I haven't seen this before and search yielded nothing recognizably similar in past threads.

I did a UA website search this morning for a one-way revenue ticket MDT - SMF. The date of travel was April 18, 2012. Many possible itineraries were returned. Right near the top of the list was this one.

MDT - ORD on UA 287 (an A319) connecting to
ORD - SMF on UA 381 (an A320)

Five or six itinerary choices farther down the list was this one.

MDT - EWR on UA 4384 (a Q200) connecting to
EWR - ORD on UA 297 (an A320) connecting to
ORD - SMF on UA 381 (an A-320)

Since I'm trying to use my RPUs I checked the fare buckets. On the MDT - ORD - SMF itinerary UA381 had R1 and RN1. However, on the MDT-EWR-ORD-SMF UA381 had R2 and RN2. Same flight on the same day with the same search but different upgrade award space shown?!?

When did the itinerary start affecting upgrade inventory space in this manner? I've never seen such a thing before.

On the same flight number from AAA to CCC with stop at BBB I've seen differing space from AAA nonstop to CCC as compared to AAA-BBB and BBB-CCC. But I've not seen this. Besides UA381 is a non-stop ORD-SMF.

Did the routing through EWR cause this? It would seem so. If yes then why?

Inquiring minds want to know.

CB