I’ve heard in several places. It’s possible that it’s all emanating from APC, but that seems unlikely.

I’m not sure subfleets matter to PBS. It matters for seniority to those in the various fleets, but the computer is simply tasked with crewing all the tails as efficiently as possible. So perhaps you need 300 total tails worth of savings created by crew being scheduled by PBS to offset the cost of running the system.

But that’s just reaching elbow deep.