Restraining Orders

An instrument rating may be the best present a pilot can get (after a brand new airplane), but there is another gift that might prove just as much of a lifesaver. Unfortunately, it won’t feel like much of a present to most of us — we already have it. The problem is that some of us don’t use it. A proper restraint system, and in particular, shoulder harnesses can save your bacon just as well as any additional training you could get, but (according to the latest iPilot poll) about a quarter of us are still flying airplanes without them. Like Jack Lemmon in ‘Tribute’, I happen to like it here. This is just another one of those things about some people, like rampant obesity or smoking cigarettes, that makes me shake my head and wonder whether it’s just ignorance, or an impatient curiosity about the next world. Then again, maybe if I worried less about how many things are out there waiting to exterminate me, I might live a little longer. Regardless, I do know we choose to take life by the horns when we fly. I prefer to do that from a firm footing, is all.

If your airplane’s return to earth ever involves something other than a runway, the one thing inside the cabin that is there for the specific purpose of helping you save face, if you get my drift, is a shoulder harness. People have studied this stuff, and the numbers show that the use of shoulder harnesses reduces major injuries by almost 90%, and lowers fatalities by 20%. Shoot, we all wear seat belts. The rules say we must. But we all know Newton’s first law, that says ‘when the airplane in motion becomes an airplane forcibly restrained, everything inside will remain in motion‘. That includes your upper body (though restrained at the hips) flailing forward and smashing into the panel, then the yoke, etc. Yes, CFR 14 Part 91.105 and 91.107 are full of seatbelt shalls, but they also have ‘ifs‘ including ‘if installed…’ Yes, seat belts will protect you, but only in minor impacts. The shoulder harnesses is there to do the rest of the job.

If your airplane was made after December 12, 1986, you’ve already got at least a three-point restraint system… by law. Unfortunately, a lot of the airplanes we find ourselves in are more than 16 years old — consider it the downside of parading around in the flying antiques that make up much of the general aviation market these days. If you don’t have them in your aircraft, you should know that they make them for almost every airplane that exists. The ‘hard points‘ for mounting are often already there, and one manufacturer, Cessna, sells shoulder harnesses at cost. There are four basic types of shoulder harness layouts:

  1. The inertial reel type with a strap over each shoulder may be the most practical of the four kinds… and the most expensive.
  2. The double-strap, fixed mount also provides restraint for both shoulders, but is slightly more ‘hassle‘ to get into and some pilots may find the ever-hanging straps an eyesore. Safety vs. fashion…
  3. Then inertial reel, single shoulder is the same as the inertial reel, but only restrains you by the one shoulder, which could prove unfortunate if you experience side loads as a result of impact.
  4. The single-strap, fixed mount variety will do the job, but comes with the mild downsides offered by types 2 and 3, above.

NOTE: In addition to having at least a three-point restraint system and nicer looking interiors, newer aircraft also have stronger seats, which can absorb greater impact loads.

In this instance, it’s more a matter of fashion than religious fervor. Seat belt straps should be worn low, over your hips; no higher, no lower. Safety engineers have determined that seat belts should actually be at about a 55 degree angle up from the centerline of the airplane and otherwise should bisect the angle between the seat back and seat bottom. Shoulder straps must find their attach point no more than 40 degrees below your shoulders — otherwise, sudden forward movement could result in compression of the spine. The ideal attach point is slightly above and behind the shoulders. The straps shouldn’t rub your neck, and your torso’s center of gravity should be between the shoulder harness and seat belt. It is this center of gravity issue that may cause you to have the seat belt buckle moved from front and center (where it usually fastens), over to the side of your hip to accommodate the proper shoulder harness strap attach point. If you have the double-strap type though, it’s a good idea to add a tie-down strap (or submarine belt) going from the center buckle to the center forward seat edge. This helps counter the upward pull caused by falling into the shoulder belts. Needless to say, when the buckle is unlatched, that should release both shoulder and seat belts. When worn, make ’em tight, but not uncomfortable. Yes, you might have to loosen the strap to reach the fuel selector valve, but shoulder harness design actually requires that even altitude-challenged (okay, short) pilots should still be able to reach the controls with their shoulder harnesses fastened properly.

If you’re about to come to a stop without benefit of a surface intended for that purpose, remember: fly the airplane into the crash, as slowly as you can, but don’t stall it in. Use the wings to absorb the impact, but only if it won’t yaw you sideways — the cabin and those belts were designed to absorb frontal impacts. If at all possible, pick the surface that you think will spread your deceleration over the greatest distance. Why? Because your chances of having a bad day increase exponentially as stopping distance decreases. Plus, if you’re a guy, and you’re reasonably healthy, you can probably take 20 g’s for a second or so. If you’re a woman… you can probably handle even more. (Which, as my wife points out, further redefines the notion of the weaker sex.)

Example 1: Let’s say your engine quit over inhospitable terrain and you did the best you could with a field of bushes and weeds and — never having crashed before — you only got the airspeed down to 75 knots. Now imagine that in one second, it was all over. If you want, I can explain the physics equations, but that comes out to just a little under four g’s of deceleration, and a stop within about 63 feet.

Example 2: Now instead of bushes and weeds, let’s say it really wasn’t your day, and you hit something harder at 75 knots, undergoing a 10-g deceleration. That’s a dead stop in just under four tenths of a second, and in only about 25 feet. Believe it or not, if you’re belted in right, you have a good chance. No shoulder harness? Can you say reconstructive facial surgery? No? How about raw meatloaf?

NOTES TO LIVE BY: A little self-restraint can be good for you. If you’re one of the lucky ones with your own airplane, consider this an exercise in interior remodeling. If you’re in a flying club, petition your board of directors to make the change, and if you’re a renter, well… it may not be so easy… but you can always show them this.

Further reading:
FAA Aeromedical Education Division publication AM-400-91/2
FAA Aviation Safety Program publication FAA-P-8740-45