  We study the smectic $A$-$C$ phase transition in biaxial disordered
environments, e.g. fully anisotropic aerogel. We find that both the $A$ and $C$
phases belong to the universality class of the "XY Bragg glass", and therefore
have quasi-long-ranged translational smectic order. The phase transition itself
belongs to a new universality class, which we study using an $\epsilon=7/2-d$
expansion. We find a stable fixed point, which implies a continuous transition,
the critical exponents of which we calculate.
