Originally Posted by
tdracer
That may sound great in theory, but in practice it's nearly impossible to implement. Engine failure at V1 must be controllable, and it's demonstrated during cert. But there is a certain probability that a sub-par pilot will botch it when it happens to them in real life. Does that mean we can't certify unless we somehow 100% eliminate the possibility of a V1 engine failure? Better ground the worldwide fleet because no one knows how to do that.
How do you quantify 'controllable' with hard and fast 'ruler' requirements? Hence the requirements are sprinkled with terms like 'unusual pilot skill'. We try to design for the lesser skilled pilots, but you need to draw the line somewhere or we'll never be able to certify a piloted aircraft.
I agree, it's not 100% avoidable to have some vagueness, in the end, flying is (for the foreseeable time) a human driven process.
However, striving to minimize the amount of vagueness could be very useful.
Engine failure at V1 controllable can be specified in maximum flight-path/3D-position/energy deviations vs. time, given a maximum amount/reaction-time of control input.
Compare this with EGPWS. EGPWS effectively creates a dynamic multidimensional "virtual-path", where it is safe to fly. As long as the aircraft stays within these multidimensional boundaries, the aircraft is safe. Move outside this virtual-path and the dangers start adding up, sometimes very quickly.
For the V1 failures, a similar virtual-path can be defined and used as a certification requirement. Define the maximum amount of correction required, vs. the reaction time, and things do get quite deterministic. This would immediately wipe out the possibility that an outright dangerous aircraft will pass the certification tests (because with the vague certification criteria, an ace could save the aircraft certification). This way, you create "a ruler" to be used for the certification. When the current certification criteria were established, technology wasn't available to specify and/or measure this type of specifications, so, one did water down these certification criteria to "average pilot", etc. Nowadays, math, computational power as well as sensor capabilities are an order of magnitude better and a different, less vague, approach to certification would be feasible.
And, because the aircraft certification gets deterministic, the pilot certification can also become more deterministic. Still not perfect, though getting better than the vague "average" qualification.