[UPDATE, Feb. 8, 2017: Southwest plans to complete by May 9 the second “foundational release” of the new Amadeus Altéa reservation system. That would cover passenger check-in and boarding, baggage check-in and other operational functions. The initial release in December 2016 allowed for domestic U.S. ticket sales. The airline described that as a “virtually flawless” transition. Future phases would add…