  The Galactic microquasar SS433 occasionally exhibits a major flare when the
intensity of its emission increases significantly and rapidly. We present an
analysis of high-resolution, almost-nightly optical spectra obtained before,
during and after a major flare, whose complex emission lines are deconstructed
into single gaussians and demonstrate the different modes of mass loss in the
SS433 system. During our monitoring, an initial period of quiescence was
followed by increased activity which culminated in a radio flare. In the
transition period the accretion disc of SS433 became visible in H-alpha and HeI
emission lines and remained so until the observations were terminated; the
line-of-sight velocity of the centre of the disc lines during this time behaved
as though the binary orbit has significant eccentricity rather than being
circular, consistent with three recent lines of evidence. After the accretion
disc appeared its rotation speed increased steadily from 500 to 700 km/s. The
launch speed of the jets first decreased then suddenly increased. At the same
time as the jet launch speed increased, the wind from the accretion disc
doubled in speed. Two days afterwards, the radio flux exhibited a flare. These
data suggest that a massive ejection of material from the companion star loaded
the accretion disc and the system responded with mass loss via different modes
that together comprise the flare phenomena. We find that archival data reveal
similar behaviour, in that when the measured jet launch speed exceeds 0.29c
this is invariably simultaneous with, or a few days before, a radio flare. Thus
we surmise that a major flare consists of the overloading of the accretion
disc, resulting in the speeding up of the H-alpha rotation disc lines, followed
by enhanced mass loss not just via its famous jets at higher-than-usual speeds
but also directly from its accretion disc's wind.
