ratings

 -
Idle margin or idle rating

 (c)
 Function of Mach number

 -Corrected windmill thrust
 -Airflow.

 (3)
 Miscellaneous data:

 -takeoff speeds (F-S-O)
 -engine out climb and drift down speeds (0)
 -speed envelope depending on the speed mode
 -maximum altitude
 - optimum climb, cruise and descent speeds

 -holding speeds
 -time, fuel and distance for flight phases such as preflight, takeoff and go around phases
 -distance, speed correction and approach definition
 -alternates predictions (fuel and time)
 -center of gravity computation
 -repressurization control law for cabin pressure
 -wind model.

R **ON A/C 106-149, 151-199, 211-299, 301-399, 401-499,
 Post SB 22-1089 For A/C 151-199,211-212,
 FLIGHT PLAN/DATA BASE - DESCRIPTION AND OPERATION
_________________________________________________
 1. General
_______ The Flight Management System (FMS) may contain three different flight plans. The first, called ACTIVE flight plan (F-PLN), is used as a basis for primary display on the Multipurpose Control and Display Unit (MCDU), the Navigation Display (ND), for deviation signal evaluations, radio navigation autotuning, performance predictions, fuel planning and lateral and vertical guidance when coupled to the autopilot. The second is the SECONDARY flight plan. It is used for display and for preparing a second departure procedure before takeoff, for routing comparison, for prediction comparison or evaluations, for preparing the next flight leg. The third is the TEMPORARY F-PLN. It is a copy of the active flight plan which has been changed according to the pilot's action on the MCDU. It is created for display when the active flight plan (primary or alternate) is changed through the LAT.REV pages only. Each flight plan is composed of the same elements (Ref. para. 2.A) :
 -primary F-PLN (from origin to destination)
 -alternate F-PLN (from primary destination to alternate destination). After a long-term power interrupt on ground, all defined flight plans are saved. At power up, the A/C STATUS page is displayed (Ref. para. 2.E.), showing the aircraft model stored by the FMS as well as the data base status. In order to initialize the system, the crew must insert an ACTIVE flight plan on the INIT page (Ref. para. 2.B). The revisions of the flight plan in the lateral dimensions are described in para. 2.C. while the revisions of the vertical flight plan are described in para. 2.D. Para. 2.E. deals with the navigation and the performance data bases. The navigation data base contains all the elements used to define the various elements of any F-PLN as well as the navigation aids in a region. The data are requested by each airline, to the equipment manufacturer, under the format defined in ARINC 424-14. The equipment manufacturer forms these data in a format acceptable by the Flight Management and Guidance Computer (FMGC). In addition to the customized nav data base, the crew may create up to 20 new waypoints, 20 new navaids, 10 new runways and 5 new company routes. The performance data base contains all the data necessary to the system to execute all the performance functions (optimum speeds, predictions along the F-PLN, etc...).
　
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