<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by crAAzy:
If a segment or flight in your itinerary only has 2 classes of service (first/coach) then you get first class...so you get "bumped up".</font>
From the OWE rules:-
<font face="Verdana, Arial, Helvetica, sans-serif" size="2">For flights where no first or business class is available or offered, first class passengers will travel in business / economy class and business class passengers will travel in economy class. The fare for the highest class used applies and no refund will be given.
Exception – for services within/between the USA and Canada where no business class is offered business class passengers may
book and travel in first class subject to availability.</font>