We practice like crazy for the nasty crosswind we know lies somewhere in our future and we're always working to avoid potential stall-spin situations, but we really don't do much training for getting caught under the clag. Even though the majority of en route accidents are weather-related, we really don't simulate being forced to fly under weather--or learn how to find our way out. Perhaps it's because we know that the safest course is to keep out of marginal weather in the first place--when it looks as if you're getting forced down, backtrack to the nearest airport, land, and wait it out.
Sometimes, however, stuff just happens and we find ourselves down there at 500 to 1,000 feet above ground level, wishing we were someplace else--almost anyplace else. Let's construct some training scenarios that are meant to build experience so that, if we should find ourselves where we don't want to be, we'll have some strategies to deal with the situation, rather than having to invent techniques as we go along.
A potential hazard that goes with being forced to fly outside of our comfort zone (in this case, below it) is the possibility that we'll panic and make a wrong decision. We can avoid that by training for this scenario, and the best training is to fly a few short cross-countries--preferably with a flight instructor--at altitudes much lower than we'd normally fly.
"Low" is defined by a combination of your personal comfort zone; the local topography (700 feet agl in Nebraska is a lot different than 700 feet agl in parts of Colorado); and the presence of cities, towers, and other things you'd just as soon avoid. The definition of "low" also can be altered by the visibility: 700 feet with 10 miles' visibility is an entirely different prospect than 700 feet and three miles.
How you react is critical: You have to monitor cloud trends. If you suspect that the clouds are getting lower, set yourself a minimum altitude, while at the same time keeping track of the weather--and airports or, if the ceiling is really tight, potential off-airport landing sites--behind you. While a one-eighty is usually the best way out of deteriorating weather, you could turn around to find that the weather has closed down behind you, too.
Use the radio to find out what's happening at local airports ahead and behind. (This would be a great task to delegate to a savvy passenger, if that's an option for you.) Flight service stations may be able to give you helpful info, but unicom frequencies or other pilots are a great source of real-time local information. And remember that when flying at lower altitudes, your radio communications may be much more limited than what you normally experience.
When you see the altimeter coming down to your preset minimum, immediately divert either to the airport you just passed that was clear, or to an alternate that you have already determined is open.
Let's define "low" as an altitude that is at the very bottom of your comfort zone but consistent with safe operations in the area in which you'll be flying. We're not advocating getting down and playing with trees and telephone poles.
When you get low, one of the first things you'll notice is that your view across the ground is different than from only a thousand feet higher. As the angle of view flattens out you can't see nearly as far around. One of the old bush pilot training axioms is that every route you fly regularly should be flown a number of times at minimum altitude just so you see how much different even familiar landmarks appear from that altitude.
With limited visibility, navigation--especially pilotage (flying by landmarks)--becomes more difficult. Of course, someone is going to say, "We can always tune in a VOR." One of the problems with being forced low is that the lower you get, the shorter the VOR's effective range becomes until that mode of navigation is useless. This is where the GPS is both a monstrous help and a monstrous danger.
The specter of getting lost when under the clouds is real, and it used to be one of the deterrents that kept us from pushing into marginal weather. When you're not exactly sure of your position, you will be very conservative with your weather-related decisions. Since the GPS always locates us exactly, it reduces one fear factor and may tempt us to fly deeper into weather that we know is not healthy for us. Remember those personal minimums we mentioned earlier. This is when you have to override your get-there-it-is and tell yourself that even though you know the airport is close, you're already at your minimums, and it's time to go to Plan B.
There's also the little problem of GPS reliability. It would not be a lot of fun to push farther below the gray stuff only to find that it's masking one of those areas where GPSs don't work so well. Worse yet, what do you do if you're uncomfortably low and the GPS batteries decide to die, or a sun storm drives your navigation hardware batty? Look at it this way--if you are dependent on a mechanical device to tell you where you are, and you have no fallback, what will happen if it fails?
The training scenario we're going to construct simulates being unexpectedly pushed down by weather and having to navigate our way to an alternate airport. One of the keys to this is that you won't be told what that alternate destination is until you're in the air on the way to someplace else. So, you have to do all of the diversion planning on the fly, so to speak--this is great practice for your practical test. Never conduct an exercise like this alone. Ask your flight instructor to pick a destination that is at least an hour away and is obscure enough that finding it will be a challenge.
OK, so you're flying along at the lowest altitude at which you're both comfortable and safe, according to local topographical conditions. Then your instructor tells you that the clouds have come down to your altitude--where will you go? He sticks the sectional chart in front of your nose. Now you're on your own.
First, you have to recognize that a couple of things will happen fairly quickly, because you're moving across the ground at about two miles a minute. So, the longer it takes to do your navigating, the less accurate it will be, because your starting point will change. To reduce that effect, take a look at the chart for an approximate direction to the new destination you've selected, and take up a new compass heading that points you in that general direction. Make sure the terrain allows you to turn safely in that direction. As you do this, place a pencil mark on the chart where you made that turn and note the time.
| Pinch the sectional between your location and the destination (far left); define the course line with your pencil (center). Roll the pencil from your course to the nearest VOR rose to get a magnetic heading (right). | ||
Immediately take the sectional and pinch it between your fingers at both your current position and the destination, then pull the chart across your thigh. That will put a crease between the two points, and this crease becomes your course line. You can tighten the crease by running your fingernails over it. Then take your pencil (you do fly with a pencil in your pocket, don't you?) and rub it along the crease, which produces an honest-to-goodness course line. (You can also draw the line with your plotter--it is handy, isn't it?)
Now you have a course line but don't know your exact magnetic heading. Don't worry about that. Just lay your pencil on the map parallel to your course and roll it until it lies across a VOR rose. That will give the course corrected for local variation, and all you have to do is apply the few degrees' difference that is indicated on the correction card under your compass to get an exact compass heading that, as yet, includes no wind correction. Make a guess how much wind there is, and from which direction, and crank a few degrees in that direction.
This shouldn't take more than 90 seconds, start to finish, so you now have a course line and the compass heading that's needed to fly that course line. Of course, we're low, so we can't see very far down the course line. We're pretending that we're in lousy weather, so we may not be able to see more than a couple miles ahead and can't fly visually from checkpoint to checkpoint. And, the destination may be so small that we could easily fly right over it and never know that it's there. We need an estimated time of arrival (ETA) so that we know when to start looking for the destination.
Remember that the moment we turned on course, we wrote down that time right on the sectional where we started. In a couple of minutes we're bound to see some sort of landmark that we can identify on the sectional, and we write the time next to that landmark. With a little mental calculation, we now know how long it took to fly that distance. We don't know exactly what that distance is, but--and this is important--we don't have to.
We're not interested in our speed. The only thing of importance is a time at which we should be arriving at our destination, and at any intermediate checkpoints that we want to identify. We can figure that out using the time it took us to fly from our turn point to our first landmark.
Let's say it took four minutes, 30 seconds to fly that distance. We lay our pencil on the course line with the tip of the pencil at the new landmark/checkpoint and put our thumbnail on the pencil where our turn point was (our starting point). So, that length of pencil represents 4.5 minutes of flying time. We put the pencil on the course line with our thumbnail on the new landmark where we noted our time, and make a mark at the pencil's tip on the course line ahead of us. Then move our pencil, with our thumb on it, up to that mark and make another mark. We segment the rest of the course into pieces with pencil marks that we know are 4.5 minutes apart. By counting those segments and multiplying, we know how many minutes it's going to take to get to our destination. Eight segments, for instance, is eight times 4.5 or 36 minutes.
If we want to get fancy, we can mark the progressive ETAs at each of the pencil marks on the course line ahead of us, which will give us ETAs to the more recognizable landmarks ahead, which will then allow us to check our progress. Ideally, because of the limited visibility, we'll find checkpoints as close together as possible, but don't pick subtle things on the sectional that you could have trouble identifying. Also, scan the course line ahead on the sectional for obstacles (mountains, towers, etc.) and draw bold circles around them so that you know exactly where they are and select an altitude that safely avoids them.
From that point on, it is basic dead reckoning but, because of the limited visibility, we don't have much margin for error. First, we're going to hold our compass heading as exactly as we can. When we reach a checkpoint, we want to cross it dead center; if we're off one way or the other, and we've been holding a steady compass heading, then the logical assumption is that our wind correction wasn't quite right and we increase or decrease it one degree and see how that correction works out on the next checkpoint. The name of this game is to develop an understanding of how important it is to be exact in both your navigating and your flying, as well as being more observant of landmarks when you're low. At even 1,000 feet agl, we can be off by a couple of miles and still see our destination, but that margin rapidly disappears as you decrease altitude.
So, the next time you're venturing out of the pattern, make it a lower-than-normal cross-country. Both you and your instructor will learn something along the way.
Budd Davisson is an aviation writer/photographer and magazine editor who has written approximately 2,200 articles and has flown more than 300 different types of aircraft. A CFI since 1967, he teaches about 30 hours a month in his Pitts S-2A Special. Visit his Web site.
Want to know more? Links to additional resources about the topics discussed in this article are available at AOPA Flight Training Online.
Related Articles
