As many of you are probably aware, the reason the major US airlines operate these regional subsidiaries is to keep costs down. The pilots and flight attendants operating these flights are on significantly lower pay scales. The airlines are able to get away with this because of their scope clauses. I believe American’s agreement with pilots cuts off at 76 seat aircraft. In other words, if a plane has at most 76 seats, it can be operated by a regional carrier, while if it has more seats than that it has to be operated by mainline crews.