<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by Radiocycle:
If the crews are waiting for another a/c that has been rescheduled (rolled back) then couldn't nwa crews spend many hours waiting for the next trip?</font>
No.
I don't think you understand the concept of rolling hubs (which is surprising considering you started this topic).
The point of a rolling hub schedule is to get an aircraft to turn as efficiently (read: quickly) as possible at both the hub and the spoke station. The point is to have aircraft in the air more and less ground time. Therefore, there's no 'rolling back' of any flights.
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Another point against a MEM rolling hub is that MEM is in a good location to serve the Southeast US. On AA, if rolling hub schedules don't work (i.e. 2.5-3 hr waits), then one can still go through STL (or even ORD, MIA) without too much of a detour. With MEM, the alternate hub is not there. If someone wants to fly say from AUS to TPA, and the connection through MEM 2.5-3 hours, then chances are the passenger will fly someone else (via DFW, IAH, ATL, etc).