How Flying Works
What a Stall Actually Is (It’s Not About Losing Power)
On approach to Buffalo on 12 February 2009, Colgan Air Flight 3407’s stick shaker went off. It’s a violent vibration built into the control column to warn that the wing is nearing its critical angle. The captain pulled back on the controls and added power, the instinctive reaction of someone trying to climb away from danger. It was exactly the wrong input. The aircraft, a Bombardier Q400 flown for Continental Connection, stalled and crashed into a house in Clarence Center, New York. All 49 people on board and one person on the ground were killed. The NTSB’s finding was direct: the probable cause was the captain’s wrong response to the stick shaker. To see why it was wrong, you need to know what a stall really is, and it has almost nothing to do with what most people assume.
It's an angle problem, not a power problem
A stall isn’t the engines cutting out, and it isn’t simply “flying too slowly”. It’s purely aerodynamic, and it’s defined by the angle of attack. That’s the angle between the wing and the oncoming air, not the angle between the aircraft and the horizon. Every wing has a critical angle of attack, usually about 15-18 degrees depending on its shape. Beyond it, the smooth airflow over the top of the wing breaks away into churning, messy air, and lift drops sharply. Go past that angle and a wing will stall at almost any speed. Stay under it and the wing keeps making lift however slowly the aircraft is flying. A glider with no engine can fly for hours without stalling, as long as its angle of attack stays below the limit. That’s the clearest proof that engine power was never the thing that mattered.
Try it
Angle-of-attack lab: tilt the wing, change the speed
Each dot is a bit of air. Tilt the wing and it pushes more air down behind it (the dots bend downward), and by Newton’s third law the air pushes the wing up. Lift also grows with the square of speed: twice as fast means four times the lift. That’s why slow aircraft need a bigger angle, and why there’s a limit: past about 15°, the air can no longer follow the curved top, it breaks away in swirls, and lift collapses. That’s a stall, and it’s about angle, not engine power.
The warning built specifically to stop this
A stall can be prevented right up until the critical angle is reached, so modern aircraft carry layers of warnings designed to act before it happens. A stick shaker shakes the control column as the aircraft nears the critical angle, a warning that’s impossible to miss. Some aircraft, including the Q400 that Colgan 3407 was flying, add another layer: a stick pusher. If the pilot doesn’t respond to the shaker in time, it pushes the control column forward automatically, cutting the angle of attack directly. The NTSB faulted the airline for not emphasising full-stall recovery and the pusher response in its training. That jolting, unfamiliar automatic input came during an already stressful approach, in icing conditions the crew had discussed shortly before. The NTSB found the captain pulled back against it.
Why the instinctive response is exactly backwards
Pulling back on the controls raises the nose, which increases the angle of attack. That takes the wing closer to its critical angle, not further from it. It feels like the natural response to a warning about lift, but it does the opposite of what recovery needs. The right response is to lower the nose to reduce the angle of attack so the air flows smoothly again, then add power to help. Every airline pilot drills it, because the instinctive reaction under pressure goes the wrong way. Colgan 3407 remains one of the clearest and most costly examples of that gap between instinct and correct technique. It helped drive changes to US airline training rules, including stall-recovery practice (the FAA’s 2013 training rule took effect for airlines from March 2019).
Why some jets need a pusher: the deep stall
Most airliners carry the horizontal tail low, at the back of the fuselage. Some, including many regional and business jets, mount it on top of the fin. That is a T-tail.
A T-tail keeps the tail clear of engine exhaust and the wing’s wake in normal flight. But at a very high angle of attack, the stalled wing throws a broad wake of turbulent air backwards and upwards. On a T-tail design, that wake can engulf the tailplane.
The elevator, the control the pilot uses to push the nose down, then sits in disturbed air and loses its power. An aircraft in this state, called a deep stall, may not be able to lower its nose to recover.
That is why aircraft prone to deep stall don’t stop at a stick shaker. They also have a stick pusher, which forces the controls forward just before the critical angle is reached, so the deep stall never starts. The rule of aerodynamics doesn’t change. The design adds a mechanical guard because the cost of crossing the line is higher.
Sources & Further Reading
Common Questions
Frequently Asked Questions
Can a plane stall with the engines running fine?
Yes, easily. A stall is about the angle between the wing and the oncoming air, not engine power. An aircraft with both engines at full thrust can still stall if the nose is pitched up too steeply. And a glider with no engine at all can fly for hours without stalling, as long as its angle of attack stays below the critical angle.
Does a stall mean the plane falls out of the sky?
It means the wing stops making enough lift at that angle. It doesn’t turn the aircraft into a brick. Recovery is a clear, heavily trained procedure: reduce the angle of attack, usually by lowering the nose, so the air flows smoothly over the wing again, and add power to help. Every airline pilot drills this in the simulator so the right response is automatic under pressure.
What is a stick shaker and a stick pusher?
A stick shaker shakes the control column as the aircraft nears its critical angle of attack. It’s a warning you can’t miss, felt before the stall itself. A stick pusher goes further: on some aircraft it automatically pushes the nose down if the pilot doesn’t respond, overriding them to prevent a full stall. Colgan 3407’s crew got the stick shaker and, later, the stick pusher, and the NTSB criticised the airline for not emphasising pusher response in training.
Why did pulling back make things worse on Colgan 3407?
Pulling back increases the angle of attack, the exact opposite of what stall recovery needs. It pushes the wing further past its critical angle instead of back below it. The NTSB’s official finding was that the captain’s wrong response to the stick shaker, pulling back instead of pushing forward, caused a stall the aircraft didn’t recover from.
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