  The experimental study of magnetic flux penetration under crossed magnetic
fields in Bi2212:Pb single crystal performed by magnetooptic technique (MO)
reveals remarkable field penetration pattern alteration (flux configuration
change) and superconducting current anisotropy enhancement by the in-plane
field. The anisotropy increases with the temperature rise up to $T_m = 54 \pm 2
K$. At $T = T_m$ an abrupt change in the flux behavior is found; the
correlation between the in-plane magnetic field and the out-of-plane magnetic
flux penetration disappears. No correlation is observed for $T > T_m$. The
transition temperature $T_m$ does not depend on the magnetic field strength.
The observed flux penetration anisotropy is considered as an evidence of a
strong 3D - correlation between pancake vortices in different CuO planes at $T
< T_m$. This enables understanding of a remarkable pinning observed in
Bi2212:Pb at low temperatures.
