  We use the traditional approximation to describe oscillations with
frequencies comparable to the angular rotation rate. Validity of this
approximation in application to main-sequence B stars is discussed. Numerical
results regarding mode stability and visibility are presented for a model of
the Be star HD 163868. For this object, Walker et al.(2005) detected a record
number of mode frequencies using data from the small space telescope MOST. Our
interpretation of these data differs from that of Walker et al. In particular,
we interpret peaks in the lowest frequency range as retrograde g modes. We find
instability in a large number of modes that remain undetectable because of
unfavourable aspect and/or effect of cancellation. There is no clear preference
to excitation of prograde modes.
