The influence of the US scope clause on the regional jet OEMs is significant. The following chart illustrates how the sheer size of the US regional market dominates. Any regional jet OEM seeking high production volumes must ensure the aircraft offered can operate within the US market.
Even if an OEM decided to ignore the US market, and say decide to focus on the Asia/Pacific instead, it would mean trying to earn a return from a 500 aircraft segment. The risks are too great and an OEM could not replace every aircraft in that market in a competitive environment.
The issue that drives the regional jet OEMs then is the scope clause hurdle that exists in the US. This rule, designed to protect mainline airline pilots, ensures that regional jets are limited in capacity. The rule in 2016 calls for a seat limit of 76 and MTOW no greater than 86,000 pounds.