Check the flight number. If it's an 800- or 900-series flight number, it's a continuation of an overseas flight (with change of gauge at the international gateway such as SFO). These flights have NC availability, though you get to sit in the F cabin. It's so that through pax from overseas can be upgraded Y->NC on "direct" flights with one flight number. One of the most famous cases for this is UA881/882 BOS-ORD-NRT-BKK and vv.
I have a confirmed NC (seated in F cabin) SFO-BOS for this coming October on a 757 on UA862.
Last edited by wxguy; Feb 28, 2010 at 4:39 pm