Have operators really thought through what the SOPs mean; how should procedures be interpreted and actually carried out?
Henry VIII, not aiming this at you specifically, but post #2 provides several examples, which also appear elsewhere:-
Exactly what ‘unambiguous’ malfunction or condition will enable the crew to judge that the aircraft will not fly safely – and how do you judge ‘safely’? This might appear pedantic, but if we are not able to answer these aspects before the event then many opportunities for error could occur in ‘real event’ situations.
IMHO crews will not be able to determine the aircraft’s ability to fly until rotate (after V1). Humans might perceive that a ‘bang’ is bomb-related structural damage and not an engine stall, or that vibration from a flailing tyre is aerodynamic stall. Unless we have experience these events, trained for them or thought carefully about each situation, we all remain at risk from our ideas, preconceptions, and biases.
Whilst Red level warnings are usually unambiguous (lamp and sound), conditional Amber warnings may require additional assessment – perception and comprehension. How long does this take; possibly 2-4 secs and then another 1-2 sec to react. Pilots must have initiated the first stopping actions at or before V1, not just having thought about them (CS 25.107). What speed range does 5-6 secs of acceleration time represent?
IIRC aircraft certification requires that any failure resulting in inability to fly must be warned at the red level, thus critical systems are duplicated to avoid ‘hazardous failures’. Why should any amber warnings have to be considered at high speed?
What is a ‘sudden’ loss of thrust vs a ‘less than sudden loss’? This may be playing with words, but it indicates the need to define acceptable limits. Some aircraft can tolerate a reduction of 2% N1, others perhaps more critical, cannot. Thus it is necessary to provide guidance of what an engine failure is and how it is determined – some operators require a change in two engine related parameters or specific values. Similarly what is ‘severe’ damage? Again this is a judgement call, but without guidance and forethought there are many opportunities for error during a critical stage of flight.
In an airmanship model, judgement depends on awareness and knowledge, it requires currency both in thought and action, and as a foundation, discipline, again in thought and action. There is not much time for ‘thinking’ during a take off acceleration, thus we should make every effort to ‘know before we go’, but of course not prejudging events, yet remaining ‘go’ minded.
SOPs should reflect the points above and provide guidance for crews, if they don’t then crews must identify the problems to management – management initiate procedures, but the SOPs must ‘belong’ to the crew who are accountable for the action.
As an industry we need to think at lot more about our procedures, why they are written and how they can or might be followed.