  We study the jet and counterjet of the powerful classical double FRII radio
galaxy Cygnus A as seen in the 5, 8 and 15-GHz radio bands using the highest
spatial resolution and signal-to-noise archival data available. We demonstrate
that the trace of the radio knots that delineate the jet and counterjet
deviates from a straight line and that the inner parts can be satisfactorily
fitted with the precession model of Hjellming & Johnston. The parameter values
of the precession model fits are all plausible although the jet speed is rather
low (< 0.5 c) but, on investigation, found to be consistent with a number of
other independent estimates of the jet speed in Cygnus A. We compare the masses
and precession periods for sources with known precession and find that for the
small number of AGN with precessing jets the precession periods are
significantly longer than those for microquasars.
