Board Thread:Unanswered Questions/@comment-26298928-20150812062204/@comment-25045164-20150827144526

Stat bars aren't meant for comparison between aircraft, especially with different Cst and categories. I've never upgraded any of my planes past level 8 but from the way I see it, the bars are only to show how much upgrade you've poured into your planes. In other words, they're progress bars for upgrade.