A method for controlling a pressurized mattress system, said pressurized mattress system having an upper surface for receiving a patient thereon, said pressurized mattress system including: at least one zone (100A-100D) having at least one inflatable air bladder, a pressure sensor for measuring a zone air pressure of said at least one zone, a plurality of interface pressure sensors disposed on an upper surface of said at least one inflatable air bladder, each of said plurality of interface pressure sensors measuring an interface pressure at a discrete location along said upper surface of said at least one inflatable air bladder, a source of pressurized air, and a controller for receiving signals from said pressure sensor and said plurality of interface pressure sensors and for controlling the flow of pressurized air to/from said at least one inflatable air bladder based on said signals, wherein said controller calculates a zone interface pressure for said at least one zone based on said signals from said plurality of interface pressure sensors, said method comprising the steps of: a) inflating said at least one inflatable air bladder to an initial zone air pressure; b) calculating a zone interface pressure and storing as a first zone interface pressure; c) reducing the zone air pressure by a predetermined first value; d) calculating a zone interface pressure and storing as a second zone interface pressure; e) repeating steps b) - d) until the second zone interface pressure exceeds the first zone interface pressure by a predetermined amount; f) storing said second zone air pressure as a zone air pressure at a bottoming point; g) increasing the zone air pressure by a predetermined second value; characterized by the further steps of: h) calculating a zone interface pressure and storing as a third zone interface pressure; and i) comparing said third zone interface pressure to said first zone interface pressure and inflating said at least one zone to the zone air pressure associated with the lower zone interface pressure. at least one zone (100A-100D) having at least one inflatable air bladder, a pressure sensor for measuring a zone air pressure of said at least one zone, a plurality of interface pressure sensors disposed on an upper surface of said at least one inflatable air bladder, each of said plurality of interface pressure sensors measuring an interface pressure at a discrete location along said upper surface of said at least one inflatable air bladder, a source of pressurized air, and a controller for receiving signals from said pressure sensor and said plurality of interface pressure sensors and for controlling the flow of pressurized air to/from said at least one inflatable air bladder based on said signals, wherein said controller calculates a zone interface pressure for said at least one zone based on said signals from said plurality of interface pressure sensors, said method comprising the steps of: a) inflating said at least one inflatable air bladder to an initial zone air pressure; b) calculating a zone interface pressure and storing as a first zone interface pressure; c) reducing the zone air pressure by a predetermined first value; d) calculating a zone interface pressure and storing as a second zone interface pressure; e) repeating steps b) - d) until the second zone interface pressure exceeds the first zone interface pressure by a predetermined amount; f) storing said second zone air pressure as a zone air pressure at a bottoming point; g) increasing the zone air pressure by a predetermined second value; a) inflating said at least one inflatable air bladder to an initial zone air pressure; b) calculating a zone interface pressure and storing as a first zone interface pressure; c) reducing the zone air pressure by a predetermined first value; d) calculating a zone interface pressure and storing as a second zone interface pressure; e) repeating steps b) - d) until the second zone interface pressure exceeds the first zone interface pressure by a predetermined amount; f) storing said second zone air pressure as a zone air pressure at a bottoming point; g) increasing the zone air pressure by a predetermined second value; characterized by the further steps of: h) calculating a zone interface pressure and storing as a third zone interface pressure; and i) comparing said third zone interface pressure to said first zone interface pressure and inflating said at least one zone to the zone air pressure associated with the lower zone interface pressure. h) calculating a zone interface pressure and storing as a third zone interface pressure; and i) comparing said third zone interface pressure to said first zone interface pressure and inflating said at least one zone to the zone air pressure associated with the lower zone interface pressure.