Is this a joke? Honest...

There are so many factors that it's not a real question. Very often the passenger buys a ticket from, say, RIC-PHL (an example of a roughly 300 mile trip on the airline I fly with) but that passenger is probably not staying in PHL. That passenger is flying RIC-PHL-FRA or RIC-PHL-DTW or RIC-PHL-LAX. So there is no way of knowing what, or if, there is a break even point. It is all how the airline decides the break it down. The passenger doesn't pay the ticket on a per-leg basis.

This is why it is not quite so cut and dry as to whether or not the 50-seat so-called "RJ" is profitable or not. Nothing is as simple as it looks, including the economics of the CRJ-200.

Finally, pilots are not accountants or business folks for the most part. We all are pretty sure we could run the business better, but really, probably we couldn't. So I doubt there is anyone here who can really answer your question. Why don't you go to www.airlinemanagementforums.com and I am sure they will have the answer.