Originally posted by Gabriel
View Post
I think one thing that is confusing me is that these procedures were never written or intended for the sudden and total loss of airspeed data (i.e. ice ingestion) and autoflight in the cruise-level phase of flight, as the phenomena of supercooled water and high elevation of ice crystals was not well-understood and therefore that was previously not considered a plausible (or even possible) scenario. So memory (instant recall) items do not exist for this scenario.
So, the memory procedures, which yield a climbing flight path, do not apply to cruise-level flight unless "the safe conduct of the flight is affected" (I assume this means wherever a climb is necessary), but the QRH procedure still calls for, as a first action after shutting down the AT and FD's, factory-engineered pitch and power settings. As I said in my previous post, I'm fine with that. My concern has always been that pilots avoid improvising on pitch and power, even if they consider it "known" to them, and that the initial commands departing from the current flight path are guided by these reference values.
There are problems with that though. For one thing, the total loss of speeds in high-altitude turbulence results in an immediate loss of autoflight and need for manual intervention before the QRH values can be obtained. The pitch attitude prior to the disconnect could be quickly lost in that choppy, rolling transition. Therefore, it seems logical that a similar pair of broad, cruise-level-flight pitch/power targets should also be provided as a Memory Item for all weight categories above and below FL250, just to stabilize within the safe envelope for a minute or so. Again, I agree that a provisional autoflight mode is the most optimum idea and I don't see any reason that it can't, or shouldn't, be implemented.
In any case, I remain steadfastly opposed to the idea of improvisation here. That has to stop. WIth no speed reference, misleading altitude and vertical speed references and the FD in self-destruct mode and the autothrottle in stealth mode, the procedures and engineering-derived pitch and power targets must be expediently followed.
Comment