The subtle differences that are encountered when transitioning from a high-wing to a low-wing, or vice versa, will challenge our muscle memory, which in turn affects how we control the airplane.
One of the basic clichés in life is that learning anything is quite often a matter of doing it over and over until you get it right. Of course, engaging in that kind of repetition makes an insidious assumption that what you're doing over and over is being done right, which often isn't the case, causing us to get really good at doing something wrong. However, even if we're doing it exactly right, there's another possible problem: Repetition gives our muscles internal routines, a memory, that can work against us in new situations, and sometimes the habits formed are hard to break.
New Airplanes: Wow, This Is different!
When checking out in new airplanes, our experience (or lack thereof) can work for us or against us.
When we're students, we know flight only as interpreted by the airplane in which we're learning. Every little thing our instructor pounds into us is specific to this single flying machine. Although, airplane to airplane, the concepts of control are basically the same, it's not until we get ready to fly our first new airplane after earning our PPL when we realize that the nuances of controlling that specific airplane have become ingrained in our subconscious thought patterns.
When checking out in a new airplane, that muscle memory is usually so strong that it takes conscious effort to overcome it and not let our hands automatically make motions that may not be suited to the new bird.
All of us remember our first high-wing to low-wing, or vice versa, transition. The stage is initially set by the overall strangeness of having the wing located where it isn't supposed to be. Intuitively, we know new scenarios are about to unfold. What we don't know is that some differences represented by the new scenarios won't be procedural but will be in the form of perceived differences in the way the airplane feels and how it reacts. And these subtle differences challenge our muscle memory.
If we learned in a Cherokee, for instance, and are transitioning to a 172, the small difference in wing loading between the two makes itself felt. Even though we don't actually know what's causing the difference, we definitely feel it, and it affects how we control it. Initially, we feel as if we're transitioning from a rock-solid airplane (the more heavily wing-loaded Cherokee) that plows through the air, to one that floats on the air, courtesy of the Cessna's lighter wing loading and higher aspect ratio. When we move our hands, we get a subtly different result. It sometimes takes several hours before we overcome the muscle memory that makes us expect one kind of result, when we get another.
One of our biggest surprises during that kind of transition comes when we turn final and drop full flaps. Piper-trained pilots are almost always caught unaware by the much larger pitch change the Fowler flaps on the Cessna produce. They're also surprised when they make the first full-flap approach and find that Cessna flaps really do work: During the flare, they have to be careful not to let their hands automatically pull the nose up at the same rate they would a Piper and cause the airplane to balloon. At the same time, with full flaps, it's all they can do to get the nose up for a main-gear touchdown. Conversely, Cessna-trained pilots wonder if the flaps on the Cherokee even went down, as they habitually start to move the yoke and reach for the trim, then realize a) the trim isn't where they reached and b) they don't need nearly as much trim anyway.
Our muscle memory can cause us heartburn while doing even basic tasks, like making a simple, garden-variety turn in a new airplane. If by some stroke of luck, the newly minted pilot learned in an Aeronca Champ or something similar, he's going to find turning a Cherokee or a C-172 to be an exercise in restraint. The Champ taught him to "lead" slightly with the rudder, so a fair amount of rudder went in more quickly than the ailerons. This helps keep the overabundance of adverse yaw under control. His Champ instructor drilled this into him from day one, but his 172 instructor will have to drill it out of him. And that kind of tiny muscle memory is very difficult to unlearn.
Oddly enough, newbie pilots may transition to a new airplane easier than those with more experience in a given type, because a new pilot's habits aren't as deeply ingrained. Having 100 hours in a Cherokee and then transitioning to a Cessna while still a very malleable, low-time pilot is one thing. Having 500 hours in the same airplane and transitioning can be something entirely different.
Big Airplane To Little Airplane
Aviation is loaded with stories about the adventures of airline pilots learning to fly small airplanes, but this is doing airline pilots a disservice. The exact same problems exist for anyone used to flying heavier, larger airplanes, when learning to fly much smaller airplanes. And vice versa. Think about it: You've spent 20,000 hours in cockpits that are 30 feet off the ground, so letting a runway come up to within 10 feet or so of eye level is bound to spark some primordial survival response. The little voice in your brain is going to be squalling, "Pull up! Pull up!"
The reverse is also true: Regardless of what we see in adventure movies, a Cessna pilot in the left seat of a 747 in place of the sick pilot (why do they ALWAYS eat the fish rather than the chicken?) will most likely drive it into the runway. He'll flare too late because that's the way he's used to seeing it: Cessnas aren't meant to be landed at 40 feet.
Examples like the above show that the eye-hand coordination thing is very real, and our eyes are subject to "memory" just as much as our muscles are. We get used to things looking a particular way at a particular time, e.g., during flare, making turns, etc. The visual signals go into our mental processor and come out through our hands in the form of muscle memories, and we wind up having to retrain our eyes as much as we do our hands.
Takeoff Timing And Density Altitude
Throughout aviation's history, muscle memory has played a diabolical role in any number of density-altitude takeoff accidents. Even though pilots know they should wait until the airplane is indicating a proper speed before attempting to lift off, they don't realize how much timing and muscle memory control their reactions until they're faced with a serious high-density altitude challenge. Even when forewarned, they'll often make the same mistakes.
It's not unusual when taking off at high altitude for flatland pilots to line their ever-faithful 172 up on the runway, see 4,000 feet of pavement in front of them, and breathe a sigh of relief. With that much runway, they aren't worried that they're right at gross, or that the OAT may be bumping 100 degrees, and they're at 5,500 feet MSL. On top of that, they didn't lean to peak rpm. A chain of errors borne of a form of muscle memory: This is the way that they've always done it, and they don't recognize that this is a different ball game. Call it mental muscle memory.
Airline pilots who transition to smaller airplanes will be faced with muscle-memory problems, and during landings will tend to flare much higher than they should. Likewise, Cub pilots who move into a much larger airplane will flare too late because they're responding to the sight picture that they're used to.
As the power comes up, the airplane begins its sluggish roll down the runway. This is where muscle memory gets them in trouble. They let it roll longer than usual, as they know they should, but, after it has rolled longer than they have ever seen it roll before, their habits/muscle memory start to nag at them. The airplane should be ready to fly by now, right? They yield to temptation and make the mistake of pressuring the yoke back, trying to coax it off the ground rather than letting the airplane make the decision itself as to when it's ready to fly. They keep gently tugging on the nose until the airplane sags into the air in ground effect. Then it usually flops back down on the pavement, but they coax it off again, all the time eating up runway. If they would have left it alone and let it roll until it had sufficient speed, it would indeed fly off with positive rate of climb. Unfortunately, once they start dragging it into the air against its will, they waste much needed energy and runway, thereby sealing their fate.
In these kinds of situations, pilots are letting their habits and muscle memories, which were built up from many prior flat-country takeoffs, overcome what they were told in ground school about these kinds of situations. Intellectually, they know that if it doesn't have the proper indicated airspeed, it's not going to fly. However, they've rolled so much farther than they've ever seen an airplane roll before that they just can't believe that it's not ready to fly. But, it's not, and the results are often tragic.
In the foregoing paragraphs, we've dealt with a rather narrow series of situations, but there are actually lots of scenarios where muscle memory can bite us in the butt. The key to rehabilitating those muscles and making them fit any new situation is to recognize exactly what it is that this particular airplane and this particular situation demand of us. More important, we have to recognize that what we've done in the past may or may not work in this new situation.We don't want old habits to breed new problems.