July 2001Features

Perfect Fit

The Ergonomics Of Aeronautics

Climbing into the front seat of a training aircraft, reaching the rudder pedals, and seeing over the cowling can be a real challenge if you aren't of average height or are a teenager who's still growing. Even if you can reach the rudder pedals, you may not be able to see over the cowling. Being able to adjust our bodies to our environment (and vice versa) is something we take for granted every day, but rarely is getting it all adjusted properly as important as when you're learning to operate an expensive, potentially dangerous vehicle like an airplane.

Getting adjusted correctly could help you to avoid bumping another aircraft in a tiedown. It could even make the difference between a stall recovery and a spin. Because of this you might imagine that general aviation aircraft would be fully adjustable for people of all shapes and sizes, but that just isn't the case. Aircraft can only be adjusted so far. Often, they are much less flexible than the automobiles we're used to.

When it comes to making the adjustments, it's important to understand exactly where those adjustments should come from. This is because two people the same height - say five feet, four inches tall - each would have different leg and torso lengths and would need to adjust the aircraft differently to suit their individual frames. In simple terms, one person's 36-inch torso, with a leg length of only 28 inches, means his primary adjustment would be to move the seat as far forward as possible to compensate for a lack of full rudder authority. The other person in this example would leave the forward position alone because of her longer 31-inch leg length, but her shorter torso would require a seat-height adjustment to get a proper visual reference picture out the aircraft's windows.

These adjustments become a problem when the pilot's seat has gone as far as it can go, yet the student still does not have full rudder or yoke authority. Without full use of either of these controls, the student may not be able to fly safely. If you find yourself in this situation, you need to take steps to correct the problem - steps you'll likely have to repeat and modify with each model of aircraft you fly.

When leg or torso height is a concern, one of the first things you should do as you begin your pilot training is try various models of aircraft for fit and adjustability to your particular frame. It's also a good idea to look for fit differences between aircraft of the same model. If a particular aircraft offers you good seat height but a poor leg fit, another may suit you better. You should find where the best fit lies and where the least amount of adjustment is necessary. Being able to fly the aircraft comfortably using only the built-in adjustments is an advantage - it simplifies the adjustment process, means you don't have to drag around extra equipment, and will make you feel more comfortable and secure in the airplane.

But what if you need more adjusting than any of the available aircraft can accommodate? That scenario has come up often enough that there are special products to bridge the gap between body limitations and aircraft dimensions. Pilot booster seats are available from various sources and come in configurations to fit several needs. Simple rectangular cushions of various thicknesses (usually from one inch to four inches) to cushions with fully backed seats can be found by searching pilot supply catalogs and Web sites. Prices range from $20 to around $200 depending on complexity, thickness, and material composition of the cushion.

Many people try to use a standard throw pillow or an everyday bed pillow to gain seat height. These options are simply not firm enough to maintain a reliable thickness and may end up being virtually useless. Furthermore, the sheer size of bed pillows or larger throw pillows can mean they flow over the edges of the seat and could interfere with the trim wheel or other controls.

If leg length is where you need to adjust, then suitable shoes will get you in solid contact with the rudder pedals. Obviously there's a difference between the sole thickness of loafers, tennis shoes, and work boots. When even a work boot is not thick enough to bridge the gap, you'll need to find something more. There are a variety of different options for men and women.

Women's shoes come in a seemingly endless variety of styles, each with variants in sole and heel measurements that make the task of finding a proper thickness a little easier. Climb into the cockpit and make measurements (or at least estimates) of how much extra height you need and where you need it (remember that the ball of the foot, not the heel, is what you will normally want pressing on the rudder pedal). From there, a short time spent at the mall with a tape measure will probably yield something that's thick enough and won't break the bank.

Men's shoes are a different matter, especially if the distance to reach the rudders is significant. Even the thickest work boots may have only a one-inch sole and can be fairly expensive. Finding something with more than a one-inch sole for men can be very difficult, and if you want only a conservative shoe you may be limited to expensive ($200 or more) custom shoes. However, there are other choices if you feel like being a little "cool," thanks to recent trends in casual shoes for the teenage-to-20-something set.

A store offering "clubwear," or a store where the terminally black-clad shop, will often have shoes and boots with soles up to an amazing four-inch height. As a bonus you can get them in styles from plain and simple to those with outrageous designs emblazoned in vivid colors. If you have nothing like these stores near you, try shopping on the Web. Be advised that many of your choices here will run $50 or more for the thinnest of the thick (two inches or more) soles.

Remember that shoes that are too thick can be more of a hindrance than a help. It's useful to be able have a feel for the rudder pedals beneath your feet. And high heels have the potential to get caught on the rudder pedal or between the rudder and the floor. When you need more leg-length correction than shoes can reasonably provide, you may want to combine a moderately thick shoe sole with a cushion placed behind your back. Such cushions have the advantage of pushing you forward, effectively bringing your body (and your legs) closer to the controls.

If there's any doubt about the exact thickness of seat cushion or shoe sole you need, get the thicker of your available choices. You'll find that you're measuring against the aircraft's maximum seat adjustment, so you've got room to lower the seat or back it away if your booster cushion or shoe sole turns out to be just a bit too much for that particular aircraft.

As you create an adjustment regimen, it's a good idea to take a big-picture look at your cockpit. Perhaps you have full control authority in the rudder and yoke but find that your arms are too short to effectively reach the flaps, trim wheel, gear extension lever, or radios. If you find yourself turning into a contortionist when it's time to put in a new frequency or if you have to bob back and forth in your seat to reach the flap control, you need to make an adjustment. Wiggling around a lot or making abrupt movements of your upper body and head is not only distracting but can lead to spatial disorientation, especially in instrument conditions. You can compensate for short arms in much the same way as you would for short legs - with a seatback cushion that moves your entire body forward and closer to the controls.

If your legs are much longer than your arms, you may find yourself with a whole new set of problems. Moving the body forward enough to put the panel within reach may leave you with your knees in your chest. If this is you, try moving your body forward and lowering the seat. This combination may give you a little more leg room while still making up for short arms.

While proper body adjustment may be most critical in the cockpit, there are other aspects of flying that may require you to make adjustments as well. Make sure that every flight gets off to a good start with a thorough preflight. That means making adjustments if your body won't allow your eyes or hands to reach everything they should. If you can't see into the fuel tanks on a high-wing aircraft, use a step stool. The same is true if you need a little extra elevation to look for bird nests in the tail or if your arms won't reach the oil filler cap under the cowling. Never skip important safety measures just because you can't see or reach what you need.

Once you've made the adjustments, you'll discover that your aircraft has a better, more consistent feel. You can learn to control it proficiently because you've bridged the gap between your design and the aircraft's.


It's not always easy to find the tools you need at your local pilot shop or mall. Fortunately, the Internet can put these items within your reach regardless of where you live. Here are a few Web sites for cushions and shoes.


Chandler Industries

Noral Enterprises www.noralenterprises.com
(click Pilot Supplies)
Oregon Aero www.oregonaero.com/products.htm
Airsource1 www.airsource1.com/catalog/supplies/


Daljeets www.daljeets.com/creepers.html
ShoeBiz SF www.shoebizsf.com
Fantastique Shoes Fantastique shoes