Forced Landings By Robert T. Smith, EAA 1685 194 South Cobb Dr., Mariett- , "•>. Key. So you must plan your approach to arrive at the High Key, flying in the same direction you will be on your final approach. When you arrive at High Key, you should have a specific minimum altitude. Thus, you must are your instructor's well-drilled forced landing procedplan your approach to the field to be at High Key point, ures are still fresh in your mind. But suppose you haven't and at High Key altitude. For a lightplane trainer, this had a dual ride in five years? How current are you on altitude is about 1,200 feet, as shown in our example. forced landing procedures? Remember, this is TERRAIN CLEARANCE ALTITUDE, If you're like me, it's been several years since you and NOT altitude above sea level. Be sure to check your had someone pull the throttle, and call "forced landing!" map for the terrain elevation BEFORE you arrive at High The other day I got to wondering what I would do. ModKey. I would suggest noting terrain elevations along ern engines aren't likely to quit running suddenly, but your flight path prior to take-off rather than waiting what about carburetor ice, empty fuel tanks? It CAN hapuntil the engine quits! pen—it DOES happen! From High Key we start a turn, right or left, with a Some months ago, I was instructing Air Force prishallow bank. What we want to do is turn 180 degrees mary students, and we used what I think is a fine idea to the Low Key position which is just opposite our infor forced landings. It was called simply the "Forced tended touchdown point, and at an altitude of about 900 Landing Pattern," and essentially it is a power-off 360 feet for thz typical trainer. You should be about as far degree, overhead approach. However, it has some variafrom the touchdown point as you'd be from the runway tions to enhance its usefulness over just a simple, poweron a normal traffic pattern downwind leg. You must vary off, 360 approach. But, before we go into this standard your bank to arrive over Low Key at the proper position Forced Landing Pattern, let us remember that engine failand altitude. From Low Key on, it's just a 180 degree ures can happen from altitudes of one foot to several side approach. thousand feet. Naturally, with minimum altitude, the Wind will naturally play an important part in this pilot has less choice of what to do, and when the engine pattern. If the wind is strong, your bank will be steeper quits on take-off, there simply is NOTHING to do but when turning into the wind. If you have a cross wind, land straight ahead, maneuvering just enough to avoid you'll know this because it will tend to blow you away obstacles. from, or toward the proper Low Key position. However, Let us discuss the Forced Landing Pattern for a typirather than trying to worry about what direction and cal two-seat light trainer, and then we'll discuss how you velocity the wind is, simply vary your bank as necessary can modify this pattern for the airplane you fly. to keep your pattern where it should be. You should The Forced Landing Pattern is a 360 degree, overrealize that a strong wind blowing straight "down the head approach as shown in Fig. 1. The idea is to maneuver runway" will tend to whisk you downwind at a great rate the airplane over the field, and directly above the touchwhile you're going from High to Low Key, but will be down spot on a heading into the wind. At a point where strongly against you from there in to the touchdown. the airplane is directly above, or slightly off to one side This will mean a shallow bank from High to Low Key, of the intended touchdown spot, the airplane is at High and a steeper bank from Low to Base Key, our next "check point" in this HIGH KEY Forced Landing Pattern. FLIGHT PATH Base Key is 90 degrees of turn away from Low Key with 90 degrees of turn left to line up on final approach. The Base Key altitude of 600 feet will hold good for most light ships, but should be higher for heavier, or faster ones. YOU MAY BE SLIGHTLY RIGHT OR LEFT OF From Base Key on we'll make TOUCHDOWN AT HIGH KEY minor, slight variations in our angle of bank in order to vary our ground track so that we will make the field START OF FINAL APPROACH without overshooting, or undershootWINGS LEVEL ing. If you're a LITTLE BIT HIGH, you can slip, if you're a LITTLE BIT LOW . . . well, you're a LITTLE BIT SHORT! This brings up the point, \ , which is always well taken, that your "intended" touchdown p o i n t should be about midway down the GROUND TRACK field. Then, a slight undershoot will still let you land ON the field, which is the desired final result.

AVE YOU ever wondered what you would do if the H engine suddenly quit? If you've just learned to fly, or just recently obtained your private ticket, chances

1

Fig. 1

Standard Forced Landing Pattern

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FORCED LANDINGS . . . (Continued from preceding page)

You should be lined up, wings level, on the final approach at a MINIMUM—AN ABSOLUTE MINIMUM—altitude of 300 feet. If you've got a heavy or fast ship, you might make this 400 feet, or higher, but we used 300 feet in the jet-powered T-37, and it works out fine and dandy. Let's assume you have a ship whose altitude should be those given in our example Forced Landing Pattern. What happens if we pick a field right under us, and we have 6,000 feet? Nothing. Simply determine the wind direction, and start doing 360 degree turns over the field noting the altitude loss per turn. If you start at 6,000, and find yourself losing 1,000 feet per turn, you know that you'll arrive over High Key at 1,000 feet instead of the 1,200 you want. Therefore, during the descent from 6,000, you should adjust your 360 turn? to give you around 800 feet per minute for one turn, or make a wide 360 in which you lose 1,800 feet. Then, you'll find yourself at an altitude that will allow you to lose 1,000 feet per turn, and arrive at 1,200 feet at High Key. If you start at 5,000 feet (knowing you lose 1,000 feet per turn), and make one 360 real tight, you should arrive back over the field at 4,200, then you can go back to losing 1,000 feet per turn, and eventually you'll be at 1,200. Or, you could make a real wide turn, and lose 1,800 feet, arriving back over the field at 3,200 feet. Either way, you put yourself at an altitude that will enable you to lose the amount you will lose in a steady 360 turn so that you'll arrive over High Key with 1,200 feet. The important thing is to get this ironed out as early as possible. It might even be a good idea to take your ship up, and set up a normal power-off (engine at idle) glide, then establish a 20 degree banked turn, and note the altitude loss per 360 turn. Then, should a real forced landing come along, you'll know in advance how much altitude you lose in a 360 turn with 20 degrees of bank. You would also know that turning steeper would mean less altitude loss in a 360 while a shallower bank would mean more altitude loss in one 360 turn. Knowing this in advance would make your forced landing planning easier. What happens if you arrive at High Key with 200 feet of extra altitude? Obviously you can't make a 360 to lose that 200 feet, and just as obviously, if you follow the pattern to the letter you will be 200 feet high when you should be touching down. So, with 200 feet of extra

FLIGHT PATH

altitude at High Key, you merely fly a slightly wider pattern than that shown in the example. Or you swing a little wide from High to Low Key, and lose the 200 feet there. In a practical sense it is a good idea to know altitude LIMITS at the various Key positions, as it is difficult to hit the correct altitude right on the money. For a light airplane a figure of plus or minus 100 feet would be okay. If you are high, make a slightly wider pattern; if low, make a slightly tighter pattern, but in NO case should the "wings level" final approach altitude be compromised. This altitude is established for reasons of safety, and to give you a stabilized final approach which will better assure a safe touchdown. Your survival chances are greatly increased if you can make a normal final approach at normal speed, and make a normal touchdown. This will work even in extremely rough terrain, as the record clearly shows. Trying to make turns under SCO feet is cutting your survival chances to the bone. This entire Forced Landing Pattern is based on maintaining a normal glide throughout the pattern. Excellent comment on this subject is found in CAA Technical Manual 106 (The Pilot Instruction Manual). The pattern will work only as well as the normal glide is maintained. If you practice maintaining a certain glide air speed, you must remember to use that same air speed in an actual emergency. Allowing the air speed to vary introduces an error of unknown, and unpredictable magnitude, and completely ruins any other attempts to make the field. Aircraft control, and air speed control are the two prime factors if you are to have a successful forced landing. The final approach should be at your normal final approach speed, and if it is different from the speed you maintain prior to final, you should practice your Forced Landing Pattern using this speed, and changing it at the same point each time. We used 125 knots in the Forced Landing Pattern with the T-37, and changed it to 110 knots on the final. You might do the same thing in your ship. Consult your flight manual, and follow its suggestions. You can make very slight turns on the final to avoid obstacles, but keep the bank shallow, and maintain your speed. If you're landing on a field with trees, aim between two of them. You'll lose the wings, but that's better than losing your head! It will also slow you down, and better your chances for survival. Make the flare and touchdown normal. On soft ground hold it off as long as possible so your touchdown speed will be the slowest possible speed. NEVER try to "put it on" before the ship is ready HIGH KEY to land itself. Hold the wheel or stick well back as you touch, and bring it smoothly all the way back as you contact the ground. Don't let it go further forward until you are 1200 FT stopped. This will prevent your nose from digging in. Have your seat belt fastened firmly, and remember that a shoulder harness will greatly increase your chances of coming through with no injuries, or minor injuries. About the best support I can give to the shoul-

I

der harness is that it's found in ALL

military ships. Young Air Force pilots think "safety-belt-and-shouldorharness" is one word! They keep both

START N

300 FT — WINGS LEVEL!

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SEPTEMBER 1963

GROUND TRACK

fastened all the time.

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