aterpster :
Thanks for the historical. . Learn something today! .
On the windshield /bird strike certification I remember during my training of a requirement that said aircraft windshields needed to be able to withstand a strike with a bird of a certain mass atthe maximum approach speed.because 99% of birds are found below 10.000 ft. and a very high percentage ( something in the region of 80-85% ) of actual bird strikes occur in departure and approaches phases.
I seem to remember both criteria were taken together to make a single rule below FL100. of a standard max speed acceptable for jets of the time i.e 250 Kts .
There was a proviso that certain aircraft types (i.e. military) could be exempted. That was long time ago. Maybe someone with better memory or wanting to dig into old books or internet can confirm or correct.