  In this note, we derive an ordinary differential equation for outgoing light
rays in the spacetime of a spherically symmetric contracting dust cloud. The
violation of strong cosmic censorship is equivalent to the existence of a
solution blowing up at the centre of the symmetry. As an application, we
reprove the generic violation of strong cosmic censorship for a dust cloud
first proved by Christodoulou. We also derive a similar equation for a
spherically symmetric dust cloud in the case of positive cosmological constant
and show the generic violation of strong cosmic censorship in this case.
