4.What I mean is that the smiths fmc works in a weird way. For each waypoint, it uses headings and continually changes it to get to the waypoint instead of working properly.
How is this different from a real aircraft ? The FMC tells the autopilot what heading to fly, and it turns to that heading, right ?
Its no different than if the pilot dialed in the heading in the MCP window, except the FMC can do faster and more accurately. In a real airliner when the aircraft is in LNAV the heading interface between the pilot and the autopilot is blocked (usually the heading window is disabled or blanked) so the autopilot does not get conflicting heading instructions.
The reason you see the heading changes in the MCP heading window with ISG1 is that there is no practical way to disable the heading window, the heading window in most FS aircraft panels is synched to the autopilot, you can't change one without also changing the other.
In V1.5 the MCP panel is customized for LNAV, the heading window will be blanked and disabled while LNAV is the active roll mode.
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