Airbus noted in the appendix of the Taipei-Sungshan-Report something to the effect that to give accurate thrust figures, N1 would be required, which was not recorded.
Some posts ago someone posted a graph (I think it was our friend that fixes planes) that converts EPR in IAE engines to "corrected" N1 Values (N1/ROT2 ?). I saved it.
I searched a little bit and found something about EPR and ETR being key to find actual thrust. But it demands some calculation.
Why isn't it recorded in the FDR ? How do pilots know (if they know) what is the actual thrust they get from the engines ?