What is the ‘scope clause/limitation’?
The pilot unions negotiated limited number of smaller RJs that can carry their passengers, usually in the 50 and 76 seat range. Management would love to use more and bigger RJs because they’re nominally cheaper to operate than 737/A320. Once the carrier hits those limits, they can negotiate more with the union (unlikely since it means pilot jobs), buy 737s and have empty seats, or buy jets inbetween an RJ and 737/A320 and fly them with mainline pilots. The new A220 and E195E2 are in that range, plus some others. There’s a lot more pilots at big carriers now that lived through regional jobs making crap pay, and hopefully they’re willing to hold the line on scope.
Also the economics made more sense when regional pilots made $20k/yr. Now the ATP requirements of 1500 hours total time have dried up regional applicants from puppy mill flight schools, so Regionals have been forced to up pay (and offer Rotary transition programs) to fill class seats, and also make military pilots in demand. ??????