I am not an expert in KML, just implementing the fix from the google group here; it is possible it must to be in both locations but at least for Google Earth it loads correctly with it set only within .
I'll submit a PR when I get a chance; for now I wanted to document this.
The line setting altitudeMode for KML tracks here https://github.com/muccc/iridium-toolkit/blob/master/mkkml#L262 should actually be within and moved before Line 265. As-is, google earth will load the tracks with altitudeMode clampToGround (default).
I am not an expert in KML, just implementing the fix from the google group here; it is possible it must to be in both locations but at least for Google Earth it loads correctly with it set only within.
I'll submit a PR when I get a chance; for now I wanted to document this.