A system for active alignment of an inflatable web with respect to an inflation nozzle as the web is dispensed from a roll for serial inflation by the inflation nozzle, the inflatable web including top and bottom sheets (36a, 36b) sealed together by transverse seals to define a series of inflatable chambers having an opening between the terminal ends of the transverse seals and proximate a longitudinal edge of the web for receiving inflation fluid from the nozzle, the system comprising: a spool adapted to support the roll so that the roll rotates about the spool as the inflatable web is withdrawn from the roll; an actuator arranged to adjust the position of the roll along the length of the spool; an inflation nozzle adapted to provide inflation fluid into the openings of the inflatable chambers as the web travels along a path of travel past the inflation nozzle; a tracking sensor comprising: a sensor arm pivotally mounted at a pivot point at a given location relative the inflation nozzle, the sensor arm having a contact portion, the sensor arm adapted to pivot on the pivot point as the terminal ends of the transverse seals of the web contact the contact portion of the sensor arm; the system being characterised in that the tracking sensor comprises an analogue sensor adapted to detect the movement of the sensor arm and to generate an analogue signal varying in relation to the movement of the sensor arm, and in that the system comprises further a controller operative to receive the analogue signal and based on the analogue signal to send output to the actuator to adjust the position of the roll on the spool to maintain the transverse position of the web within a predetermined range. a spool adapted to support the roll so that the roll rotates about the spool as the inflatable web is withdrawn from the roll; an actuator arranged to adjust the position of the roll along the length of the spool; an inflation nozzle adapted to provide inflation fluid into the openings of the inflatable chambers as the web travels along a path of travel past the inflation nozzle; a tracking sensor comprising: a sensor arm pivotally mounted at a pivot point at a given location relative the inflation nozzle, the sensor arm having a contact portion, the sensor arm adapted to pivot on the pivot point as the terminal ends of the transverse seals of the web contact the contact portion of the sensor arm; the system being characterised in that the tracking sensor comprises an analogue sensor adapted to detect the movement of the sensor arm and to generate an analogue signal varying in relation to the movement of the sensor arm, and in that the system comprises further a sensor arm pivotally mounted at a pivot point at a given location relative the inflation nozzle, the sensor arm having a contact portion, the sensor arm adapted to pivot on the pivot point as the terminal ends of the transverse seals of the web contact the contact portion of the sensor arm; the system being characterised in that the tracking sensor comprises an analogue sensor adapted to detect the movement of the sensor arm and to generate an analogue signal varying in relation to the movement of the sensor arm, and in that the system comprises further a controller operative to receive the analogue signal and based on the analogue signal to send output to the actuator to adjust the position of the roll on the spool to maintain the transverse position of the web within a predetermined range.