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09/02 - Forced Landing During Cruise Flight

By Steve Krog

Everything is operating smoothly while on a cross-country pleasure flight. You and your passenger have been lulled into a near state of euphoria watching the spectacular landscape glide by underneath you. The beautiful colors and patchwork farm fields surrounded by trees and small streams causes one to feel as if you’re flying through paradise. Suddenly, the sound of the engine is deafening quiet and every nerve ending snaps to attention. What happened? Why did the engine quit?

Teaching a student pilot how to deal with potential emergency situations is an FAA requirement. When the day arrives for your sport pilot or private pilot checkride, your examiner will have you demonstrate your learned emergency procedures during a simulated forced landing. It is nothing to fear. Rather, think of forced landing training as safety training. You were required to receive safety training to obtain your driver’s license, and if you ride a motorcycle, you also participated in a rider safety class. Learning to fly is no different. We practice procedures for emergency situations and hope that we never ever have to use them.

As discussed in the last newsletter, engine failures are extremely rare, but if and when they do occur, they are frequently due to the pilot’s lack of continually “thinking ahead of the airplane.”

The two primary causes of engine power loss are fuel starvation or carburetor ice, both controlled by the pilot. Switching fuel tanks will usually cure the quiet engine after allowing a few seconds for the fresh supply of fuel to reach the carburetor. Carburetor ice will generally make its presence known through gradual loss of RPMs followed by a rough running engine. Proper application of carburetor heat will most often cure this situation. Throughout the course of your flight training your flight instructor will work with you in simulating both of these potential forced landing situations.

Should a true system or engine malfunction occur resulting in a potential forced landing, there are procedures to follow and your flight instructor will teach them to you. Let’s assume you are cruising on a westerly heading at 6,500 feet MSL (5,000 feel AGL), and you are dealing with light and variable winds. The engine develops a malfunction and begins running rough. What are your options and what are you going to do?

A statement in an aviation article I read recently said, “There’s often a significant difference between how people think they’ll act and how they actually behave in a given setting.” This statement is quite appropriate when working with students and teaching the procedures for forced landings. Even though you and your instructor have talked at length about forced landings and the procedures for the same prior to your next training flight, the first time he or she slides the throttle to the idle position and says, “Simulated forced landing. What are you going to do?,” your mind races and you can’t remember a single thing previously discussed. This reaction is quite common. Don’t be alarmed. Remember, you have a flight instructor sitting next to you.

First and foremost continue flying the airplane. The airplane didn’t quit flying just because there was a loss of power. Again, “think ahead of the airplane.” Lower the nose to establish the best glide speed attitude for the airplane you are flying. The airplane’s Pilot Operating Handbook is the source for this information. In this example, again use 60 mph. Now that you are in full control of the airplane, several things need to be done simultaneously which include:

1. Continue flying the airplane.
2. Establish a 60 mph best glide speed.
3. Apply carburetor heat.
4. Assure the mixture is in the “Rich” position if you have leaned the mixture.
5. Look over the fields and terrain below and around you, select a field where you will make your forced landing, and turn the airplane toward the field.
6. Change fuel tanks.
7. Move the throttle from cruise power to idle and back to cruise power.
8. Check the magnetos by changing the position from ‘Both’ to ‘Left’ and then ‘Right.’ In so doing, a bad magneto can be isolated if it is the cause for the rough running engine.
9. If unable to get the engine to run smoothly and develop power after trying steps 3 through 8, – “thinking ahead of the airplane” – we have two possible options.

Option A: is the engine developing enough power that when combined with the altitude available (5,000 feet AGL), will allow a safe slow decent to a nearby airport?

Option B: if unable to reach a nearby airport, then fully commit to making the forced landing in the pre-selected field.

Let’s briefly look at the option “A” scenario. The engine is running rough but is still developing some power. Scanning the area, we locate a small airport that is approximately five (5) miles away and we have 5,000 feet of altitude.

Without training, the most common student error is to look for a field near the airplane. However, by “thinking ahead of the airplane,” we have another option—the airport five miles away.

How can this be done? If we’ve done our homework, we know that the airplane we are flying has an 8 to 1 glide ratio with no power being developed. This means that for every foot of altitude we descend, we move eight feet forward. The airport is approximately five miles away or 26,400 feet from our present position (5,280 x 5). Our present altitude is 5,000 feet above the ground. Under a no-wind condition we should be able to glide approximately 40,000 feet forward (5,000 x 8), or approximately seven and one-half miles until we reach ground level while gliding at 60 mph. But in this example the airplane is still developing some power, which will extend the glide even further. By “thinking ahead of the airplane” as well as knowing the limitations of the airplane we are flying, we can easily make our forced landing at the airport rather than in a hay meadow five miles from the airport.

Now let’s explore option B. We’re flying the same airplane at 5,000 feet AGL when we experience an engine malfunction. Immediately, we’ll move through steps one through nine above and determine that we have to make an “off-field” forced landing.

It’s easy to jump to conclusions at this point and make a hasty decision that proves wrong. Take a deep breath and continue to fly the airplane. Then begin making the selection of a field in which to land.

Field Selection

While rapidly scanning the area for a suitable field in which to land, don’t forget to look down. Oftentimes students, when practicing simulated forced landings, will select a field a mile or two away from their present position and pass up a very good field immediately below them.

Ideally, select a field that is relatively level, free of obstructions and lengthy enough to get the airplane safely on the ground and stopped. Depending on the terrain though, an ideal field may not be an option.

Much has been written about field selection when dealing with a forced landing. Rather than go into great detail in this article, I strongly recommend that you and your flight instructor discuss the airport surroundings and off field options for the area where you are doing your flight training.

Next, determine surface wind direction so the landing can be made into the wind. This is not always possible, however, but desirable. Perhaps the field selected is more perpendicular to the surface wind direction.

Obstructions

When selecting a field for an off field landing, don’t forget to look for obstructions that aren’t readily apparent. An electrical power line across the approach end of the selected field is a good example. Or there might be a tall stand of trees at the end. Adequate altitude will be needed to clear the trees.

Approach

While continuing the descent toward the selected field, consider your rate of descent (altitude loss). If it appears that there is excess altitude, fly a descending 360-degree shallow bank turn over the selected field. For most general aviation training aircraft, figure that 1,000 feet of altitude can be lost during the 360-degree turn. Then roll out of the turn and fly parallel to the field just like flying a down wind leg at the airport. Continue to closely monitor your altitude. Adjust your approach by turning toward the field if it appears you might not have enough altitude to reach the field. Remember, this is a simulated forced landing and as pilot in command you may alter the approach in any safe manner to comfortable reach the field.

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Landing

After using your judgment to adjust your altitude for the approach, it’s time to set up for the landing. For this simulated forced landing, let’s assume that we do have trees at the approach end of the selected field. This will necessitate what is called an “obstacle” landing. Turn on to the final approach and align the airplane with the field. If it appears that there is excessive altitude, “slip” the airplane to lose some of the excess and continue your 60 mph approach. Once you’ve determined that you can safely clear the trees, again put the airplane into a slip to lose any remaining excess altitude. Take the airplane out of the slip, level, flare, and touch down just as if you were making the landing at the airport.

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During flight training your instructor will allow you to continue to set up for a forced landing until it is apparent that you would have easily and safely made the landing. At that time he or she will have you add full power, climb, and continue your flight maneuvers.

NOTE: If making a true forced landing, fuel, magnetos, and the master switch should be shut off while on short final.

The examples presented in this article should provide you with several training tips for safe flying. If you know your airplane and “think ahead of the airplane,” your options for a safe conclusion to an emergency or forced landing situation are significantly greater.

Editor’s Note: Examples presented are generalized for primary instruction purposes. Winds, aircraft weight, glide ratio, terrain, and flap use, if available, will influence the choices available when making or practicing forced landings. Discuss all emergency procedures with your flight instructor.

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