  We introduce analogs of the Kempf--Laksov desingularizations of Schubert
bundles in (non-necessary Lagrangian) symplectic Grassmann bundles. In this
setting, these are (possibly singular) irreducible flag bundles that are
birational to Schubert bundles, and can be described as chains of zero-loci of
regular sections in projectivized bundles. The orthogonal analogs are also
presented. We immediatly derive universal Gysin formulas for isotropic Schubert
bundles from these very constructions.
