End_of_Descent
5th Mar 2004, 22:43
I wonder whether someone can provide some insight in the finer details of the new 737NG Vertical Situation Display (VSD). (link) (http://www.boeing.com/commercial/aeromagazine/aero_20/vsd.html)
For reference, the VSD has a Boeing PFD-style altitude tape on the left hand side and an airplane symbol at the current altitude next to it. Now, would that altitude tape in the VSD show barometric altitude or geometric (with GPS etc based corrections) altitude?
Since a terrain profile view is also shown on the VSD, geometric altitude would be the obvious choice since the airplane position would be display relative to MSL, similar to terrain data.
However, geometric alt might disagree with the altitude tape on the PFD then (possible confusion?). On the other hand, a vertical profile of the FMC route is shown together with (barometric) altitude constraints - which would make a barometric alt reference useful.
So, what is actually shown? Anyone?
EoD
For reference, the VSD has a Boeing PFD-style altitude tape on the left hand side and an airplane symbol at the current altitude next to it. Now, would that altitude tape in the VSD show barometric altitude or geometric (with GPS etc based corrections) altitude?
Since a terrain profile view is also shown on the VSD, geometric altitude would be the obvious choice since the airplane position would be display relative to MSL, similar to terrain data.
However, geometric alt might disagree with the altitude tape on the PFD then (possible confusion?). On the other hand, a vertical profile of the FMC route is shown together with (barometric) altitude constraints - which would make a barometric alt reference useful.
So, what is actually shown? Anyone?
EoD