So according to another
thread here:-
Tailplane Icing
tail icing/rear stabiliser stall was to blame?
From what little CVR info released here....
PIO?
Buffetting and heavy stick pressure?
All seems to add up.
FO doesn't understand symptoms, does exact opposite of what is required, thinks it's a wing stall, has very little time to do anything about it,
Autopilot already took away all the early clues, and by the time he works out it's going bad...
..guess what
the aircraft goes into a steep dive at too low altitude for any form of recovery.
(In these cases it's always the cockpit hits the ground first).
It's very possible the wings looked clear of ice on the ground, leading to this false sense of security.
Maybe:-
Tail icing wasn't even brought into the equation.
Eg.-
"Investigators have said the Colgan Air aircraft seemed to be flying okay to the moment that the pilots lowered the wing flaps in preparation for final approach as the airplane dropped below 2,000 feet. In short order, the autopilot disengaged, the airplane's nose pitched downward, then upward, before a final pitch downward.
The aircraft rolled left, rolled right, dove sharply and hit the ground, in short order.
The NASA Lewis video cites four warning signs of ice build-up on the horizontal stabilizer: a lightening of the controls, particularly stick lightening in forward direction; a difficulty trimming the airplane; the onset of pilot-induced oscillation; and buffeting felt in the controls, but not the airframe.
"Individual pilots may perceive these warning signs at different times depending upon the pilot's experience, the icing conditions, the workload in the cockpit and the intensity of the situation. Now, it should be noted that if you are flying on autopilot you would almost certainly miss these symptoms because you would not get any tactile feedback from the controls."
The Colgan pilots were operating on autopilot until the autopilot disengaged.
Said NASA:
"Remember, many times, these symptoms are encountered when flaps are at full extension. In extreme cases there may be a sudden pulse forward stick movement, possibly very strong. The nose of the aircraft may sudden pitch down, and it is very possible that this may not be recoverable on final approach because of the low altitude of the aircraft."
Tail-plane stall caused by icing often is first noticed when the pilot increases the flaps, the power or the speed, NASA said. In the Buffalo crash, investigators said the pilots had increased the flaps. When it began going out of control, the Colgan pilots increased the airplane engines on full throttle.
On a normal wing stall, pilots usually should increase power and relax back pressure on the yoke or push the yoke forward. On a tail-plane stall, they should pull back on the yoke, return the flaps to their former position and, depending on the aircraft type, ease off on power.
In other words, the remedy for a wing stall in some cases is the opposite of the remedy for a tail-plane stall, NASA warned."
Also:-
The Real Reason Behind Regional TurboProp Icing Crashes
Who maintain:-
The ATR was designed and manufactured in France by Aerospatiale. Mr. Fredrick's book, Unheeded Warning, reveals how political considerations overruled the safety mandate that is supposed to govern the FAA's design certification decisions on aircraft of foreign manufacture.
Fredrick details strong evidence that some experts in the FAA, knew the plane would be dangerous in icing conditions, but they were overruled by higher officials because the French might have been offended if certification was denied by the FAA.
He also demonstrates that numerous "close-call" incidents and one accident (10-15-87, near Lake Como, Italy with no survivors), which preceded the Roselawn crash, were known to be the result of in-flight icing, but Aerospatiale effectively covered-up and did not circulate that information, lest the reputation of its ATR aircraft be damaged.