DALLAS, Texas — It is a daunting task, even for a highly trained firefighter or police officer. 

Each year, tens of thousands of people from around the world climb 110 flights of stairs to honor the 343 firefighters who died.

According to the Dallas 911 Memorial Stair Climb website, stair climbs date back to 2004. Traditionally, first responders carry their gear during their climb to simulate the struggles of their New York City Fire Department brethren on Sept. 11, 2001.

The Henderson County Sheriff's Office announced Tuesday Officer Casey participated in the Dallas 911 Memorial Stair Climb on Saturday at the Renaissance Tower.

This is the second year Casey has participated in the climb.

The event is meticulously planned to match the timeline of the tragic events of 9/11.

At 8:46 a.m., the exact time the first plane hit the North Tower of the World Trade Center, there was a moment of silence to honor the heroes of that day.

At 8:47 a.m., the climbers began their ascent. Another moment of silence was observed at 9:03 a.m. to mark when the South Tower was hit.

Moments of silence were also be held at:

  • 9:37 a.m. to mark when the Pentagon was hit
  • 9:59 a.m. to mark the collapse of the South Tower
  • 10:03 a.m. to mark the crash of Flight 93 in Shanksville, PA
  • 10:28 a.m. to mark the collapse of the North Tower

This was the ninth year the City of Dallas has hosted a 9/11 climb.