Originally Posted by
vilas
Failure of anti skid causes down grading to CAT III single. Setting parking brake disconnects normal braking, may be no signal from anti skid causes this.
Having thought about this. The only braking failures that cause CAT 3 DUAL inop is NWS or anti skid fault.
Must be the BSCU detecting a false failure of one of those temporarily when you press the pedals.