Learn › Maneuvers › Maneuvering During Slow Flight

Maneuvering During Slow Flight

Slow flight is the takeoff and the approach, moved up to a safe altitude. It is where you learn to hold altitude, heading and airspeed while the wing is already working as hard as it can.

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

Why you fly it

Slow flight is flight at an airspeed just above the stall, with the wing at a high angle of attack and so little margin left that any further pitch, bank or load would set off the stall warning. Flown deliberately at altitude it is a training maneuver. Arrived at by accident near the ground it is a loss-of-control accident.

And you arrive near that condition more often than the practice area suggests. Every takeoff and every approach to landing is flown slowly with very little air underneath you — the two phases with the least energy, the least altitude and the least room to be surprised. Positive control of the airplane matters everywhere, but it matters most there.

So the point of the maneuver is not to fly slowly. It is to keep the airplane exactly where you put it while flying slowly, which is what an approach, a go-around or a short-field takeoff asks of you.

What changes as the wing slows down

Control surfaces work because air flows over them. In slow flight you are not giving them much of that flow, so every input needs to be larger than usual and the answer comes back late and soft. Disturbances damp out slowly as well, and untrimmed pressures will wear you down. Trim is not optional here.

Holding level flight this slowly takes a lot of power, because induced drag climbs steeply as angle of attack increases. High power and a high angle of attack together are the condition in which the left-turning tendencies are strongest — torque, slipstream, gyroscopic precession and P-factor all contributing, P-factor prominent among them — so slow flight demands sustained right rudder, not a nudge but a held input. Coordination is the first thing to go and the first thing an examiner watches.

Load factor matters more here than anywhere. Any increase in load factor raises stall speed, and near the stall you have no margin to give away: an abrupt or overbanked turn can stall a wing at a speed that felt comfortable a moment earlier wings level.

Behind the power curve

The power curve is simply the power required to hold level flight at any given airspeed. The speed at which required power is lowest divides the curve in two, and which side you are on determines how the airplane answers you. In front of the curve, the familiar side, flying faster takes more power. Behind it, flying slower takes more power.

Slow flight puts you behind the curve, in the region of reversed command, and the ordinary relationships invert: pull back and you will eventually descend, because the drag you added costs more than the pitch attitude bought. So down here you fly pitch for airspeed and power for altitude. Fly it the other way around and you will chase both.

Flying the maneuver

The speeds, the power settings, the flap limits and the configuration sequence itself belong to your airplane, not to the maneuver. Take all of them from the POH and from the airspeed indicator markings before you go — including carburetor heat if your engine wants it, cowl flaps, propeller and mixture, and the landing gear if you are flying something that retracts it.

1. Clear the area with clearing turns, and choose an entry altitude high enough that the maneuver and any recovery, including recovery from an unintended stall, are complete no lower than 1,500 feet AGL. That figure is where you finish, not where you begin, so enter well above it.
2. Set the propeller, the mixture and the rest of the configuration as your POH specifies, then pick a prominent visual reference and bug the heading — decide that before you get busy.
3. Reduce power and hold altitude with back pressure as the speed decays. Add each stage of flaps as the speed enters its permitted range, and be ready for the pitch change that comes with it: whether the nose rises or drops, and how much, is a characteristic of your airplane, so learn it from the POH and from flying it. Correct it promptly with pitch rather than trading the altitude away.
4. Keep slowing until the stall warning activates. Note that indicated airspeed — the whole maneuver is built around it.
5. Add power to stop the deceleration and hold altitude, and settle a few knots above the warning speed so the horn stays quiet. Trim off the pressures. Keep the right rudder in.
6. Hold that state: straight and level, gentle turns, climbs and descents as asked. Pitch for the airspeed, power for the altitude, ball centered, eyes mostly outside.

To recover, smoothly bring in full power and lower the nose only as much as it takes to reduce the angle of attack and let the airplane accelerate — the goal is minimum altitude loss, not a dive. Retract flaps in stages at the speeds your POH gives, anticipating whatever pitch and trim change your airplane makes as each stage comes up, and retrim as the pressures change. At cruise speed, reduce power and settle back into level flight.

The standards

Tolerances tighten with the certificate, and on both tests the maneuver and its recovery are completed no lower than 1,500 feet AGL. On the private test you hold altitude within 100 feet, heading within 10 degrees, airspeed +10/‑0 knots, and any specified bank within 10 degrees. On the commercial test it is 50 feet, 10 degrees, +5/‑0 knots, and 5 degrees of bank. The airspeed tolerance has no minus side on purpose: slower is not close enough, it is closer to the stall.

What goes wrong

Most failures start at the entry. Too little back pressure as the power comes off and you sink out of your altitude; too much and you decelerate into the stall warning before the airplane is configured. Both are cured by flying the attitude outside rather than reacting to the altimeter.

The next problem is rudder. Insufficient right rudder at high power and low speed puts the airplane out of coordination, and an uncoordinated wing near the critical angle of attack is how a stall becomes a spin.

After that: fixating on the instruments instead of dividing attention between attitude, orientation and traffic; failing to anticipate the pitch and power change every time the flaps move; managing power in coarse handfuls instead of small corrections; flying the whole thing out of trim; and — the one that matters most — hearing the stall warning and doing nothing about it. Failing to clear the area belongs on the list too, since it is the only error here that can involve someone else's airplane.

The air gets a vote as well. Turbulence and wind shear move you around at exactly the speed where you have least authority to answer, and high density altitude can mean the power needed to hold level flight is more than the engine will give you that day.

Where you meet it next

Slow flight opens the stall sequence on the ACS: slow flight first, then power-off stalls, then power-on stalls, with accelerated stalls beyond them. It is the controlled approach to the edge those tasks step over, and the rudder, the trim and the power curve you learned here are what carry you through all of them.

Beside it in the same area of operation, the Flight Instructor ACS carries Task B, Demonstration of Flight Characteristics at Various Configurations and Airspeeds. That one is a demonstration task: your instructor flies it and talks it through, clean and then in landing configuration, recovering by lowering the pitch attitude alone with the power left where it is, so you can watch what the wing does on its own. It is a teaching demonstration and nothing more — the stall recovery you fly for real still reduces the angle of attack first and then adds power.

Outside the practice area you meet slow flight on every approach, in every go-around, and the first time you are asked to follow slower traffic on final. The lessons on power-off stalls, power-on stalls, the go-around and the short-field takeoff all start from the airplane you have just learned to hold steady. More ground school lessons.