Okie firefighters from the 507th Civil Engineer Squadron at Tinker Air Force Base, Okla., hike up the stairs of the fire training tower Sept. 11, 2016, during their 7th annual fire climb, held to honor the victims and heroes who perished on that day 15 years ago. Every year, Reservists climb up and down the fire-training tower to complete the 18 laps within 56 minutes, the amount of time it took the South Tower of the World Trade Center to collapse. (U.S. Air Force video/Tech. Sgt. Charles Taylor) More