I am curious about a flight path marker display/system/implentation such as Denti describes. I can understand a crude system using AoA and actual pitch attitude, but why? Inertial platforms these days are extremely reliable and accurate and cheap compared to the stuff we had in the 70's and 80's.
The inertial flight path vector we had was no sierra inertial with respect to Mother Earth. No AoA inputs, no baro inputs. I mean, why? Sheesh. The inertial patform was also used to present basic attitude reference accurate to maybe 0.01 of a degree. Add the accelerometers and get the flight path vector, maybe to 0.02 of a degree ( figure 1 milliradian or so). Add the HUD pitch lines from the basic platform and it was a simple matter to see if you were climbing or descending. Made night takeoffs and missed approaches very comfortable when cross-checking the steam gauges.
Guess I better look up all the avionics on these "new" jets, ya think?