An in situ study of the plastic deformation of < 001 > single crystals of an industrial superalloy has been performed at 850 degrees C in a TEM to observe directly the micromechanisms which control the deformation under the actual temperature and stress conditions experienced by this material in aeroengines. A comparison between the creation and propagation modes of moving dislocations in the standard microstructure after annealing and the rafted microstructure after 20 h of creep at 1050 degrees C evidence the important role of the width of the gamma channels as well as the strength of the gamma/gamma' interface in controlling the shearing events of gamma' channels.