  We measure the Hall conductivity, $\sigma_{xy}$, on a Corbino geometry sample
of a high-mobility AlGaAs/GaAs heterostructure in a pulsed magnetic field. At a
bath temperature about 80 mK, we observe well expressed plateaux in
$\sigma_{xy}$ at integer filling factors. In the pulsed magnetic field, the
Laughlin condition of the phase coherence of the electron wave functions is
strongly violated and, hence, is not crucial for $\sigma_{xy}$ quantization.
