Originally Posted by
CL300
Actually it is 15° flaps max in icing. and 160 kt MIN , in very icing conditions, with a T-Tail and the Austrian maintenance.. I would not dare to extend any flaps in severe icing.
But it is only me...
Flying in ice can be tricky. Myself experienced 2 similar like a stall in a C421, both at 130 KIAS. One was without height loss but the attitude was oscillating. The second it started to descend by its own. During my type rating for EMB120 they showed us printouts from icing incidents. One did 12 turns in spin, then recovered, another turned while intercepted loc to the wrong side. But all showed the same characteristics, first oscillating in attitude, then the full stall, at 154 KIAS. The reason seems based on laminar profile, are sensitive to a contaminated upper surface, which lengths seem to change and so created the onset/oscillation.
If I have a to do an approach in ice, first I check the ceiling. If it is above outer marker check altitude, I delay flap extension until outer marker. Often wings went clear if reaching freezing level. But such a high-speed approach has to be flown before and the crew has to be sure to have it stabilized. Even a landing with approach flaps has a different feeling and has longer runway requirements, esp. normally RWY is contaminated or wet.
In this accident selecting flaps could trigger tail stall. Maybe there was a condition as the crew selected flaps because the moment of wings is increased with flaps at same speed. If the horizontal stabilizer was near the max alpha, it could stall, what leads to loss of control. A tail stall occurs at higher speeds than a wing stall and masks flaps asymmetry. But only official docs will give further proofs. We are just talking about general considerations of flying in ice. VLJ has many limitations. Sometimes I wonder, how can such a small jet carry so many limitations. If want to use the full envelope, it is desired to develop some kind of personnel trainings programm.