we too ran this risk unknowingly

 

 Glass Cracks Below Tourists in Chicago Skydeck

Participants stand on the new glass balconies suspended 1,353 feet in the air and jut out 4 feet from the Willis Tower's 103rd floor Skydeck on July 1, 2009 in Chicago.

Image: Kiichiro Sato/Associated Press

By Jessica PlautzMay 29, 2014

In what could have been a nightmare come true, part of the glass floor in a viewing box high above Chicago cracked right below a group of California tourists. But it was apparently much less of a problem than it might have seemed.
Alejandro Garibay and his family were taking in the sights at Chicago's Willis Tower on Wednesday night. The tower's Skydeck, which opened in 2009, is on the 103rd floor, about 1,353 feet above Chicago's downtown.

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Right before stepping on the glass, Garibay and his family were joking with Willis Tower staff about the safety and durability of the glass.
"They jokingly and confidently responded, 'It's unbreakable,' so we just went on," Garibay told the NBC affiliate station in Chicago.
While on the glass, Garibay heard cracking. He and his family told the staff, who directed them away from the glass box.

"When we pulled our phones to start recording and take pictures they asked us to leave right away," Garibay said.
A building spokesperson told the Chicago Sun-Times that it was the protective coating that cracked.
“Occasionally this happens, but that’s because we designed it this way,” he said. “Whatever happened last night is a result of the protective coating doing what it’s designed to."
The Skydeck, which provides panoramic views of the city, was open on Thursday.

A view down through the glass from one of the boxes in the Skydeck.

Image: Flickr, David Berkowitz

we too were there on the glass deck   in spinnaker tower  portsmouth  england .
thank god we did not hear any cracking sound. either of the glass or the protective 
coating. in either case we wound have fainted . all of us