There is a definite problem with the Elevation Graph (right click/map tool/ elevation graph) in the 2 latest versions 51 and 52 of Mission Planner for planes.
They get the altitude wrong and put it well below ground level for part of the flight.
See attached screen shots of plan for 14 mile low level flight in terrain follow mode over hilly terrain. 1.3.50 gets it right but 1.3.52 makes out it’s well below ground at various points of the flight.
I have MP 1.3.52 and tested your mission altitude concern.
Although I do not advise your reliance in graphic 2D display,
I have tested your altitude concern with 1.3.52 using Google Earth.
So far, I think MP 1.3.52 using Relative ‘verify height’ is functioning correctly.
When a mission is created, the mission can be projected into Google Earth (GE) via KML Export
This feature available in Flight Plan page, with ‘View KML’ link located in top right of page (below Coordinate display).
When the KML file is opened in GE, a set of layers are presented.
Advice -> Deselect the ‘onground’ layer, and all individual waypoints.
The ‘WPs’ layer is the one you use for 3D display.
Ensure the ‘WPs’ layer is projected with altitude in Absolute Format.
(Right click, Properties, Altitude, Pull-down menu = Absolute).
Important to note: If consecutive waypoints cross a ridge of higher altitude,
the flight path will collide with the ridge.
If so, add an additional waypoint atop the ridge.
When flying in mountains,
It is advisable to view your intended mission in 3D, not 2D.
In this 3D fashion, ridge collision mistakes can be easily identified.
ensure your home altitude is set correctly before opening the elevation graph. if this is incorrect, then it is all incorrect.
I have set home altitude correctly and checked everything and the Elevation Graph is definitely showing wrong in versions 51 and 52 of Mission Planner for planes when flying in terrain mode.
Today I uninstalled version 50, loaded 52 and it showed my flight elevation completely wrong, in effect flying under the ground.
I reloaded version 50 and it shows it correctly. Have a look at the 2 links in my original post above. This is the same flight plan in the 2 different versions, one correct and one all over the place.
Definitely something not right with it.