Attack of the Cybermen - S22-E1
Corrected entry: The TARDIS comes under "enormous g-force", implying it is free falling through an atmosphere. However the Doctor later says something about it not begin able to breathe in a vacuum, with would imply they were still in space. (However, planets aren't the only things to produce gravity, suns also do, but suns tend to be fairly hot, and nothing is said about heat...).
Correction: The TARDIS is not falling through an atmosphere (if it were, the Doctor and Peri would be floating inside). It is accelerating out of control.