470 kts is a known engineering constraint. The FCS is certified to 333 kts. However, a Loss of Control (LOC) will probably not occur unless the EAS is in excess of 470 kts, which will lead to an LOC due to over-gained and under-damped FCS gains. 2007 February 14, NASA, “1.4.2 Black Zones”, in Contingency Aborts 21007/31007, archived from the original on 26 Feb 2021, page 13:
(abbreviation, alt-of, initialism) Initialism of East Asia Summit.
(US, abbreviation, alt-of, initialism) Initialism of Emergency Alert System a public warning system that receives alerts from NWS, NOAA and other government and civil defense agencies and transmitted it to the general public through television and radio stations.