Is a simple maneuver, we all did it at the beginning of our flight training. Basically there were two types, power on and power off stalls. Remember? Just keep the nose above the horizon with wings level, the stall horn will sound, lower the nose and…here we go again, we have speed and can continue flying, we can play this game all day.
What is not a game is the rising concern about the amount of accidents that happened because simply the pilots did not recognize or could not recover the airplane from a stall. There are many disturbing and recent examples, like the Air France 447, an Airbus 330, which had a high altitude stall and three pilots on the flight deck could not detect / recover the aircraft from the stall until it hits the water. Other example is Colgan Air 3407, a Bombardier DHC-8 Q400, which stalled on an ILS approach, the pilots did all the actions to try to recover the airplane from the stall, except…lower the nose, the captain keep pulling of the control yoke until hitting the ground. And the list continues…
What is happening to our aviation community?. Too much automation and we are forgetting how to recover an airplane from a non-normal condition?
Experts are concerned about this situation and some aspects are beginning to change. I remember couple of years ago when I was doing the initial to fly new equipment and when practicing stalls on the simulator the instructor told me: – at stick shaker, keep the attitude and add max power, don’t lower the nose. Also someone said: – not more than 100 ft altitude loss. At first this seemed unnatural and confusing to me, used until then to lower the nose and add max power. But at this point is exactly where we are failing, you can tell after read in deep on the above examples.
Seems like this is beginning to change now and after trying something that turned to be a serious problem we are reverting to the old school, a few days ago when participating of a training seminar, the instructors in class made a presentation, discussion about stall recovery and the suggestion was simple: “lower the nose, level the wings and add maximum power”.
What happens during a stall in a fixed wing aircraft is extremely simple, as the pilots increases the angle of attack the airfoil experiences a reduction on the coefficient of lift, the stall occurs when the critical angle of attack is exceeded. Most airplanes are equipped with devices that alert the pilot of the imminent stall, a simple horn in small general aviation airplanes and stick shakers in advanced airliners, these devices actuate before the onset of the actual stall, from there the reason we were told by instructors to keep the attitude at first sign of alert and add maximum power. But for some reason in some cases something went wrong with the remaining actions during the recovery and the airplane fully stalled.
There are dozens of articles and videos, some of them very good and explanatory about stall and stall recovery, so it is not my intention to go in a deep explanation about what happens on the onset and recovery of this maneuver, simply review another fact that attracts concern about recent incidents and accidents.
By Ivan Paredes
There’s also a good dramatization by Air Crash Investigation on both accidents: