In this article you’ll learn all about power-on stalls.
A key element to learning to control your aircraft through its entire flight envelope is working on your skills of flying it as slow as it will go.
Slow flight is all about feeling how the plane reacts on the edge of a stall. To understand it, you go ahead and stall it to see what happens.
Of course, you do this safely, at high altitudes, as part of the learning process. It’s critical to practice these maneuvers as this is how the plane is flying — slowly — right after take-off and right before landing.
Once you’ve started working on power-off stalls, the next step is the power-on stall.
Where power-off simulates approaching to land, power-on stalls simulate that you’ve just taken off.
Power-on stalls have a completely different feeling about them, thanks to all that engine torque and P-factor pulling it to the left as you apply more power.
Here’s a look at the power-on stall as a maneuver and why it’s so important to get it right.
What Is a Power-on Stall?
A power-on stall is better described as a departure stall. That means that it simulates a situation where the aircraft is stalled after take-off, so the power level is high, and the aircraft is set up like it just left the ground.
This usually means the flaps are up, but some planes may have 10 degrees of flaps set.
To safely practice the maneuver, you take the plane to a safe altitude (so that recovery can be made no lower than 1,500 feet AGL). From there, you slow down to take off speed and establish a steep departure climb, usually at Vx.
You then induce the stall by pitching up until the stall occurs.
During a power-on stall, the left-turning tendencies of most single-engine aircraft are at their maximum: the thrust is high, the airspeed is low, and the angle of attack is extreme.
This means you must be prepared to apply plenty of right rudder to keep the aircraft coordinated throughout the maneuver.
Failure to use the rudder correctly can result in one wing stalling more severely than the other, which is the perfect setup for entering a spin.
Power-on Stall Scenarios
As stated, power-on stalls are designed to simulate problems during departure — right after takeoff. There are a few classic scenarios in which pilots can get into trouble here, but they stem from improper airspeed control on climb out.
Flying a plane safely nearly always comes down to maintaining control, which means following the flight profiles you are taught.
For example, in most Cessna 172s, you rotate at 55 knots and climb at either Vx or Vy until you are at a safe altitude to transition to a faster cruise climb.
When might it become a problem? Here are a few scenarios that have led pilots into trouble.
The first risk might come from departing from a short field with an obstacle, say a line of trees, in the departure path.
Let’s say a pilot did not do their homework, and they’ve departed a runway that turns out to be too short.
Upon departure, it becomes evident that the plane will not clear the trees, so the pilot continues pitching up in a vain effort to get more altitude. Instead, the plane stalls and crashes.
It’s vitally important (and required by FAR 91.103, Preflight Action) that pilots check the airport’s takeoff and landing distances available and the aircraft’s takeoff and landing performance distances needed.
This should be done prior to every flight, and the rule is designed to prevent a pilot from taking off from a runway that is too short.
When looking at this regulation, it becomes clear that the issue isn’t as simple as finding a runway long enough.
Several factors might cause the plane to perform worse than expected. In other words, the plane might have made the same takeoff on the same runway hundreds of times successfully, but today, things might be different.
For example, a plane will not perform as well on takeoff or climb out if loaded heavier than usual — or worse, over maximum gross takeoff weight.
Density altitude is another insidious danger that could lead to a power-on-stall scenario.
Hot weather and high airport elevations mean that many aircraft use a lot more runway and climb slower once airborne. For many pilots, waiting for cooler evening temperatures may be the only solution.
Finally, one more surprise environmental factor could cause an unforeseen run-in with the trees: a tailwind.
While headwinds help the plane get off the ground and climb faster, a tailwind does the opposite. The difference is surprising and must always be considered.
The Maneuver — Power-on Stalls and Recovery
Like power-off stalls, you should practice power-on stalls and recoveries to both the incipient and full stall.
You may perform the maneuver with any combination of power and flaps that are applicable to departure in your aircraft.
Furthermore, you should practice entering these stalls in turns (15 to 20 degrees of bank, no more), as this simulates conditions when turning from upwind to crosswind in the traffic pattern.
In most training aircraft, you will always practice power-on stalls at full power.
However, in some high-performance planes, it’s common to perform the maneuver at a slightly reduced power setting to reduce the deck angle and time it takes to induce a stall.
When inducing the stall from slow flight, it’s essential to be realistic.
Some pilots like to continue pulling back in an improbable manner that induces the stall quickly. A better technique is to set a pitch that results in a steady and slower loss of airspeed until the stall occurs.
Here are the steps for completing a power-on stall and recovery in the typical training airplane.
- Establish at an altitude that will allow recovery no lower than 1,500 feet AGL.
- Complete clearing turns and the Pre-Maneuver Checklist.
- Establish slow flight – clean: While maintaining altitude, reduce power to about 1,200 RPM and increase the angle of attack to hold altitude. Slow to Vr and trim to hold the airspeed.
- Apply full throttle (or specified RPM) and pitch into a steep Vx departure climb.
- Continue increasing your pitch by pulling the stick back (increase the angle of attack) until the stall occurs.
- Push the stick forward and lower the nose to reduce the angle of attack. Keep the wings level.
- Ensure full power is set and pitch for the horizon.
- Level off at the original starting altitude and return to cruise speed.
FAA Graphic: Airplane Flying Handbook
Stalls and recovery techniques are covered in the FAA’s Airplane Flying Handbook, Chapter 5: Maintaining Aircraft Control, Upset Prevention and Recovery Training.