CAPA doesn't apparently have the significant capabilities and other services required to support it's own members, why else would the APA need to come to ALPA to get those capabilities.

"We are very pleased to announce that our talks with the Air Line Pilots Association (ALPA) have borne fruit in many areas where we have pledged mutual cooperation, including ALPA’s generous offer to provide APA access to ALPA’s extensive capabilities in the area of economic and financial analysis and other related services. It is safe to assert that the relationship between ALPA and APA is the best it’s been in decades. Working together, we can advance the profession far more than acting as competitors." APA ltr