Modern Elmo, by "real" speed change I meant the actual speed of the plane, not what was indicated.
I.E. - did the aircraft actually "sharply" lose 215 kts of TAS (or whatever 215 kts IAS equates to at that altitude, in TAS), or was that indicated "sharp" change an artifact of the icing of the pitot and/or other things - not including the "real" speed.
Sorry if I was unclear.