" 
 A further question. We know that a/c fly by wire. The Concorde had an analogue signal modifier to give good flight handling. From inception Airbus had flight envelope limitation ""to stop the pilot making a mistake, although the pilot can turn it off"". Comment  the Indian crash was blamed on pilot error. Presumedly all modern passenger a/c have a digital computer between the pilot and the control surfaces. The issue is can the pilot switch all the digital systems off, or to fly must control still pass through a computer ? In anticipation, thanks."