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Zero Sideslip in Multi-Engine Flying: The “Secret” That Turns Engine-Out From Ugly to Manageable

If you’ve flown a twin with an engine “failed” (real or simulated), you’ve felt it:

  • the nose wants to yaw

  • the airplane wants to roll

  • the ball refuses to behave

  • your feet are suddenly doing cardio


Then an instructor says, “Set zero sideslip,” and—almost magically—the airplane stops feeling like it’s trying to wrestle you.


Zero sideslip is one of the most useful concepts in multi-engine flying because it’s the difference between:

  • fighting the airplane (and bleeding performance), and

  • flying the airplane efficiently (and preserving what little single-engine climb you have).


Let’s unpack what it is, how to find it, and why it matters.



Study this full length lesson (video, podcast, flashcards, and quiz) here: Full Length Lesson >


What Is “Sideslip” in the First Place?

Sideslip is when the airplane’s flight path isn’t aligned with the airplane’s longitudinal axis.


In normal coordinated flight:

  • the nose points where you’re going

  • the relative wind hits you straight on

  • you have minimal extra drag


In a sideslip:

  • the nose points one way, you’re moving another

  • the airplane is “crabbing” through the air

  • drag increases and performance goes down


In a twin with one engine inoperative (OEI), sideslip shows up because:

  • one engine is pushing

  • one isn’t

  • the airplane yaws toward the dead engine unless you stop it


So What Is “Zero Sideslip”?

Zero sideslip means you’ve set the airplane so the relative wind is straight down the nose—even though you’re in an asymmetric thrust situation.


You’re still using rudder (because you must), but you’re using it in a way that minimizes the extra drag and maximizes the remaining performance.


Think of zero sideslip as:

  • “The most aerodynamically efficient way to fly a twin on one engine.”


Why Zero Sideslip Matters So Much in a Twin

When an engine quits, the airplane’s single-engine climb margin is often small. In many light twins, it might be:

  • modestly positive,

  • near zero, or

  • negative depending on weight and density altitude.


That means any unnecessary drag is a big deal.


Sideslip creates drag—and drag kills OEI climb

If you’re slipping while trying to climb on one engine, you’re:

  • increasing parasite drag

  • increasing induced drag (because corrections often increase angle of attack)

  • effectively “wasting” thrust just to shove air sideways


Zero sideslip is how you stop paying that drag penalty.


The Classic Setup: “Step on the Good Engine” + Slight Bank

When an engine fails, you generally:

  • apply rudder toward the operating engine (“step on the good engine”)

  • and establish a slight bank into the operating engine (often just a few degrees)


That small bank does two key things:

  1. It helps counteract yaw with a horizontal component of lift

  2. It reduces how much rudder you need, which reduces rudder-induced drag


This combination is what most people mean operationally when they say “set zero sideslip.”


The Ball Is a Liar (In OEI Flight)

This is a big learning moment for multi students:

In engine-out flight, a perfectly centered ball often does not equal zero sideslip.


Why? Because the ball measures lateral acceleration, not “relative wind aligned with the nose,” and because in asymmetric thrust, the control inputs that minimize drag may produce a ball position that looks “wrong” compared to what you’re used to.


The practical takeaway

  • Use the ball to keep yourself from doing something extreme

  • But don’t treat “ball centered” as the definition of zero sideslip in a twin OEI condition


Your POH/training guidance will tell you what reference to use in that aircraft.


How Pilots Actually Find Zero Sideslip (Three Common Methods)

Different airplanes and training programs emphasize different cues. Here are the common ones you’ll see:


1) The “2–3 degrees of bank into the good engine” method

Many instructors teach a small bank toward the live engine as a reliable baseline. It’s simple, stable, and usually gets you close to the best OEI performance setup.


  • Pros: fast, easy, works well in most training twins

  • Cons: not as precise as other methods, and “2–3 degrees” is still an approximation


2) The “rudder trim / performance” method

You set directional control and then fine-tune using rudder trim and bank until:

  • the airplane feels stable,

  • your control pressures are manageable,

  • and your performance (climb/altitude hold) is best.


  • Pros: practical and performance-based

  • Cons: requires enough altitude/time to assess trend


3) The “yaw string” method (the most direct)

Some twins (and many multi training setups) use a yaw string on the windshield. When the string is straight back, you’re at (or very near) zero sideslip.


  • Pros: direct indication of relative wind alignment

  • Cons: not every airplane has one installed


Zero Sideslip vs. Vmc: Related, But Not the Same

Zero sideslip is about efficiency and drag minimization.


Vmc is about controllability—the minimum speed at which you can maintain directional control under worst-case conditions.


They interact because:

  • an inefficient sideslip can increase your workload and reduce control margin

  • but chasing zero sideslip doesn’t mean you’re safe if you’re slow


The engine-out priority is still:

  1. Control / airspeed (stay well above Vmc)

  2. Configuration / secure the engine

  3. Efficiency / zero sideslip

  4. Performance / Vyse (blue line)


Zero sideslip is a huge help—but it doesn’t replace airspeed discipline.


Where This Shows Up Most: Engine Failure After Takeoff

In the real world, the moment you most want zero sideslip is when:

  • you’re low

  • you’re slow-ish

  • you’re high power

  • you’re busy


That’s also the moment you have the least spare bandwidth.


That’s why instructors often build a habit pattern:

  • rudder toward the operating engine

  • slight bank into the operating engine

  • pitch to the correct OEI target speed

  • clean up and secure


Done correctly, the airplane feels much less chaotic, and you preserve the best chance of holding altitude or achieving a climb.


Common Errors Students Make With Zero Sideslip

“I centered the ball, so I’m good.”

Not necessarily.


“I banked too much into the good engine.”

Too much bank increases drag and can actually hurt OEI performance. The bank is small—enough to help, not enough to carve turns.


“I used aileron instead of rudder to fix yaw.”

Aileron fixes roll. Rudder fixes yaw. If you try to solve yaw with aileron, you often end up with more sideslip and more drag.


“I trimmed too early.”

Get the airplane stabilized first. Then trim. Trimming while you’re still identifying/feathering/configuring can lock in a bad setup.


Bottom Line

Zero sideslip is the aerodynamic sweet spot for flying a multi-engine airplane with one engine inoperative. It minimizes drag, reduces workload, and preserves what little single-engine performance you have.


The practical technique is usually:

  • rudder toward the operating engine

  • a slight bank into the operating engine

  • fine-tune using your aircraft’s recommended cues (sometimes a yaw string, sometimes bank angle, sometimes performance)



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