Kathy McGrade, graduated from the New Mexico Institute of Mining and Technology in 1979 with a earned a bachelor in metallurgical engineering degree. She spent the next 30 years with three startup companies, then founded her own company, Failsafe Testing, which she still runs today. Among her achievements in the field, she took a non-destructive testing technique called Acoustic Emission and applied it to fire service aerials to evaluate the structural integrity of their aerial ladders.
The symmetry is the smoking gun. It cannot happen that when you have asymmetric damage, you will get a perfectly symmetrical collapse.