747-400 Fmc Vnav Path
Can someone explain to me how the VNAV works when you do a runway extension from the Final Fix.
If you are tracking for straight in appr and do a runway extension from a point on the ILS the VNAV seems to calculate a 3 deg slope back from the way-point you have extended from.
However if you are approaching the runway from a reciprocal position (downwind leg) and you do the runway extension from the same fix the VNAV seems to draw a path from the aircraft's current altitude to the height displayed on the fix. Obviously this path is of no use to anyone.
Why is it so????