Alternate XXXX

performance Initialisation Route Departures and Arrivals VNAV Fix Legs Hold Progress Menu Navigation Radio

Each of the four alternate airports shown on the ALTN page 1/2 have a related XXXX ALTN page. The XXXX ALTN pages show specific data about alternate airports, the route used for a diversion, and the conditions upon which the ETA and fuel calculations are based. All data on the page is related to the alternate airport shown in the page title.

Three route options to the airport can be selected:
  • DIRECT TO - direct to alternate
  • OFFSET - flight plan route with an offset
  • OVERHEAD - flight plan route to a waypoint then direct to alternate

    • The selected route option is identified by <SEL>. ETA and fuel remaining are calculated based on the selected option. Selection of a route option for one alternate selects the same route option for the other three alternates.

    VIA DIRECT TO - Push - selects present position DIRECT TO alternate route option. All flight plan waypoints are deleted.
    VIA OFFSET - Push:
  • With scratchpad empty, selects OFFSET route option
  • with offset data in scratchpad, enters offset data. Does not select option
    • Entry and exit to the offset is the same as for the RTE page offset. All flight plan waypoints are kept.
    VIA OVERHEAD - Push:
  • With scratchpad empty, selects OVERHEAD option
  • with overhead data in scratchpad, enters overhead data. Does not select route option
    • Displays active waypoint in flight plan.

    The waypoints up to the selected or entered overhead waypoint are kept, then routing is direct to the alternate airport. All waypoints after overhead waypoint are deleted.

    Enter any waypoint in the active or modified route.
    ENG OUT - This prompt performs the same function as described on the cruise page in the FMC Cruise section. It can be selected before or after the diversion is selected.
    ALTN - Displays the ALTN 1/2 page.
    ALT - Entry of any valid altitude or flight level into this line causes a re-computation of ETA and arrival fuel. Altitude entries do not become part of the diversion modification. Altitude entries apply to all four alternates.

    Displays the altitude for which ETA and arrival fuel are calculated.

    The scratchpad displays the message UNABLE ALT, if the entry is above maximum altitude or the top of climb point for divert is after top of descent point for divert.
    Speed - Entry of speed or Mach number into this line causes a re-computation of ETA and arrival fuel. Speed entries do not become part of the diversion modification. Speed entries apply to all four alternates.

    Speed modes available are:
  • ECON (economy)
  • LRC (long range cruise)
  • EO (engine out)
  • EO LRC (engine out long range cruise)
  • CO (company speed)
  • any CAS or Mach
    • WIND - Entry of data into these lines causes a re-computation of ETA and arrival fuel. A separate wind entry may be made for each of the four alternates.

    Displays the estimated average wind for the divert route.

    Valid entry is a direction in degrees true/speed in knots from 1 to 999.
    ALT/OAT - Entry of data into these lines causes a re-computation of ETA and arrival fuel. A separate ALT/OAT entry may be made for each of the four alternates.

    Displays the OAT for a specific altitude.

    Valid entry is an altitude/temperature in degrees C.
    XXXX ETA/FUEL - Displays the calculated airport ETA and arrival fuel based on the selected route, altitude, and speed shown on this page.
    XXXX DIVERT NOW - This prompt performs the same function as described on the ALTN 1/2 page.

    Note: After a divert is executed, the XXXX ALTN page data is not updated until all CDUs change to a page other than the XXXX ALTN page.

    Standard | 11.43.18 | Holding>