Peter Dohm wrote:

We really don't know whether they actually had tailplane ice at the time,
not whether they did not, and we never will know because that sort of
evidence would not reasonably survive a crash.

Knowledgeable people (as eg. NTSB's accident investigators) tend to read
a lot out of the FDR data. I'm pretty sure we *will* know when the final
accident report is released.