Per the union email just sent:

Retroactive Pay Methodology

The company has informed the Association that in regards to retroactive pay referenced in the "Implementation of New Pay Scales & Retroactive Pay" LOA, they will be calculating retroactive pay based on pilots' actual hours for months that retro pay is owed. The company has also communicated that by the end of the month, appropriate pay rates will be implemented and applicable retroactive pay will be paid out. This action will comply with the signed LOAs.