Abstract: A foil air bearing for a rotatable shaft comprises a plurality of discrete air chambers disposed in a circumferential array. Each of the chambers has a radially displaceable radially inner wall for positioning a bearing foil disposed radially inwardly thereof. A like plurality of valves control the flow of pressurized air to the air chambers, respectively. Sensors respond to radial deflection of the shaft so as to control the flow of pressurized air to the chambers, selectively, thereby to compensate for radial deflection of the shaft.