The Charlotte Observer ran on its front page Saturday an Associated Press story about how airlines are cutting back on the number of 50-seat and smaller aircraft they operate, which in turn means that some communities are losing their scheduled air service. It’s a good story as far as it goes but it does not get into one of the critical issues going forward: scope.

As always, the issue is easier to imagine when you’re looking at a concrete example. Like, well, US Airways flights from Charlotte. On November 10, 2011, the airline and its regional partners operated 625 flights. By aircraft type, these broke down as:

US Airways mainline (Airbus and Boeings): 275
Large regional jets (CRJ700, CRJ900, E175s) seating 67 – 86, have first class: 145
50-seat regional jets: 151
50-seat turboprop: 30
37-seat turboprop: 24
(Total: 625)

Now everybody that follows the airline biz expects that over time the number of aircraft seating 50 or less will go down. It doesn’t take much brains to come to this conclusion, as such regional jets aren’t in production anymore.

If you said that the obvious solution is for US Airways and friends to simply replace their 50-seaters with bigger regional jets that seat 67+, that may not be so easy to do. The scope clause in US Airways’ contract with its pilots says that the airline’s regional partners can only operate 110 such large RJs. And yes, they do currently fly 110. Getting approval to add more would depend upon a new labor contract.

US Airways is actually better situated when it comes to operating such large regional jets than some other airlines. American Airlines is limited to 47 big RJs. Continental’s pilot contract effectively forbids them, causing Continental to opt for modern 70-seat turboprops instead. Like US Airways, American and Continental (as part of the merger integration with United) are negotiating new pilot contracts. The specifics of those deals, including what specific types of aircraft regional partners can operate and in what quantities, along with the price of fuel, will go a long way to determining how many 50-seaters are in the air five years from now, and how many communities lose some or all of their air service.