Vintage Instructor THE
BY Steve Krog, CFI
Some rules of thumb for vintage pilots On June 1, 2012, the FAA enacted a new set of guidelines to be used by flight examiners when administering an oral/ flight test for a new or an advanced rating. The new guidelines are quite different than when most of us first took our private or commercial pilot checkrides. Remember having a two-way discussion during the oral portion of the test between you and the examiner, where he or she asked you a number of questions about regulations, airspace, and the airplane you were intending to fly? Most everything was done in a friendly question-and-answer format. The new guidelines that the examiner must now abide by involve “scenario” based situations. For those of you old enough to remember doing what we called “story” problems in grade school math, the new testing format follows a similar path. Here’s an example: Your best friend has asked you to fly him to a location about 200 miles away where his elderly mother has taken ill. You’ll need to leave at sunrise tomorrow and return the same day as your friend can only get one day off work. The nearest airport to his sickly mother is a private turf strip about 2,000 feet long. What actions or steps will you take to make a safe flight? That’s simple, you might be thinking. A check on the weather outlook for the next day indicates that it will be CAVU (ceiling and visibility unrestricted), surface winds light and variable, but the temperature will be a “warm” 95°F. It should be a beautiful day for the round-trip flight. Later that evening, after looking over your sectional maps, a very small stomach knot has developed. You call your friend back and ask what he knows about the private turf strip. His response is, “Don’t worry about it. The old fellow who owns the strip always keeps it mowed and flies from the strip on a regular basis.” All seems to be in order and you settle in for a good night’s sleep in preparation for the trip. Early the next morning you meet your friend at the hangar. He’s anxious to get going, checking his watch every minute or so while you attempt to do a thorough preflight inspection. Your friend’s impatience wears on you, so rather than getting an updated briefing for your route of flight, you decide to get airborne. After all, the forecast was for perfect weather all day. Once in the air and level at a comfortable, smooth altitude, both you and your friend relax and settle back for
30 SEPTEMBER 2012
a good flight. Twenty minutes into your one and one-half hour planned flight you notice the ammeter is not showing a charge. In fact, it seems to be indicating a slight discharge. “No problem,” you think to yourself. Just shut all electrical items off for now and check things out once on the ground at your destination. It’s a simple flight and can easily be flown using pilotage only. Ten minutes later the horizon ahead of you seems to be disappearing, and it looks awfully dark beyond. Five minutes later you have determined that a line of thunderstorms has developed, and you’ll have to deviate 30-40 miles off your route of flight in order to avoid the impending thunderstorm. And you wonder, “Where did that come from? It was supposed to be clear all day!” Ah, the briefer did say there was a near stationary cold front well beyond your destination and shouldn’t be a problem unless it begins to move. Apparently, it has begun to move, and you scramble around looking at your map trying to pick out landmarks that will help you find your way around the storm. Twenty-five more minutes later you’ve been able to get around the end of the line of storms and begin to turn back on a course to your destination. However, the air is now quite rough, and your passenger indicates that he might need to cough up his breakfast real soon. Quick, you know that you have a sick sack or two in the plane, but where did they get placed? An uneasy two or three minutes later, a sick sack has been located and your passenger has buried his face in it. So far, so good. It is only another 40 minutes, more or less, to your destination. Then your passenger decides to fill the sick sack with his early morning breakfast of scrambled eggs, bacon, toast, juice, and coffee. The stench rapidly fills the cockpit, and your stomach begins to churn. Fresh air vents are opened to the maximum, and you begin breathing through your mouth to prevent the smell from entering your nose and further churning your stomach. Finally, after what seems like several uncomfortable hours but has only been about 45 minutes, the private airstrip comes into view. While reducing power and beginning a slow descent, you notice that every square inch of the earth’s surface seems to be wet with large water puddles standing everywhere.
You begin wondering what condition the private turf strip might be in with all of the visible standing water. What if there is water on the strip? How soft will it be? You know you can easily land in 2,000 feet, but the runway surface may be cause for making something other than a normal approach and landing. With several long, deep breaths to regain your composure and hide the uncertainty and growing stomach knot, you decide to make one low pass down the runway to look it over before landing. Much to your relief the runway looks dry enough to land on, but two new problems have arisen. It appears the grass is somewhat long, and there is a big flatbed wagon filled with hay bales sitting on one end. Mind racing, how much distance is needed to land this airplane on wet turf? The taller grass should slow the airplane down, but then there is the wagonload of hay bales to contend with. The remains of what once was a windsock favor a landing over the wagon, but then you’d have to make an obstacle short-field landing on a turf strip of unknown condition. While making the go-around after inspecting the runway, you begin trying to recall some of the performance factors for the airplane. Let’s see now, a normal landing with little or no wind takes about 1,000 feet, and the tall grass will slow the plane down quite a bit, won’t it? A downwind landing will also add to the landing distance. Now is not the time to think about what should have been done in advance of the flight! Rather, it’s time to calm down and think through the situation, even though your passenger is getting fidgety and begins asking a lot of foolish questions. Turning final for the planned long, low, and slow downwind approach, all seems to be going good until you spot the barbwire fence on the approach end of the runway. Adding a little power to clear the fence has caused an increase of 5 mph airspeed. Once clear of the fence, power is reduced to idle, and the airplane floats before touching down. Hard application on the brake pedals doesn’t help, and the airplane now wants to skid to the right side of the runway. Keeping the wing out of the tall corn, you firmly tap and release the brakes. The hay wagon looms larger in the windshield by the second, but finally the airplane comes to a stop with 100 feet to spare. After your passenger deplanes and leaves to visit his ill mother, you have time to take several more deep breaths and think about all of the situations you’ve encountered in the past two hours—and how they could have been prevented! First, an updated weather briefing is a must. Conditions significantly changed in the 12 hours between your briefing and departure. Second, it would have been wise to contact the airstrip owner and learn of the surface conditions. Had the owner known you were coming, he may well have cut the grass and moved the hay wagon. Third, when flying to a short airstrip, it would be very
wise to review the performance charts for your airplane. In the case of vintage airplanes, this precise information may not be published. However, there are some very simple “rules of thumb” that all pilots should know. Landing on wet turf airstrips, even if the grass is tall (10 inches), will increase the landing distance by up to 30 percent. Landing with a tail wind of 10 percent of liftoff speed will increase the landing distance by 20 percent. An easier, more general way to remember this is to add 20 percent to the landing distance for every 5 mph of tail wind. For every 1 mph above the recommended landing speed, add 100 feet to the landing distance. Using the above described scenario, here is what the pilot should have calculated: If liftoff speed is 60 mph and the tail wind is 6 mph, and normal landing distance is 1,200 feet, add at least another 240 feet for the landing distance. The wet grass will add another 30 percent to the calculated landing distance, so add another 360 feet. Adding a bit of power to clear the fence added 5 mph to the approach speed, which converts to an additional 500 feet of needed runway. 1,000 feet + 200 feet + 300 feet + 500 feet = 2,000 feet The flight described here ended uneventfully, thankfully. However, the pilot in this example may well have opted to land somewhere else, preventing a lot of unneeded anxiety.
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