Rate airlines by profitability not size.

Could be four categories. Small, Medium, Large & Mega airlines. You would only be competing against similar sized airlines and might even decide not to grow too big and not move up a category.

You might not even need four categories - the most profitable and least leveraged airline is perhaps the best investment choice, so it should rate highly even if it is small. I like running small airlines; I'd really like a measure like this looking at crafting an investment rather than bulldozing the skies. Perhaps airlines should have share prices which reflect things like 12 month profitably, rating and reputation averages, but which can neither be directly used nor sold as an investment nor offer dividends - they only show another measure of management skill than size.

You might not even need four categories - the most profitable and least leveraged airline is perhaps the best investment choice, so it should rate highly even if it is small. I like running small airlines; I'd really like a measure like this looking at crafting an investment rather than bulldozing the skies. Perhaps airlines should have share prices which reflect things like 12 month profitably, rating and reputation averages, but which can neither be directly used nor sold as an investment nor offer dividends - they only show another measure of management skill than size.

While I do tend to end up with a Mega airline, often because someone tries to muscle in on my area of operation, I do like to see how profitable I can make my airline. In S2, where it takes longer to grow, have managed to get profitability over 35%. You would need more than one category as the larger an airline gets the lower it's profitability rating.

I think size and profitability need to be the balance you choose to make on a single spectrum: much like the real world, where the most profitable investments are often not in the largest companies which too often seem to be kept alive by bankruptcy protection or investment banks throwing good money after bad. I suspect the ability to thrive as enormous airlines in AE is an emergent system property based on its limited set of rules and human abilities to use them, rather than a generally inherent property of airline management in the real world. It would be good if AE had a declining ability to find or afford loans as loan ratios increased, a much decreased ability to profit from leasing, and random events with substantial impact that occured as a function of fleet size (i.e. 1% chance per year per aircraft) such as a crash, or global grounding of an aircraft model for safety inspections, or a pilot strike, or CEO resignation, or massive corruption fine. Then we can see profitability as a worthwhile goal, and system threats which are seriously challenging to deal with.