Dynein axonemal assembly factor that regulates the transport and activation of ciliary outer dynein arms (ODAs), which are the main force generators in cilia (PubMed:33632841). Essential for cilia movement and motility (PubMed:33632841). Inhibits dyneins by reducing the affinity of ODAs for microtubules and hence inactivating the dyneins in the cytoplasm; the inhibition is relieved once dyneins enter the cilia (By similarity). May act as an effector for ARL3 (PubMed:22085962). {ECO:0000250|UniProtKB:Q22YU3, ECO:0000269|PubMed:22085962, ECO:0000269|PubMed:33632841}. This is the function of DNAAF9 (dynein axonemal assembly factor 9, ENSG00000088854).