The volume-to-extinction ratio (ζ) is an important aerosol property, allowing to relay gravimetric and optical quantifications, widely used in remote sensing and in climate models. The ζ parameter is affected by the microphysical properties of aerosol particles, including their size, shape and composition . This study presents a novel, synergistic approach combining airborne in-situ observations and ground-based remote sensing to study this parameter during dust events originating in the Middle East and Saharan regions, and examine its variability and general estimation uncertainty. The data were collected during the 2021 Cyprus Fall Campaign and the 2022 ASKOS campaign in Cabo Verde. The combination of observations offered vertically-resolved observations of the particle size-distribution and volume-to-extinction ratio. The findings of this study reveal significant variability in the ζ parameter and the effective radius across different events and regions. During Middle East dust events in Cyprus the observed average ζ was the lowest with ζ = 0.53 ± 0.24 <em>μm</em>, whilst for a Saharan dust case in Cabo Verde observations showed the highest values with ζ = 1.14 ± 1.01 <em>μm</em>, both at the dust layer altitude. The analysis highlights large discrepancies compared to AERONET-derived values and previous literature, especially in the presence of coarse and giant particles. Scattering computations allowed to evaluate the experimental results and provide insights into the role of particle asphericity. Atmospheric model simulations also showed discrepancies, mainly due to assumptions that neglect larger particles. These findings suggest that improve dust representation in models is essential for accurate climate assessment.