reply to post by slugger9787
I see you found the very article that I had read, and was searching online for last night, but had Internet connection problems. Yes, that Air Line
Pilot article form February, 2001 about the evaluation of the B-767-400 came to my mind, since it proves precisely my point.
Glad you linked it. Was that an admission that you now understand that it IS possible to descend at 5,500 fpm?? (In decades of flying, in many
different large jets, I routinely saw the VSI 'pegged' full down, at its max range of 6,000 fpm. That would be only for a few minutes,
however...obviously, because of the altitude changing...and also that, without drag ---- like the speed brakes ---- the airspeed increases rapidly.
Oh, wait...that's EXACTLY what the guy flying UAL 175 wanted!!!)
I see you truncated the discussion, so here is the rest:
To make this more interesting, and because it is standard procedure at some airlines, I flew the maneuver completely on the autopilot. I dialed
the altitude from FL290 down to 11,000 feet, disconnected autothrust and brought the throttles to idle, dialed the speed up to 350 knots, and deployed
On the initial pitchover, the rate of descent increased to 9,600 feet per minute at 7½ degrees nose down, then slowed to 5,300 feet per minute as the
airspeed stabilized at 353 knots. The time from start of the descent to level-off at 11,000 feet was just 3 minutes. Very impressive, particularly
since we flew the maneuver by interfacing with automation, rather than manually.
He is correct --- some airlines train to use the A/P. MY airline, we did it both ways, to accommodate different scenarios that would be possibly
encountered. Our training syllabus said that EITHER the manual, or the automated method was acceptable. Automation (if available...that is, IF you
also didn't have a total electrical failure at the same time, when conducting the Rapid Descent) was recommended because it would, when properly
programmed, level you off where desired (target was 10,000 feet...except when in mountainous terrain areas, where the MEA - Minimum Enroute Altitude -
at our location and route were higher).
Further, our checklist required to ascertain, prior to descent, whether we suspected any structural damage. IF damage was suspected, then we were
told to maintain the same airspeed, and not accelerate in the descent, as a precaution. Otherwise, it was "throw out the boards" (speedbrakes),
engines to idle, and pitch down to Vmo, either on A/P or manually.
Important to note, isn't it, that when WE do it, engines are at flight idle. NOT shoved up to full thrust.
BTW, note also the nose down 'deck angle' (pitch attitude) they saw at first....7 1/2 degrees. That's about right, especially since they had
speedbrakes deployed. Anyway, if you had been a passenger in the back, ~7 degrees nose down isn't substantial, you'd hardly notice.
Oh, and gee! (This belongs in another thread...where there are "claims" of "excessive" G-loads on United 175...)...obviously, leveling from such
a descent rate is a piece of cake, and DOES NOT exert excessive loads on the airframe....those guys in the Air Line Pilot magazine article didn't
break the airplane, after all.....