Handling In-Flight Emergencies - Part 5

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Few people like to think about the unthinkable. Our local newspaper just reported that in the year 2028 a large asteroid may strike the Earth, delivering megatons of energy to our doorsteps. This isn't a comforting thought, but it is a good reason to consider buying that RV you've been thinking about. After all, it's hard to hit a moving target.

The unthinkable is the focus of this series on in-flight emergencies. Setting an airplane down in inhospitable terrain is, indeed, a very rare event. Yet, we can prepare for the event for no other purpose than finding comfort in the knowledge that we have a plan in case the unthinkable occurs. Here are a few additional thoughts to consider in case an engine fails over rugged terrain.

Occupant Restraining System

As you'll soon discover, I am a big fan of seat belts and shoulder harnesses. I wear them whenever I'm in anything that moves. And, if my bed had them, I'd wear them at night since I live in the earthquake capital of the world+California. Why the fanaticism?

Many years ago an FAA friend showed me pictures of several crashed airplanes and asked me to speculate about how the occupants faired after the impact. He slipped me a picture of a Belanca Viking that didn't look too badly damaged. I said, "Hmmm, no fatalities on this one." Wrong! The right seat and back seat passengers died. The pilot, who was wearing a seat belt and shoulder harness, lived. Then he showed me a picture of an A-36 Bonanza that was almost flat as a pancake, its cockpit nearly destroyed. I said, "No way anyone could survive that." Wrong again. Both pilot and passenger survived because they both wore seat belts and shoulder harnesses.

The fact is that your biggest ally in surviving a crash landing is the airplane's passenger restraining system. Here's what you'd order if you had your choice of a good restraining system.

First, you'd order a double shoulder harness (Figure 1) with a lower body restraining system (belts that wrap around the inside of your thighs). A lower body restraint keeps you from sinking and sliding under the lap belt during sudden stops. You'd also choose belt webbing at least .09 inch thick, preferably constructed from Dacron vs. Nylon (Nylon stretches a lot more under a given load).

Second, the strap over the shoulder should make an angle of approximately 25 degrees with the horizontal as shown in Figure 2. Angles less than 25 degrees may cause spinal compression as the pilot's body moves forward and under the shoulder harness. Strap angles greater than 25 degrees with the horizontal may not provide the restraint necessary during a high-G stop.

Third, the angle of the seat belt should be approximately 45 to 50 degrees as shown in Figure 2. Additionally, these belts should lie across your hips, not your upper thighs nor your lower abdomen. If the hips aren't restrained in a crash, your body could slide under the belt, causing abdominal or spinal injuries. This is the reason that inner thigh restraints are very helpful in a crash. Seat belts resting above the hips might not restrict the forward movement of your body in a crash.

Figure 3 will make you a real believer in shoulder harnesses. Column A identifies accidents where the cabin was distorted but remained intact (representing 68% [a total of 1,069 occupants] of the accidents studied). These accidents resulted in 210 occupants suffering serious injuries and 143 suffering fatal injuries. The FAA said that shoulder harnesses would have prevented all these serious and fatal injuries.

Column B identifies those accidents where the cabin was partially collapsed (representing 24% [a total of 379 occupants] of the accidents studied). These accidents resulted in 90 occupants suffering serious injuries and 155 suffering fatal injuries. According to FAA information, shoulder harnesses would have reduced these serious and fatal injuries by 50%.

Seat Position Before the Crash

Seating position is another important factor in crash survivability. As we discussed in Part 1 of this series, stopping distance is the key to preventing injuries. The typical cropduster has approximately eight to ten feet of distance between the pilot's seat and the tip of the airplane's nose. That's an extra eight to ten feet of distance in which to decelerate the airplane's occupants. If a pilot only needs 12.3 feet for a 9-G deceleration, then eight feet of crushable nose area give the pilot 65% of that distance.

Many light twins have similar distances between pilot seats and the tip of the airplane's nose. Smaller training airplanes, however, can have only four to six feet of distance between pilot seating positions and the airplane's nose. What does all this mean to you?

It means that you may gain a slight advantage in survivability by increasing the distance between you and the airplane's nose. You and your passengers would do this by moving your seats as far aft as is practical. In most smaller airplanes you can gain nearly a foot to a foot-and-a-half advantage in distance by sliding the seat back.

In some cases this is more practical for the front seat passenger than it is for the pilot. After all, the pilot must still fly the airplane. If the pilot is short, he or she needs to remain close enough to manipulate the flight controls. Taller pilots can easily slide the seats aft before impact (if they're not already against their aft stops).

Passengers should also place something protective over their face prior to impact. A jacket works well in these instances. This tends to be more difficult for the pilot to do since he or she still needs to fly the airplane. But, where possible, pilots should do the same prior to impact.

Gear Up or Down?

Whether the gear should be up or down during an emergency forced landing in inhospitable terrain has always been a point of contention among pilots. Detailed advice on whether the gear should be up or down is suspiciously absent from almost all Pilot Operating Handbooks (POH) that I've seen. In fact, most POH's state only the following in regards to gear extension during an emergency landing:

"Landing Gear ? up or down (depending on terrain)."

Huh? Could we be a little more vague about that?

The Navion owner's manual provides the most extensive advice I've ever seen written on the subject in any POH. It reads:

"If the landing area selected appears relatively smooth ... lower the landing gear. If there are any indications of stumps, ditches or rough or muddy ground, keep the gear up. There is less chance of injury in making a belly landing."

As you can see, this isn't very extensive advice on the subject. Nevertheless, it's the best there is (for this particular airplane). So, let's consider these points in gear use during an emergency landing.

First, if the surface is hard (dirt, sod, asphalt, concrete, etc.) it makes sense to land with the gear down. If the surface is soft enough to cause the wheels to catch, possibly flipping the airplane over, then land with the gear up. Surfaces like water, mud and swampland could easily cause the airplane's nose to dig in and flip the airplane if the gear were extended.

Second, consider the advantages of extended gear when forced to land in the tree tops. The landing gear becomes a breakable impact-absorbing structure which may help retard forward motion through branches. Additionally, depending on the type of gear, it may offer better deceleration in the vertical direction.

There are concerns, however, about crashing airplanes with the gear down. It's possible that the gear could tear into a fuel tank as it rips away during impact, leading to a fire. This is more of a concern for low-wing airplanes than it is for those with high wings. Also, during impact, the gear might enter the cabin and injure the passengers. Finally, on some airplanes, part of the gear lies directly underneath or ahead of the fuel tanks. Thus the gear may provide a barrier of sorts to minimize the chance of fuel tank puncture. How do you know if this is true for your airplane? You don't, unless you ask. Find a competent mechanic and ask him or her about the gear and fuel tank structure or call the airplane manufacturer for help with this information.

Whatever you learn or decide about gear-up or gear-down landings, you can take solace in a study done many years ago by the USAF Flight Safety Research Branch. This study indicated that, in any sort of terrain, forced landings in tricycle-geared airplanes are less likely to result in injuries or fatalities if the landing gear is down.

Landing Site Selection

Throughout this series we've assumed that our landing site is in unfavorable terrain. Mountainous areas, trees and boulder-strewn fields all qualify in this category. Of course, your job is to avoid those areas that diminish the chances of making a successful emergency landing. One way of avoiding these areas is by staying home and wedging yourself between two big mattresses. But what fun would that be? Therefore, let's examine a few more ideas regarding preferable places to land.

Figure 4 shows possible landing sites, their appearance from the air and their desirability for landing use. While this list is anything but complete, it does provide you with a start for assessing the desirability of a landing site. It's also possible that the only reasonable field in which to land is too short. What do you do then?

Sometimes it's preferable to attempt a landing in a confined area that's free of obstructions instead of attempting to land in an area with scattered obstacles. Once again, there are no hard and fast rules here. Each case must be assessed individually.

Approach the problem this way. The next time you land, make it a short field landing. Since runway lights are spaced at 200 foot intervals, make a rough estimate of your stopping distance while taking the headwind into account. In Cessna 172's, for example, it takes about 550 feet of ground roll to bring the airplane to a stop. To clear a 50 foot obstacle and stop, it takes a total distance of approximately 1,200 feet. These figures are typical for gross weight conditions at sea level.

Now compare that to the length of a football field, which is approximately 300 feet long. Football fields are rather common and are easily seen from the air. This gives you a good measure by which to estimate the length of a field while airborne. Ask yourself, "Could I get this airplane down and stopped in the length of a football field?" The answer is, "Yes, you can, as long as you have a few other tricks in your bag to work with."

The above mentioned short field distances are based on an approach speed of 30% to 40% above stall speed (the typical speed most POH's recommend for short field approaches). But who says that you must approach at 30% to 40% above stall speed when trying to get the airplane down in a confined space in an emergency?

I've known pilots to use values of 10% to 20% above stall speed for short field approaches. Of course, they have power if they need it and they are quite cognizant of operations on the back side of the power curve. Nevertheless, in an emergency, if you had to get an airplane down in a confined area, and you were skilled at airspeed control, it's perfectly reasonable to make an approach with a much lower short field approach speed. Remember, we're talking about an emergency here, not normal flight conditions. The lower approach speeds should dramatically decrease your obstacle clearance and landing roll distances.

Sometimes, it may be wise to force the airplane down onto the ground if a collision looks imminent. Considering this circumstance, raising the flaps on touchdown or even during the flare is another reasonable action. Perhaps you may even retract the gear after touching down as a deceleration aid.

Ground looping the airplane is another option if it's necessary to stop in a short distance. I am, however, always concerned about an airplane flipping inverted during a ground loop. As we discussed last week, an inverted airplane may present difficulty during egress. All these variables must be taken into account in an emergency.

Let's consider one more point on selecting landing sites. I've heard pilots talk about forcing an airplane down in a lake in mountainous terrain where there are no other reasonable landing sites available. We will consider water ditching in a future article but, for now, understand that landing in water isn't much softer than landing on solid ground. Anyone who's done a belly flop off a diving board knows this. If you forced an airplane down into a small lake, and survived, ask yourself how long you'd live in the typical freezing water of high mountain lakes. Hypothermia is a killer.

Your biggest concern with forcing an airplane down in a small lake vs. a similar size land mass isn't with hypothermia. Rather, you are mainly concerned with being knocked unconscious by the impact and drowning. As you'll see in a future article, most airplanes don't float for long. If you're knocked unconscious during a water landing, your chances of survival are very poor (remember, we're talking about forcing an airplane into a short body of water). On the other hand, and relatively speaking, being knocked unconscious on land isn't all that bad as long as there is no postcrash fire.

The odds that you'll ever need to apply any of the information contained in this series of articles are miniscule. I present this information to you because it's simply comforting to know that there are answers to some of the very difficult problems on which we speculate when sitting around the flight school. I wish I could lead you to more literature on how to handle emergency landings in inhospitable terrain. Unfortunately, there isn't a lot of information available on this subject, and that was written by Mick Wilson. I've listed it below.

• Mick Wilson, a retired FAA inspector and crash researcher has a book titled "How to Crash an Airplane." Information can be found by e-mailing Mick at: [email protected].
• The following NTSB Report Number - AAS-72-03 , Adopted on 04/05/1972. Order NTIS Report Number - PB-209836 . Title: Emergency Landing Techniques in Small General Aviation Fixed Wing Aircraft is a very informative report. You can locate this information at: http://www.ntsb.gov/Publictn/A_Stu.htm

This is the end of the five part series on handling the emergency landing in inhospitable terrain. Look for another series of articles on in-flight emergencies which will cover topics such as electrical and petroleum based in-flight fires, gear-up landings, flight control failure, flutter, propeller fracture and much more. Remember, the idea isn't to be scared; it's to be prepared.

For more information on this subject, see "The Long Wait: What To Do Until Help Arrives."