The basic problem is clear. During an engine failure on a twin wing-mounted engine aircraft there is an assymetry between the left and right sides – that is, typically one of the engines is producing lots and lots of thrust; the other is producing none at all (and in fact may well be producing extra drag with windmilling fan blades, etc). A pilot therefore needs to counter the quite strong tendency of the aircraft to yaw towards the failed engine or else lose control of the aircraft altogether. Sufficient rudder pedal input on the flight deck is required to deflect the rudder on the tail to offset the asymmetry. A badly handled engine failure can result in poor climb performance – or none at all. The loss of an engine in today’s big twins typically results in a loss of 50% of available thrust – and over 80% of available performance.