Operationally its irrlevant because the FAA limits speed
below 10K ft to 250Kts IIRC.

And Mohamed Atta conveniently ignored this rule. The 9/11 planes went so
fast and so low that they were expected to fall apart in-flight. Boeing
made them too sturdy, however. I wonder if some legal-savvy widows will
sue Boeing for building too good planes and thus causing 2800+ deaths.