Originally Posted by
infrequentflyer789
Yup. From that same data source (and wishing vbulletin did tables):
737 NG: >20 years, >7000 built*, 20 hull losses, 591 dead
737 MAX: <3 years, ~350 built, 2 hull losses, 346 dead
So, if it's the crews or the airlines and not a problem with the plane, how do you explain the (order of magnitude at least) difference in crash rate?
On the surface that is an interesting observation, however it is the result of working with unequal population sizes and looking at temporal processes. Safety of a system is judged by exceptional events, losses in aviation. overall, historically loss rate has loosely followed a curve similar to long term average costs in economics, a broad U shape. initially there is a potential elevated risk from unknowns in a new system (airline, aircraft, route, operation etc..) which is mitigated by the control loop of the system. After an extended period of time new factors will come into play, which may elevate risk, loss of corporate knowledge, structural fatigue, ageing effects, apathy etc. these are also affected by the overall system response which should improve over time, and it does to an extent, SSID, SMS etc, but the underlying issues are non linear, and the system response is also non linear. Responses hardly ever are exactly correct and without new risks and unintended consequences.
Pretty much, systems are non linear. Estimates based on largely different samples are only correct in say QA sampling, and even then it comes with interesting maths due to uncertainties.
The NG didn't make headlines on safety with its introduction, however there were considerable fatalities from the start for various issues, and the fatality rate then reduced. The losses occurred in the noise of other events, and did not raise eyebrows. in more recent time, we continue to see over runs, loss of control, and similar crew related matters increase on the NG. The A320 started with a lousy run of losses, most due to knowledge issues with the crew related to the automation functions. the A320 loss rate continued to be managed, but there are still wild card events that occur to this day, including loss of control, CFIT and other odd events.
Both of the airlines involved with the most recent events have considerable track records with accidents, all of them raising questions on system integrity. For the regions that they operate in, at least in Africa, ET is one of the better performers. In Indonesia, safety records are always of concern, and JT has had its share of events and losses, which given its size of operation is probably not far from the average in the country. Indonesia like Africa has elevated operational risk factors, that even if comparative operational standards exist would probably lead to more incidents of the type that are most common there, overruns and offs of the runway. Loss of control events have occurred with various aircraft types in the region, for a multitude of reasons, crew turning off the attitude platforms, severe weather encounters...
The question on the Max is why did apparently trained crew not recognise and action a simple procedure in the events. Stab cut out has been fitted since the 40's, when stabs were the solution to high speed flight trim changes. Cutout is not a new device, nor is the problem of uncommanded stabiliser trim changes. So with the Max, what is the reason the crew didn't recognise the need to do a simple action to save the day? The concurrent stall warning would appear to have had a strong influence on the cognitive capabilities of the crew on the day. The revised event information of the JT aircrafts prior flight suggest that on the day that crew also needed additional input to successfully undertake corrective action. The CVR info on JT610 starts to suggest that the crew did attempt to manage the event in a calm manner, but with that process, the hand over of the flying duties from the capt to the copilot had a down side, the captain had been responding to the uncommanded trim, the copilot was not successful in doing the same and the flight path was promptly affected. It is indeed unfortunate that the captain following CRM best practice training principles takes action that appears to have had severe consequences. If the captain had recognised the trim problem consciously, cutout would have been an appropriate action. The copilot was handed an aircraft with the problem, and it is quite possible (unknown at the moment) that the captains successful reactions to the trim problem were subconscious, and that it was being managed so was not communicated at the time of the transfer to the copilot. That point is going to need consideration for any real longterm improvement in problem cueing, where the comprehension of the crew of the actual status is critical. Crew SA is paramount, and what appears to be 3 cases so far had problems in this area.
I don't think that these operators are unique in the issue of SA at all.