How can a contract that has been signed in the past 12mths be worthless?
Pilots are hired under the terms of a CBA negotiated with the union. Each CBA is up for renewal after x years. Even after the CBA comes up for renewal, its terms remain valid until it is replaced by a new CBA.
Spirit's CBA was up for renewal three years ago. During these three years, negotiations have gone nowhere. The union said management dragged its feet to avoid committing to a new CBA, management said it wasn't true. Either way, the union got tired of waiting after three years, called in a strike and there's now apparently an agreement on a new CBA.