Originally Posted by
lomapaseo
Predicted IFSD rates are not expected to rise because of ash ingestion as it would only be an minute contribution among all the various causes.
They may not be
expected to rise - but aren't ETOPS certifications based on documented actual IFSD rates achieved by certain operators under standard conditions? It remains to be seen whether rates will change after fleets have spent a week or two operating in the ash environment.
Originally Posted by
lomapaseo
Futhermore ETOPS is predicated on independendant en-route failures and not on common cause which affects more than twin engine aircraft.
Indeed - but the point I was trying to make was that if operating engines in an ash environment for a period of weeks compromises future reliability - then the probability of two independent en-route failures during future ETOPS is increased.
Let me put it this way - this summer you have an IFSD during ETOPS. How comfortable will you be with the fact that your one remaining engine spent a week or two operating in an ash environment?