Antarctic ice shelves often contain narrow, curvilinear tracts of thin ice, termed ice-shelf channels, that impact ice-shelf stability. Their surface depressions appear prominently in satellite imagery and form an interesting morphology of unknown origin, the more so because the processes leading to ice-shelf channel formation are unclear. Here we investigate the origin of ice-shelf channels at the Roi Baudouin Ice Shelf, which have previously been attributed to ice overriding sediment ridges formed by long-term deposition in subglacial water conduits. However, due to a limited radar dataset at the time, the shape and upstream extent of the basal obstacles was unclear, making it difficult to pinpoint the exact type of the subglacial landform. In 2019, we revisted this location with an improved airborne ultra-wideband radar and collected a number of across-flow profiles upstream of the grounding line. Consistent with previous suggestions, we find that the basal obstacles shrink in size with increasing distance from the grounding line until they are invisible about 10 km upstream. However, the change in size is gradual in the first 8 km, and then very abrupt in the last 2 km. Variations in basal reflectivity indicate the existence of patches of subglacial water in all profile lines. Once fully evaluated, this rich dataset has the potential to classify the basal landform and hence shed light on the origin of ice-shelf channels and their impact on ice-shelf stability.