A pneumatic sheet feeder is selectively actuable to acquire a sheet from a stack and transport the sheet towards a take-away nip. The feeder includes a feedhead having an acquisition surface substantially aligned with the take-away nip. A sensing apparatus detects three separate distances between the stack and the acquisition surface at three separate locations over the stack. The stack is then tilted based upon the distances sensed by the sensors. In embodiments, the feedhead has two sensors, and moves so that the third distance can be measured by one of the sensors. In other embodiments, the feedhead includes three sensors for measuring each of the distances.