  We revisit the paradigm of the dependency of jet power on black hole spin in
accreting black hole systems. In a previous paper we showed that the luminosity
of compact jets continuously launched due to accretion onto black holes in
X-ray binaries (analogous to those that dominate the kinetic feedback from AGN)
do not appear to correlate with reported black hole spin measurements. It is
therefore unclear whether extraction of the black hole spin energy is the main
driver powering compact jets from accreting black holes. Occasionally, black
hole X-ray binaries produce discrete, transient (ballistic) jets for a brief
time over accretion state changes. Here, we quantify the dependence of the
power of these transient jets (adopting two methods to infer the jet power) on
black hole spin, making use of all the available data in the current
literature, which includes 12 BHs with both measured spin parameters and radio
flares over the state transition. In several sources, regular, well-sampled
radio monitoring has shown that the peak radio flux differs dramatically
depending on the outburst (up to a factor of 1000) whereas the total power
required to energise the flare may only differ by a factor ~< 4 between
outbursts. The peak flux is determined by the total energy in the flare and the
time over which it is radiated (which can vary considerably between outbursts).
Using a Bayesian fitting routine we rule out a statistically significant
positive correlation between transient jet power measured using these methods,
and current estimates of black hole spin. Even when selecting subsamples of the
data that disregard some methods of black hole spin measurement or jet power
measurement, no correlation is found in all cases.
