But if you are not up to scratch with a manual GA on instruments in IMC, especially if you are slow to operate the stab trim in conjunction with forward elevator to ease the stick forces as the pitch up occurs, then the pitch angle can quickly increase to a dangerous angle.
What I should have added to the highlight above (but I forgot) is that even if the pitch up is getting out of control due to slow reaction by the pilot, the Boeing advice is to:
"If normal pitch control inputs do not stop an increasing pitch rate, rolling the airplane to a bank angle that starts the nose down should work. Bank angles of about 45 degrees, up to a maximum of 60 degrees could be needed. Unloading the wing by maintaining continuous nose-down elevator pressure keeps the wing angle of attack as low as possible making the normal controls as effective as possible.
With airspeed as low as stick shaker onset, normal roll controls - up to full deflection of ailerons and spoilers - may be used. The rolling maneuver changes the pitch rate into a turning maneuver, allowing the pitch to decrease. Finally, if normal pitch control then roll control is ineffective, careful rudder input in the direction of the desired roll may be required to induce a rolling maneuver. for recovery.
Only a small amount of rudder is needed. Too much rudder applied too quickly or held too long may result in loss of lateral and directional control. Because of the low energy condition, pilots should exercise caution when applying rudder. The reduced pitch attitude allows airspeed to increase, thereby improving elevator and aileron effectiveness. After the pitch attitude and airspeed return to the desired range the pilot can reduce angle of bank with normal lateral flight controls and return the airplane to normal flight". Unquote
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That advice is gold standard and should be learned by heart for all pilots as it applies in general to most types of aircraft from Cessna 150 to Boeing 737.
Because of the relative complexity of this recovery action from high pitch angles, it is should be practiced regularly in the simulator under simulated IMC. That is because when unusual attitude situations occur such as those described above, it is most likely at night or in IMC.
From the above, and that includes the Boeing FCTM advice, it is easy to understand the vital importance for pilots to maintain their basic instrument flying skills on raw data.