Safety culture among mental health workers is essential, especially in developing countries where workplace safety seems neglected. However, few studies have provided detailed psychometric analyses of convenient safety instruments with practical relevance for the healthcare industry in the Sub-Saharan African context. We sampled 574 (54.4 % females, 45.6 % males) mental health workers from three Specialist Psychiatric Teaching Hospitals in Ghana. Initially, we collected data using adapted items from Edkins and Coakes’ 25-item Airline Safety Culture Index (ASCI). Consequently, we conducted a Confirmatory Factor Analysis (CFA) using the Diagonally Weighted Least Squares estimator. We also used the item reduction analysis (Gradual Response Model) to reduce the adapted 25-item scale to 11 items (Modified Safety Culture Index, MSCI- 11). Finally, we conducted reliability analyses (alpha and omega) for the MSCI-11. We observed that the data in the CFA showed adequate fit indices [χ2 (df = 44, N = 574) = 223.752, p < 0.001; CFI = 0.975; TLI = 0.968; RM- SEA = 0.084 (CI 90 % 0.074- 0.096); SRMR = 0.063]. The MSCI- 11 is parsimonious and has good reliability estimates [α = 0.853 (95 % CI 0.835 – 0.870) and ω = 0.853 (95 % CI 0.837- 0.087)]. Future studies should use additional cross-validation in other high-risk jobs to generalise the new scale.