(1) A GPS-defined Non-Precision Approach must be interrupted, if the GPS PRIMARY LOST message is displayed.
POSITION UPDATE
In the case of an obvious and major map shift, indicated by messages, such as "CHECK A/C POSITION, FM1/FM2 POS MISMATCH", the aircraft position may be updated on the MCDU PROG page. There are two possible techniques:
The recommended technique is to update the FMS over a beacon by pressing the UPDATE prompt once estimating that the aircraft overflies the beacon using the associated needle. The potential error induced is approximately 4 to 5 nm. When the position update is achieved, the EPE is automatically set to a higher value and the navigation accuracy is low.
The second technique consists of updating the FM position, when flying over a Point/Bearing/ Distance (P/B/D) with reference to beacon raw data (Needle + Distance) rather than the beacon itself. The potential for error is far less when the distance is greater than 60 nm. The flight crew will keep in mind the potential 180 ° error on bearing.
SUPPLEMENTARY INFORMATION
NAVIGATION ACCURACY
FM position update in flight
SUPPLEMENTARY INFORMATION
NAVIGATION ACCURACY
Intentionally left blank
SUPPLEMENTARY INFORMATION
ZFW - ZFCG ENTRY ERRORS
GENERAL
Applicable to: ALL
Before engine start, the FMGC computes the aircraft’s Gross Weight (GW) and Center of Gravity (CG). After engine start, both the Flight Envelope Computer (FE) and the Fuel Control and Monitoring Computer (FCMC) calculate the GW and CG.
These GW and CG values provide information for:
? Aircraft GW and CG displays
? FM predictions and speeds
? The AP/FD and flight control laws
? The calculation of the VS1G
? The calculation of the characteristic speeds (VLS, F, S, GD), for display on the PFD
? CG control
If a ZFW or ZFWCG is not correctly entered on the INIT B page of the MCDU, this results in calculation errors.
TECHNICAL BACKGROUND
Applicable to: ALL
To calculate the GW and CG:
1. The pilot enters the ZFW and ZFWCG on the INIT B page of the MCDU.
2. The FCMC calculates the GW and CG by taking into account the ZFW and ZFWCG (entered on the INIT B page of the MCDU), and the quantity of fuel in each tank.
The GW and CG, calculated by the FCMC, are:
? Used by the FCMC to regulate the center of gravity
? Transmitted to the ECAM SD for display
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本文链接地址：A330/A340 机组训练手册 FCTM Flight Crew Training Manual 2(68)
