Slip/Skid and “Cross-Coordination!”

Many learners (and even some experienced pilots) believe: “cross-controlled flight is inherently dangerous.” As a result, these pilots do not use their rudder effectively in flight. The “slip to land” task in the ACS is regarded by many pilot applicants as a mysterious lapse in safety on the part of the FAA. They fly glassy-eyed and simultaneously intone: “we are cross-controlled, and going to die” when flying this maneuver down to the runway. Inevitably, it is flown so fast and timidly, that it is of no use at all. And most applicants do not understand why a slip is both safe and useful while a skid is inherently dangerous (they get it half right). An advanced concept like “cross-coordinated” is truly a “bridge too far” – but we will get to that later. Here is the basic “cross-controlled starter kit.”

Why a Slip is Safe?

A skidding turn has an excess rate of turn for the amount of bank applied. We skid any time we create a turn with the rudder (or apply too much rudder in the direction of the turn). This is dangerous because both bank (vectored lift?) and yaw are acting together – in the direction of the turn. If we were to stall in this configuration, this combination of forces could easily lead to a spin. The slower wing (higher AOA) is on the bottom too, so less time to react.

Unfortunately,  the “feel” of a skid is “comfortable” to most people from driving automobiles.”Cornering flat” on the road is well-ingrained and familiar. By contrast, most new learners initially dislike the “feel” of a slip. When you find a pilot that can really slip well, you usually have found a “good stick!”

The slip has too little rate of turn (yaw) for a specific bank angle. Here the force of lift and yaw are acting in opposition (step on the high wing and yaw away from the turn). A power-off stall in a full slip is actually a non-event. This is a powerful demonstration for a prepared learner when conducted at a safe altitude. This demonstration creates cognitive dissonance which inspires deep learning: “We are fully ‘cross-controlled’ and stalling, what is going to happen?” Although obviously inappropriate for an unprepared (still fearful) learner, this maneuver at the right time, can be a life-changing learning opportunity. Just remember to recover the slipping stall with pitch down (unload) only. Adding power in this configuration energizes that rudder (providing relative wind over the tail) and can create an exciting “over the top”spin.

So What is “Cross-Coordinated?”

“Cross-coordinated“ describes when the ailerons and rudder are applied against each other – in opposition – to create coordinated (more efficient) flight. For advanced pilots, visualize the last half of a right chandelle: the right rudder is almost to the floor and the ailerons are dramatically opposite to roll the wings level. Your plane is coordinated, close to a stall, and the controls are almost totally in opposition. (Demonstrating that power-off slipping stall would be a good prelude to this chandelle to create confidence and understanding).

Every take-off, performed correctly, requires “cross-coordination.” The right rudder pressure applied to counter the yaw from P-factor and slipstream requires left aileron to keep the wings level “cross-coordinated!” Remember, every aileron or rudder application has a secondary effect (in this case “proverse” roll).

For most pilots, a CFI has to carefully explain these forces and “give permission” to “cross the controls,” otherwise the plane will be climbing sideways. Watch carefully as you “tune” the plane to level the wings and coordinate -enjoy that increased rate of climb that comes with reduced drag. This benefit is especially noticeable in less powerful prop planes.

In the pattern, every left climbing turn will require right rudder (against the turn) or the plane is skidding (the way many people fly a left pattern). The right-hand climbing turn requires “bottom” rudder and opposite aileron (or it’s slipping). Notice the application of control pressures is not symmetrical climbing left and right. This confuses early learners. It is essential to explain this immediately or learners will be confused (and may also be unsafe for the rest of their flying career). And a simple flight test cannot fix this kind of ignorance; DPEs are merely gatekeepers, the CFI is the “influencer.”

The young lady here had over 80 hours in training and was quite happy demonstrating a beautiful “skid to final” on a flight test. Despite her poor instruction, I was also sure she would be a pilot – with another hour of training (and another 8710) – despite her confusion. Even more remarkable was a new CFI, who graduated from a large university flight program. He demonstrated a full “skid to land” for me – believing the whole time he was slipping – stuff happens!  This subject will be the focus of our August 11th SAFE Webinar. As dedicated CFIs (and passionate pilots) we certainly have our work cut out for us. Fly safely out there (and often)

Airventure (OSH)24 has been added to our “SAFE Toolkit” App (free download). This App has directions to all our events and provides push notifications of all SAFE events at the show -“allow notifications!” Additionally, the toolkit is chock full of CFI resources and helpful hints for applicants in the “Checkride-Ready™” tab (DPE best advice for flight test success).

Register and attend our August 11th Webinar on “Learning Rudder and Cross-Coordination.”  See  “Teaching Rudder.” and “Cross-Coordinated.“