Firefighters wear a motion-sensitive alarm which will go off if the firefighter remains motionless for approximately sixty seconds. This alarm can summon help when a firefighter can't. Called a Personal Alert Safety System (PASS) device, firefighters can also manually activate it if they need help. PASS devices can be heard in much of the videos shot at Ground Zero immediately after the building collapses.  

Firefighters climbing in the stairwell at our event will activate their PASS devices at the exact moments in time that the towers collapsed: 9:59 and 10:28am. After activated, climbers stop climbing and listen as Taps is played both inside and outside the building. A moment of silence is observed before climbing continues.