Hi Chris,
Yes - bwpatric has the solution. This topic was discussed in another thread some time back called "Why are my Wucka Ducks upside down?" (yes that was the subject title
)
The situation you are facing is only when using Orientation > "aligned" in the Animation Path. By default, paths are drawn left-to-right, or moreover clockwise. If you drew you path arc starting clockwise from the top, you'd find that the plane object would not flip. When using "aligned" the object is instructed to be aligned with the path, so its orientation must be set... because you have decided to drew your path right-to-left and down the bottom, Opus can only do what it is instructed to do...and that is "align" the object correctly to the path. Therefore it will "correct" the orientation when "aligned", and will seem to flip the object. This is not an error... it just takes some pre-thought when using paths.
The solution as "bwpatric" has posted is the easiest answer to resolve your problem when you are drawing a path actually upside down. In your IMP, if you "mirrored" the path, then "flipped" it, it would be starting from the top and its direction would be right-to-left. You would of course need to rotate in the editor the plane vector object so it's facing the correct way. (try it and you will see it works as expected.)
I have attached a screenshot, of using "aligned" in Opus. It may at first seem confusing, since it was demonstrated for the "Wucka Duck" thread, but you should be able to follow it. Please remember the issue is ONLY when using "aligned" in paths.
In the screenshot, take a look at 'Path 1' > "Previewed" and you will note the duck has flipped upside down, but in essence it is doing exactly what it should since "aligned" was used.
Hope this helps.