I intended to indicate that at 10000’ your blood saturation level is already below the level deemed necessary for 100% normal functioning. Yes it impacts everyone differently, and those that live at higher altitudes will have a better tolerance up to a certain point.

 

I don't doubt the physiological evidence, or that the level is below 100% functioning, just the amount it affects people. Below normal funcitoning is not a binary situation. Functioning at 10,000 ft will be better than at 14,000 ft for example. BTW, I'm by no means accustomed to 10,000 ft altitude, but when I have experienced it I didn't notice any significant effect. I realise it's subjective and I may have over-estimated my ability. However I would suggest that at 10,000 ft cabin the crew should have still been physically capable of taking the correct action. The unlikely assumption that it was a TO config warning was a terrible distraction which lead to delay in dealing with the real problem. By that time the cabin altitude would have been much higher than 10,000 ft and decision making would have become progressively more difficult.

 

Training should kick in when an aural warning like this occurs. I'm well aware there were previous instances of such confusion, but no competent 737 crew (or 707, 727 and 747 Classic crew for that matter) should ever be confused as to the cause of the intermittent horn going off in flight. The additional lights aren't necessary, but they do add to situational awareness and will prevent another crew making such a basic mistake. They haven't been mandated in the 747-200 for example, yet the problem there is exactly the same.

 

 

My statement was also directly in relation to this context which is a 737 in a climb and usually well above 10000’ when the cabin altitude warning goes off.

 

With respect, the aircraft altitude that the horn goes off at is irrelevant. The relevant altitude, in terms of oxygen levels, is that of the cabin. That was the altitude I meant throughout.

 

 

The first response should always O2 masks on and a descent, then any further troubleshooting as required.

Agree 100%

There Always more to learn.............

 

 

Paolo