A GaInSb concentrated alloy has been solidified under microgravity conditions by using the Bridgman method during the STS 78/LMS mission. A numerical simulation is used in order to explain the behavior of the axial In solute distribution as revealed by analysis of the flight sample. Measurements of the gravity level onboard the Shuttle, show a significant increase of the g-jitter amplitude, 90 min after the start of the growth process, which is correlated with perturbation of the chemical segregation. A numerical analysis of the g-jitter effect on the chemical segregation in the case of concentrated GaInSb alloy solidification is performed by varying the amplitude and the frequency of the residual gravity. A small effect of periodic accelerations on the solute distribution is observed only for frequencies below 10(-2) Hz. At higher frequencies, the axial and radial segregation are practically unchanged. The numerical modeling shows that the sharp increase of g-jitters accelerations 90 min after the start of the growth process, produces an increase of the convective intensity, which mixes the melt and increases the solidification temperature so that the interface jumps forward. The associated morphological destabilization of the interface is experimentally observed on the etched sample and on the longitudinal profile of solute concentration measured in the crystal. After a chemical homogenization of the melt, the controlled growth is started again with an axial concentration profile, corresponding to a Scheil's law. (c) 2004 Elsevier B.V. All rights reserved.