Originally Posted by Best foot forward
... shouldn't be used to formulate a policy is sheer folly.
Rare events such as Manchester may shape SOPs, but they should not ‘dictate’ policy and in doing so overlook more probable scenarios. One of the major sources of error is that crews/operators fail to correctly define the problem – failure to assess the relative risk, thus SOPs could be focussed on the wrong problem – they might provide inappropriate emphasis which could bias a crew in their decision making. This is typical of concentrating on the latest or the ‘brightest’ accident without understanding the relative risks. (
Errors in Aviation Decision Making.)
In addition we should not forget the ‘unforeseeable’ events which constitute the majority of accidents – you don’t have the same accident twice (situations), but there are ‘no new accidents’ (same contributions – including human error), thus it is essential to look for the warning signs; in this case ambiguities or conflictions in SOPs.
Ever since power plants have had fire detection there has been the dilemma about false warnings. The reliability of modern warning systems is much better than those of even a decade ago, thus where human judgement was required for confirmation, nowadays most warning systems can be taken as correct, particularly as the probability of a false fire warning is less than the probability of a human misjudging the situation i.e. we can cut one option out of the decision making process. We often fail to appreciate these improvements in our SOPs (SOP revisions).
This could be a hint for automatic evacuation for a fire, but I would balance this with improved fire containment, better extinguishers, and lower engine failure rate – thus the lowest risk might still be with the crew assessing the scene after the stop – the warning system is only one cue – take a look, get other advice, but for the obvious situations then there is no delay - evacuate.
These technological improvements have taken place in many systems and therefore might apply to many SOPs and decision scenarios; although this concept still does not provide absolute safety, the level of safety achieved (achievable) today is better than in those situations where a greater range of judgments were required.
The industry must not forget accidents such as Manchester, but we have to acknowledge the many improvements since then and look ahead for other, as yet unidentified threats.
Slightly off topic; who retains a ‘conditional’ statement in their EGPWS Pull Up SOP? i.e. “if visual with … etc”. Is this a hangover from the old GPWS; is the conditional evaluation (decision) still warranted with the modern highly reliable terrain displays – with significantly lower nuisance rates than pervious equipment? Mounting evidence suggest that crews encountering TAWS warnings due to error, perpetuate the error with their conditional evaluations – some failing to pull up in hazardous situations.
A subject for a new thread ? - Mod BOAC please consider.
P.S.
Bff, in your freighter do you turn as you stop from a RTO – for interest, why/why not?