  X-ray transients provide unique opportunity to probe accretion regimes of at
a vastly different accretion rates. We analyze a collection of the RXTE
observations (Galactic Center scans, ASM monitoring and a pointed observation)
of enigmatic transient source high mass X-ray binary V4641 Sgr and argue that
they broadly support the hypothesis that giant September 1999 outburst was
associated with an episode of super-Eddington accretion onto the black hole.
During the outburst an extended optically thick envelope/outflow has been
formed around the source making the observational appearance of V4641 Sgr in
many aspects very similar to that of SS433. These results suggest that objects
like V4641 Sgr and SS433 indeed represent the class of objects accreting matter
at a rate comparable or above Eddington value and the formation of an
envelope/outflow is a generic characteristic of supercritical accretion.
  When the accretion rate decreased the envelope vanished and the source short
term variability and spectral properties started to resemble those of other
galactic black hole candidates accreting at a rate well below the Eddington
value. Interestingly that during this phase the source spectrum was very
similar to the Cygnus X-1 spectrum in the low state inspite of more than order
of magnitude larger X-ray luminosity.
