For the conveyor, and the work from the time the planes arrived at the hub until they left, was an issue. We had a guy, Mike Basch, Senior VP Planning, from Ra

For the conveyor, and the work from the time the planes arrived at the hub until they left, was an issue. We had a guy, Mike Basch, Senior VP Planning, from Rapistan, big in conveyor systems. I got involved for a while: I tried to do a continuous time, discrete state space Monte Carlo simulation, but it got too big to do at all easily and we dropped it. So, the hub design was done with just back of the envelope arithmetic and engineering. It worked fine for years. Over the years, the fleet scheduling problem went through various phases. The first phase that worked at all well was just my software. The last time I checked (I'd left for my Ph.D.), the package volume was high enough that one of Fred's ideas became the solution: At noon, have all the planes at distant cities. Then, in the evening, loaded up, all the planes fly to Memphis. Nearly all the flights are non-stop -- one plane, one flight, one city served. So, net, first cut, no scheduling problem at all. Maybe there could still be problems for scheduling maintenance, considerations for remote sort hubs and/or international service, but that was all after I left.