False-18.104.22.168 - jammers are considered in position and ready if they are entirely in bounds when the jam-starting whistle is blown. jammers are subject to false start penalties if they are not on or behind the jammer start line at the jam-starting whistle (see section 6.13.22 for specific penalty details). jammers are permitted to put on their helmet covers after the jam has started. however, each jammer must have their helmet cover on their head or in hand before the jam-starting whistle. a helmet cover cannot enter a jam in progress.