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Accelerated Stalls

A stall is an angle of attack, not an airspeed. The accelerated stall is the maneuver that proves it — a wing that quits with the nose near the horizon and plenty of speed on the dial.

Slow Flight, Stalls and Spins — FI.X.E

Why you practice it

Every stall you fly in training is one you set up on purpose, at altitude, with the recovery planned before you start. That is what the exercise is for: learning to see a stall coming, learning to keep the airplane out of one, and learning to get out cleanly if you end up in one anyway. Recognition, avoidance, recovery — avoidance being the part that keeps you alive outside the practice area.

This one is flown with a qualified flight instructor aboard. The accelerated stall breaks more sharply than the power-on and power-off stalls you learned first, it is the stall most likely to drop a wing and depart into a spin, and the entry loads the airplane while it does. Read what follows as preparation for a lesson, not as a procedure to take up and try alone.

The maneuver exists to break a habit the airspeed indicator teaches you. After enough hours of slow, nose-high stalls, it is easy to file the stall away as something that happens quietly, with the needle low. It does not. A wing stalls when it exceeds its critical angle of attack, and it can be made to do that at any airspeed, any attitude, and any power setting. This maneuver shows you a stall that arrives well above the stall speed printed in your POH, with the nose near the horizon and the engine still making noise.

The places this actually happens are not abstract. A steep turn flown with too much back pressure. A go-around where you pull hard to arrest a sink. Most of all, the base-to-final turn — overshooting the extended centerline, tightening the turn, hauling the nose around close to the ground. That last one is the classic loss-of-control accident. It is usually characterized as a cross-controlled stall, the airplane skidding with bottom rudder in, and a nose-high overshoot recovery can stall at close to one g without much load factor at all. What the accelerated stall teaches you is the other half of that turn: what the back pressure alone is doing to the wing.

What load factor does to your stall speed

In a level turn the wing has to do two jobs: hold the airplane up and pull it around the corner. Getting both out of one wing means producing more total lift, and you produce it by increasing angle of attack. That extra lift is felt as load factor — the airplane effectively weighs more.

Stall speed increases with the square root of load factor. At a 45-degree bank in level flight the load factor is about 1.4 g, so the stall speed goes up by roughly twenty percent. Steepen the bank and the curve gets unkind quickly: the load factor climbs much faster than the bank angle does.

Bank is only one way to load the wing. Any abrupt pull loads it — a sharp recovery from a dive, a hard pull-up, a gust or wind shear that changes the relative wind the wing sees. Weight, a forward center of gravity, and wing contamination raise the stall speed too. The wing does not care where the load came from, and some of it does not come from you at all. It only knows its angle of attack.

This is where maneuvering speed earns its keep, and it is worth being precise about what it promises. At or below Va for the airplane's current weight, full deflection of a single flight control will not overstress the airframe — the wing stalls before the structure gives. That is a narrower guarantee than it sounds. Va does not cover several controls moved at once, it does not cover a control deflected one way and then reversed, and it does not cover turbulence beyond the gust loads the airplane was certificated to. Va also drops as weight drops, so use the number your POH gives you for the weight you are flying that day.

Flying it

Start with the POH, because the POH governs the entry. Some publish a recommended entry speed for this maneuver. Some restrict or prohibit it in certain configurations — flaps extended, at gross weight, at an aft center of gravity. Check before the airplane moves, and where the book is silent, your instructor sets the entry.

Then a clearing check, and an entry altitude that leaves you recovering no lower than 3,000 feet AGL, in the configuration your instructor or evaluator specifies. Set the power so the airspeed stays at or below Va — fast enough that the stall is genuinely accelerated, slow enough that you are inside the structural margin. Pick a visual reference and a heading before you roll.

1. Roll smoothly into a coordinated 45-degree banked turn.
2. Increase back pressure smoothly and steadily. Not a jerk — a firm, continuous pull that raises the angle of attack while you hold the bank.
3. Keep the ball centered the whole way. This is the part that matters most.
4. At the first indication of the stall, recover.

Recovery is the same recovery it always is, and the order is not negotiable. Reduce the angle of attack first by releasing the back pressure and lowering the nose. Then roll the wings level with coordinated aileron and rudder. Then add thrust as needed — and needed is the operative word, because you entered this one powered and above stall speed, so it is usually a trim of the throttle rather than a handful of it. Return to your entry altitude, heading, and airspeed at the climb speed your POH publishes.

How much altitude that costs depends on the airplane and on how late you caught it. An accelerated stall breaks abruptly, a wing drop is common, and a recovery that starts a beat behind the break costs more height than a prompt one. Give yourself more room than you expect to use, and watch the airspeed on the way out — lowering the nose from an entry that was already fast builds speed quickly.

Recognizing it

The reliable cues are the stall warning horn and airframe buffet. Nearly everything else you have learned to associate with an approaching stall is missing here. The airspeed is not low. The nose is not high. The engine is not quiet. And the controls do not go soft: at these speeds the aerodynamic pressures stay firm right up to the break, so the mushy, unresponsive feel you were taught to read as a warning never arrives. The buffet, when it comes, comes sharply and with little notice, and a wing is more likely to drop with it.

So the emphasis shifts to the horn, the buffet, and your own awareness that you are deliberately loading the wing — not to the picture out the window, not to the feel of the controls, and not to the airspeed indicator. Recovering at the first indication means the first one you get, not the one you were expecting.

What goes wrong

The most common error is not stalling at all. If the pull is timid, you have flown a steep turn and called it a maneuver.

The opposite error is entering too fast and exceeding Va, which trades a stall for a structural problem. Between those two sit the errors that carry the real risk: uncoordinated control inputs while the wing is near the stall, which is the recipe for a spin entry rather than a stall, and which is why there is an instructor in the airplane and 3,000 feet underneath it; delayed recognition, because the cues did not look familiar; and pulling back too soon in the recovery, before the angle of attack has actually come down, which gives you a secondary stall lower and slower than the first. Recovering from a secondary stall, like the spin it can lead to, is instructor-taught territory in its own right.

The instinct to protect altitude is what causes that last one, and it is worth naming out loud. Close to the ground, lowering the nose feels wrong. It is still the only thing that breaks the stall.

Where you meet it next

This is a commercial and flight instructor task, and the standards it is graded against are specific: a coordinated 45-degree bank, entry at or below Va, recovery at the first indication of the stall, and completion no lower than 3,000 feet AGL, with a return to your entry altitude, heading, and airspeed.

It is also the bridge between lessons you have already flown and ones still ahead. The 45-degree bank is the same bank you hold in steep turns — the accelerated stall is what waits on the far side of that back pressure if you keep adding it. The power-on and power-off stalls gave you the cue set this maneuver deliberately takes away. And it points forward to the cross-control stall and to spin awareness and recovery, both of them demonstrated by an instructor: load the wing in a turn while uncoordinated, low and slow, and the stall becomes a spin with no altitude to trade for a recovery. Everything you drill at 3,000 feet exists for that one turn in the pattern. The rest of the ground school library works the same aerodynamics from the other directions.