The Willis Tower – formerly the Sears Tower – has long been a popular tourist attraction, chiefly for its observation deck, where visitors can catch a stunning view of the Chicago skyline 103 stories off the ground. At that height, you can watch helicopters and planes fly by at eye level, and the drop to the pavement looks like it would take about a full 30 seconds, were one to be so unfortunate as to test the theory.

Sensing visitors' competing impulse to both go to the top of the building and to not fall all the way back down, in 2009 the tower installed its famous SkyDecks: plexiglas observation boxes that jut out from the plane of the skyscraper itself so that one can walk out and, essentially, stand suspended in mid-air high, high, oh-so-very-high above the rest of the city. When my family visited Chicago last summer, naturally, I was keen to go out on it. My wife, who has a much stronger sense of risk management than I do, was hesitant, but being a good sport, she went out anyway. The entire Coffin family stood just a few sturdy inches from sure oblivion all in the name of a nice group shot and a few selfies.

Of course, my wife is having the last laugh, as news spread today of an apparent shattering incident in one of the SkyBoxes. According to NBC5 Chicago and the Chicago Tribune, a family from California was in one of the boxes when they heard a crackling noise. Apparently, a protective coating on the deck floor crackled – which is engineering talk for when something breaks in a specifically designed way as to distribute stress. The family got out of the deck (bravo) and took photos and video until they were asked to leave.