Ground Loop Prevention: AFH Chapter 13

Handbook Reference

AFH Ch 13

13.ground-loop-prevention. Ground Loop Prevention in Tailwheel Airplanes

A ground loop is an uncontrolled, rapid rotation of a tailwheel airplane in the horizontal plane while on the ground. It typically occurs during the landing roll or takeoff roll, and once it begins it can develop with surprising speed and violence. Because the center of gravity (CG) of a tailwheel airplane is located behind the main landing gear, any sideways deviation of the tail produces a moment that tends to swing the tail farther in the same direction. Left uncorrected, this self-aggravating yaw rotates the airplane until the tail effectively trades places with the nose. Severe ground loops can collapse a gear leg, drag a wingtip, scrape the propeller, or damage the airframe.

Why Tailwheel Airplanes Are Susceptible

The geometry of a conventional-gear (tailwheel) airplane makes it directionally unstable on the ground:

The CG is aft of the main gear pivot points.
A small yaw displacement places the CG outboard of the main wheel track, generating a centrifugal force that acts as a lever arm to increase the yaw.
The tailwheel produces little corrective force compared to a steerable nosewheel, especially when light on its tire after touchdown or during a wheel landing.
Crosswinds, brake asymmetry, and uneven runway surfaces add yawing moments that the pilot must immediately neutralize.

By contrast, a tricycle-gear airplane has its CG forward of the main gear, so any yaw produces a restoring moment — making nosewheel airplanes inherently more directionally stable on the ground.

Primary Causes of Ground Loops

Late or insufficient rudder input. The pilot fails to detect or correct a small yaw before it builds momentum.
Improper crosswind technique. Failure to lower the upwind wing with aileron and apply opposite rudder, or relaxing those inputs after touchdown.
Touchdown not aligned with the direction of motion. Landing in a crab or with drift loads the gear sideways and starts a swing.
Excessive or asymmetric braking. Heavy braking on one wheel — or any braking before the tailwheel is firmly planted — pivots the airplane around that wheel.
Premature relaxation of controls. The landing roll is not over until the airplane is stopped and the controls are properly positioned for taxi.
Bouncing or skipping that allows the airplane to land slightly sideways.

Prevention Techniques

Ground loop prevention is built on three habits: fly the airplane until it is tied down, keep the longitudinal axis aligned with the direction of motion, and make small, immediate corrections.

Maintain runway alignment. Use rudder to keep the nose tracking straight down the centerline through rollout. Fix your visual reference well down the runway, not just over the cowl.
Use proper crosswind controls. During the rollout, progressively increase aileron deflection into the wind as airspeed decreases until the control wheel reaches the stop. Hold opposite rudder as required to prevent weathervaning.
Stick with the stick. After a three-point landing, hold the stick fully aft to keep the tailwheel firmly on the surface for steering authority. After a wheel landing, hold forward elevator pressure to pin the mains, then transition to full aft as the tail lowers.
Anticipate, don't react. Look ahead, feel the rudder pedals, and apply small inputs at the first hint of yaw. Treat the rudder pedals like a piano — many small touches, not one large stomp.
Use brakes sparingly and symmetrically. Differential braking is a steering tool of last resort during landing rollout; aerodynamic controls and the tailwheel should do the work first.
Land aligned. Eliminate drift by the moment of touchdown, using the wing-low slip method in a crosswind so the upwind main wheel touches first.

Recovery When a Swing Develops

If a yaw begins to develop despite prevention:

Apply opposite rudder immediately and decisively — the correction must lead the swing, not chase it.
Add power if directional control is being lost. The blast of slipstream over the rudder can dramatically increase its effectiveness, and acceleration can give you the option to abort the landing and go around.
Avoid braking on the inside wheel of the swing; it will pivot the airplane further in that direction.
Do not over-correct. As the swing stops, neutralize and then reapply rudder as needed to track straight. Pilots who hold full opposite rudder too long simply start a ground loop in the other direction.

Practical Examples

A Cessna 170 landing with a 10-knot left crosswind requires right rudder to prevent weathervaning into the wind and left aileron held into the wind to prevent the upwind wing from lifting. If the pilot relaxes either input on rollout, the airplane will weathervane left, the CG will swing right, and a ground loop to the left becomes likely. The recovery — prompt right rudder, possibly a burst of power, and re-establishing left aileron — must be made within a second or two.

Ultimately, ground loop prevention is a matter of pilot discipline. The transition pilot who treats every landing as a continuing flying task, rather than the end of the flight, will keep the airplane straight.

Oral Exam Questions a DPE Might Ask

Q1Why are tailwheel airplanes more prone to ground loops than tricycle-gear airplanes?

The center of gravity sits behind the main landing gear, so any yaw moves the CG outboard of the wheel track and creates a moment that worsens the yaw. In a nosewheel airplane the CG is forward of the mains, producing a stabilizing moment instead.

Q2What control inputs should you use during the landing rollout in a left crosswind in a tailwheel airplane?

Hold left aileron into the wind — increasing to full deflection as the airplane slows — and use right rudder as needed to prevent weathervaning. After a three-point touchdown, hold the stick fully aft to keep the tailwheel firmly planted for steering.

Q3If a ground loop begins to develop, what is your immediate action?

Apply prompt, decisive opposite rudder to stop the swing, and consider adding power to increase rudder effectiveness or to go around. Avoid braking on the inside wheel of the swing, and neutralize the rudder once the yaw stops to prevent over-correcting into the opposite direction.