2 Max Max Altitude
_ It is the minimum altitude found with respect to the same criteria as defined above except the case of maximum altitude before buffeting with a margin of 0.2 g.
(b)
Maximum altitude in engine out case It is the minimum altitude found with respect to the following criteria:
-
the maximum altitude which can be attained with a flight path angle of 1.6 percent minimum (one engine failed) or 0.5 percent minimum (two engines failed) with the operating engines at Maximum Continuous Thrust and anti ice on
-
the maximum altitude which can be reached before buffeting with a 0.3 g margin
-
the maximum altitude which can be flown with a speed higher than Green Dot and lower than VMO/MMO
-
the maximum certified altitude.
(c)
Optimum altitude The optimum altitude is displayed on the PROG page. It is computed by taking into account the active strategic mode (including the cost index if it is ECON), the predicted aircraft and atmospheric conditions. The optimum altitude is limited from above by first, the maximum altitude (Ref. Para. 1_ and 2_ above), and then the condition of a minimum of 15 min. flown in cruise at that altitude. (Ref. Fig. 042)
(8) Maximum holding time
(a) Last exit UTC If the holding fix is the FROM or TO waypoint, the FMGC computes the latest time when the A/C has to leave the hold so as to satisfy the fuel reserve requirements (corresponding to EXTRA = 0). It is displayed on the HOLD page. (Ref. Fig. 043)
Time and Fuel to Exit the Hold
Figure 043
(b) Logic for display of the TIME TO EXIT message The conditions to display the message are:
-Nav mode is engaged
-hold is the next or active leg
-last exit UTC is available
-and IMM EXIT has not been selected.
Considering: Delta T = last exit UTC - predicted UTC of next
passage over exit fix,
3 cases are possible:
-
Delta T > time to fly a complete holding pattern: no message
-
Delta T < time to fly a 360. turn: message immediately displayed
-
Delta T bounded between a 360. turn and a complete holding pattern: message is displayed if the A/C has started but not completed the first turn of the holding (i.e. 1 min. after overflying the fix).
The message, when displayed, is removed if it is cleared by the pilot or if the IMM EXIT prompt is selected or if NAV mode is disengaged.
(9) Wind/temperature model
(a) Wind model The pilot can enter a single trip wind on the INIT A page, prior to engine start. This trip wind is entered as an effective wind component to be realized, on average, during the trip from origin to destination. It is typically used in preflight for producing fuel and time estimates in the absence of wind entries. Once winds have been entered for any one of the climb, cruise, or descent (excluding alternate wind) profiles, the trip wind is no
R longer considered in the wind modeling for the remaining flight
R (even if all winds are cleared). Forecast wind profiles are constructed for three distinct segments:
-
the climb segment, defined from the origin to the initial T/C, which can be entered on the CLIMB WIND page
-
the cruise segment (which includes steps), defined from the T/C to the T/D, which can be entered on the CRUISE WIND pages
-
the descent segment, defined from the T/D to the destination, which can be entered on the DESCENT WIND page. The destination wind can also be entered on the PERF APPR page.
Forecast wind is determined at each waypoint and pseudo waypoint along the F-PLN for display on the F-PLN B page. The origin and destination winds are entered on the CLIMB and DESCENT WIND pages by entering a wind at GRND or a wind within 400 ft of the respective origin or destination elevation.
The destination wind can also be entered on the PERF APPR page. The entered values are displayed on the F-PLN B page as a forecasted wind at the origin or destination waypoint. If an origin or destination wind is not entered and trip wind is not used, the forecast wind at the origin or destination will be direction/velocity, where direction is identical to that of the lowest climb or descent wind entry (up to T/C or T/D) and velocity is zero.
(b) Temperature model R Temperature modeling is based on the computation of an R International Standard Atmosphere (ISA) temperature deviation
(ISA DEV) profile, based on the difference between an entered or
measured Static Air Temperature (SAT) and an ISA temperature at a
given altitude.
Temperatures are measured in degrees centigrade.
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