Abstract: A sensor for attachment to an inflatable air cell cushion to detect a change in immersion depth and bottoming out of the user seated on the cushion. The sensor includes an airflow conduit for attachment to the cushion inflation tube. The airflow conduit comprises a cylindrical body having a longitudinal inner bore. There is an opening through the conduit body in fluid communication with the bore. A transducer is positioned at the opening to detect changes in air pressure within the airflow conduit. The transducer is operatively connected to a warning light, an audible sensor and a mode set button. The functions of the electronic components are preprogrammed into a computer chip. A battery powers the sensor. The recited components are secured within a housing.