Saturday, March 24, 2018

VFR Survival


This Section is for my comments on the joyous art of flying. I am not a professional pilot, nor do I have thousands of hours. But that does not make my opinions and reflections worthless. I have been around a long time and you don't get old by being stupid or not learning from your own mistakes andusing the accumulated wisdom of those around you. So take these "gems" as being worth what you paid for them.
 
VFR Survival
 
The mental game

The longer I muck around in the world of pilots and aviation, the more I see what seems to be an excess of anal retentiveness. An absolute insistence on doing everything by or according to a set of specific numbers. "Hold altitude +/- 50 feet", "Track VOR within a needle width", "Stay 1000' away from clouds", "do this to this standard", "reduce RPM to 1653" etc.. Isn't the point of being a private pilot to have fun? I have already stated my feelings about keeping ETA/ATA on cross country to within seconds and calculating fuel burn to tenths of a gallon. Figuring taxi time and climb time and descent time into the equation is ridiculous (to me). If you need to be that close, give yourself an extra 10 minutes and throw in an extra 10 gallons.


Now we delve into flying in less than perfect weather. If you are going to fly, you can't always have CAVU. If you intend to make longer cross country's or multi day trips, you need to accept that you will sometimes have to fly in conditions that are less than perfect, often down to what FSS will call "marginal VFR", and occasionally "VFR not recommended".


There is a line between being foolhardy and taking a measured risk. You wouldn't dream of not driving to work simply because it was raining and the roads were wet even though the risks are higher. You probably wouldn't postpone a trip to the movies or dinner out for that reason either. Change the rain to snow, and the rationale gets a little different. Depending on the distance to work, the types of roads to traverse and the amount of snow, you might go. You would almost surely cancel the movie.


The same reasoning is true of flying. It doesn't matter what part of the country you fly in, the weather will not always be perfect. You have to weigh the desire to go against the potential problems presented by the weather.


Personal minimums

I see a great deal of discussion on making go-no-go decisions based on fixed standards, normally referred to as personal minimums. If you do this, you will either limit your flying to a set of standards which will keep you on the ground until you lose interest, or be so loose that you will become a VFR into IMC statistic. Your "minimums" need to take the purpose of the flight into consideration.
If your intent is a couple of T&Gs, then 12-1500' ceiling and 5 miles visibility is acceptable. If you are going to make a <50 mile hamburger run, you probably want a little more ceiling, but if you have flown that route before, the visibility is probably acceptable. If it is to a new place, you might want a little more visibility. In other words, the "minimums" change with the requirements of the intended flight.
I don't like doing T&Gs in high or gusty winds, especially crosswinds. To me, T&G practice is to reassert the correct sight pictures for consistent approach and landings. You can't get the groove in those conditions. On the other hand, high or gusty winds are only an inconvenience on a long cross country.


Consequently, my personal minimums are strictly trip based. But even there, the minimums are flexible. For a one way cross country, I will accept lower conditions at departure provided that enroute and destination conditions are good. The reverse is not true, as I don't wish to get there and find conditions worse than I was aware of at takeoff.


Learning the weather

You should know from history and personal experience the normal patterns of weather movement for your area. The examples I will use assume DFW as the center of my area. The prevailing winds are from the south. If they have an easterly component, they will bring increasing humidity from the Gulf along with decreased visibility and potential convective activity in warmer temperatures. A westerly component will be dryer, increasing visibility and increasing temperature. Generally, a "dry line" will dangle across west Texas from eastern Colorado. As it swings like a rope, the swings towards our area will bring increasing winds and if the humidity climbs, it will also bring clouds.
Generally, weather here moves from NW to SE. Lines of convective activity move along the weather from SW to NE. If the weather maker is tropical in nature, all this shifts 90 to 180 degrees clockwise, coming from an easterly direction.


These same patterns hold for much of the south with the pattern of non-tropical weather shifting from NW to more westerly as you get further east.


Beyond historical patterns, learn to "read" the radar and satellite loops. You should have learned the short definitions of high and low pressure systems in ground school. Go beyond that knowledge and really look at them and their effect on weather patterns. That is why I go for the loops rather than the static pictures. Look at either on a large (300 mile) scale and you should be able to recognize the low circulations that bring rain on either the radar or satellite loops.
The DTN, or whatever, at the FBO does you no good in the evening after you have checked into the local inn. The Weather Channel is nice, but seldom shows radar images for more than a few seconds. A satellite image is even more rare. The "local on the 8s" is especially spotty in less metropolitan areas. Local news at 11, often will have even less information available. The now obligatory 5 day forecast that gives high, low and a pictorial representation of cloud/sun doesn't contain the kind of information that is useful to pilots. So it becomes imperative that you understand on day 1 what the probable weather will be on day 2 in the area you will be on day 2.


You also need to have an idea what the weather might be on the day(s) you will be returning.


I have found that accuweather has a reasonably good hourly forecast up to 5 days out, and you can give it a location. This allows you to see what the weather might be at places along your route at the time you will pass through that area.

Planning

Why make this flight?


Much has been said about the unholy twins get-thereitis and get-homeitis. They take a bad rap that is not wholly deserved. It is very easy to read about someone who wuz got by weather and assign blame to one of those twins. But we see people got by rain on there way home from work and think nothing of it.
You want to fly there and back? You have already made the decision to go. All that remains is weighing the reasons not to go. The plane has a problem, the room rates for an overnight, etc may all keep you from going. These are black/white decisions, but the weather is a different animal. It can range from no factor to a concern to a problem to an absolute deal breaker. If the reason to go is good, then the first 2 levels fall in the category of driving to the movie in the rain. The third level requires a go reason on the level of driving to work in snow or ice.

Weighing the reason to go this way moves getting home higher on the tolerance scale than getting there. In other words, you are probably willing to accept a higher risk to get home than you are to leave. You also have more and better options before you leave home.

Pre-flight planning

Longer trips, more than a Saturday hamburger run, need to be planned well in advance. This planning needs to include a careful surveillance of the weather from several days in advance. Try to look beyond the 5 day forecast screens of most weather forecasts. Look for radar and satellite pictures that cover the entire proposed route.

With all of this in mind, watch the patterns for the week before the trip. If the trip is not date sensitive, decide on the best day no more than 36 hours in advance. An example is our trip to Amarillo for the Texas performance in Palo Duro. We moved that one around for a week, waiting for a 3 day period that looked good. We left in clearing weather and had excellent weather for the remainder of the 3 days. If the trip is date sensitive like our reunion trips, try to have a day on both ends when you don't have to be at work. This would allow you to leave early and stay late if the weather doesn't like the selected dates.

The idea of leaving an extra day on each end brings us to the longer trips. If you have 2 days going, and 2 days returning, you are going to have limited weather information from the time you leave home until you return. Here is where understanding the weather patterns becomes more necessary.

The Flight Service weather briefing

Don't leave home (or the airport) without it. If the weather along your route is not going to be CAVU, pray that you will get a briefer who will work with you. I have called FSS at 9:00 for a 10:00 departure and had the briefer say that my destination was IFR only, end of conversation. I don't care that it is IFR only, NOW, I want to know what it will be at noon when I get there.

You should have already looked at an animated satellite picture, an animated radar picture, TAFs from all stations near your route and METARs from every station along your route. The METAR picture should be from a cone extending from your point of departure to your destination and expanding on the side where the weather is coming from. Example: the flight is from Dallas to Fort Smith, AR. The weather is moving SSE. Checking only the direct route, would be Durant, Hugo, Kerr and FSM. But since the weather is moving SSE, also check McAlester, Muskogee, and Salisaw. These are all on the north side of your course line and will tell you what may be moving into your path.

Pay particular attention to the temperature-dew point spreads. There is a complex (for the math challenged of you) formula for calculating the cloud base from this spread. But the formula requires Fahrenheit and the spread is given in Centigrade in the METAR. Suffice it to say that each 2 degrees Centigrade of spread will give you 1000' of ceiling. This is off on the pessimistic side, it will be slightly more. But it will give you a minimum to expect.

If you have all this information and it still leaves the decision in doubt when you call FSS, you need only those things that the briefer has that you don't. You also have an idea what the briefer is going to tell you along with the airmets and sigmets. You can see that your destination is socked in right now, but your analysis indicates that it should be clearing and the briefer can tell you when the airmet expires.

Also be aware of the definitions that FSS uses. "IFR only" is less than 500'. "Marginal VFR" is anything from 500 to 5000'. You only need 1500-2000 AGL. That is 1500 scattered and clearing, 2000 broken and clearing, 2500+ if overcast. And these numbers depend on the temperature dew point spread.

If the spread is 5 degrees now and the temperature is forecast to climb another 15 degrees, that spread will widen unless there are clouds or high humidity air moving in along your route.

But finally, and most important, always know that the weather is better ahead of you than it is behind. Don't take off in poor conditions unless you know that the weather is better enroute. Know that the weather at the destination and good and expected to remain good or at least expected to improve to good well before you get there.


The decision

When I get into my plane at the home drome, it has been at least 30 minutes since I have had any exposure to official weather. T31 has no FBO, no public phone and no AWOS. But I use the drive there to visually check the local conditions against what I have learned. Look at the sky for a full 360 from everyplace you can. At the intersection of Custer and McDermott, the water tower just south of the runway is exactly five miles away and it stands alone against the horizon. This is the final visibility check. Just north of highway 121, is a tower that is 800' AGL If I can't see the water tower or the top of the communications tower, there ain't no way I am going to get the plane out of the hangar. If the visibility is 5 miles and the ceilings appear as forecast, I will do the preflight and look again before I pull the plane out of the hangar. I have done this many times. Sometimes, I go, sometimes I put the bird back in it's nest and close the doors.

I have also gone up for a look. If I am that confident, I probably will go unless I see things I don't like that are worse than forecast. Sometimes I have turned around and gone back.

The other part of this decision process is to keep the decision in abeyance at all times. Some conditions will stop you from leaving the house. Some conditions will stop you from completing the drive to the airport. Some will stop you from opening the hangar. Some will stop you from pulling the plane out. If you pulled the plane out of the hangar, you will probably take off. Actual conditions then will make the decision for you. Turn around and come back if you don't like what you see. Revise plans and go somewhere else if what lies between you and the original destination looks bad.

But don't simply stay home because there are some clouds in the area. Know the extent and level of the clouds, both at takeoff point, enroute and at the destination. Have plans for deviations. Know if there is better weather east or west, north or south of your straight line route and be prepared to go there.

But finally, and most important, always know that the weather is better ahead of you than it is behind. Don't take off in poor conditions unless you know that the weather is better enroute. Know that the weather at the destination and good and expected to remain good or at least expected to improve to good well before you get there.

Flying the plan

Flying in that stuff


First, remain clear of clouds. The rules are 1000' laterally and 500' vertically. If you are under the overcast and dodging showers, this is problematic. Flying through the virga is almost like flying through a cloud and in fact, it may look like a cloud. You cannot tell in this case what the actual cloud bottom is, so where is 500' below it? Dodging through the cumulus puffies to get on top may also violate the 1000' rule.
 
The legal/safe equation works both ways. What is legal may not be safe and what is safe may not be legal. A 0/0 takeoff in IFR may be absolutely legal, but I cannot think of any circumstances that it would be safe for single engine, single pilot GA. Being within 1000' of the clouds may not be legal, but climbing up through a gap that is 1500' wide and 3 miles long to get on top while using flight following would seem to be as safe as any other endeavor. Dragging a wing in the cloud to turn back and continue climbing in that gap would seem equally as safe.

Did I mention Flight Following? If the weather isn't more than decent, you should always use it. Any level of cloud cover reduces your ability to see other traffic. While Flight Following cannot relieve you of your responsibility to see and avoid, it reduces surprises to an acceptable level. Using flight following also presupposes that you will be flying well above treetop height which also cuts way down on the potential conflict of powered hanggliders and ultralights.

But it ultimately comes down to flying under it or flying over it.

Flying under it

This is the least palatable option to me unless it gives me at least 1500' AGL. I am more comfortable with more than 2000'. The reasons for this are many. Lower altitudes make flight following less available, which means that no one is watching out for you. Sandwiched between clouds and ground, the visibility is poor to downright bad. It is harder to find landmarks and towers as well as other traffic, and virga degrades visibility ahead.

But even here, there are some strategies that make it as small a risk as possible. Stay as high as you can. If this means deviating towards the lighter areas, do so. Do not hesitate to turn towards that lighter area. It is better to make a 30 degree turn towards the light area now than a 90 later. It also gives you more time to see what lies in that lighter area before you get to it. There may be another low cloud right behind the opening that you won't see if your approach is across the face of the nearer clouds.

Use what ground visibility is available. This means the ground visibility ahead of you, not to the side. If the clouds are broken, you may be able to see sun spots on the ground which will define the shape of the clouds ahead.

Do not give up altitude to duck under a cloud in front of you unless you can see the ground well ahead under the edge of that cloud. If you do duck under it, be spring loaded to do an immediate 180 if the situation under it is not as expected. This means having already decided where the light area is and be ready to turn in that direction.

I find this to be the most exhausting flying I have done. Under the clouds is bumpy, and generally hot. You cannot spend much time on instrument scans or chart reading. The view ahead requires constant attention. You must be constantly scanning the ground and the clouds ahead for breaks and pathways around the lower clouds. If it is at all possible, get above it.

Flying over it

Flying VFR on top gets an undeserved bad rap. The only caveat I can see is that you shouldn't get out of sight of holes that you can get down through. In other words, don't strike out over a solid deck unless you are more than sure of how wide it is. I have been on top of a solid deck several times and it is a little unnerving. The first time I was flying south along the western edge of a front. It was a solid deck to the east, but the ragged western edge began literally under my path. Sometimes the edge would be 5 miles west of me and sometimes I could see the ground momentarily out the left side. On other occasions, I knew from personal observation how thick it was and how much ceiling was under it as well as where it ended. On another occasion, even though there was no room under it, I could see the far edge of it some 10-15 miles away and I was 3500' plus above the top of the deck.
You can recognize holes without actually being able to see down through them. On top of broken clouds, holes will appear as large darker areas at a low viewing angle. Over solid overcast, the appearance of lifted areas also signals the potential for holes. A lifted line will mark the end of the solid stuff.

That covers flying "on top". There is a much broader area covered by flying above the bases of broken clouds. Imagine the scenario of broken clouds with bases at 2500'. You are eastbound and want to fly at 5500' The mass of the clouds is only 2000' thick, but the lifted areas extend up to 7000'. This is a common southern summer afternoon. And it is some of the most beautiful flying you can do. Get to your desired altitude and go slaloming among them.

Large billowy areas extending above your altitude are normally benign. You normally can fly close to them while picking your way towards your destination. The centers of them may be bumpy (that is what is causing the lifting), but normally the air around the edges is only slightly bumpy. It will be less bumpy on the sunny side than the shady side, if that makes any difference in your choice of which way to go around the area.

Do not get too close to a lone column of cloud extending upward. This may well be an incipient thunderhead. The air all around it will be rough. If the top is beginning to mushroom, get out of that area.

Flying in it.

I know it is not legal to actually fly in a cloud, VFR. But if you do fly in less than perfect conditions, sooner or later, you will find yourself with no horizon and no ground contact. It has happened to me and the VFR into IMC statistics say that it has happened to many others. If we assume that for every bad outcome, there have been many episodes that have been survived, then the incidence of this is fairly high. This is not intended to be a condoning of deliberate flying into IMC, but rather a set of suggestions for how to survive when it happens.

Everything so far has been intended to provide strategies for avoiding this. Careful planning, leaving places in the schedule for changing flight days, changing routes to find clearer paths, flying in the same sky with clouds but staying out of them. But still, the time will come when you cannot avoid them. Be prepared for it. Sooner or later you are going to find yourself either in them or with no choices but to go into them. Always be ready for this circumstance. If you have followed all the advice so far, you have chosen to put yourself in a position where it is likely to happen. You have done all that you can to minimize that possibility, but the only way to reduce it to zero is to stay on the ground except in CAVU conditions.

Consider my experience flying out of Carlsbad in 2003. I tried to go under them but found very quickly that didn't leave me enough ground altitude to clear a tall silo. I know there is clear air 5 miles behind me, but making a 180 will take me over ground I didn't see when I went in. I also knew that the layer was only a few hundred feet thick. What are the options? Clear air five miles behind me, 700' AGL and lowering ahead, no time to check the sectional for towers, etc and decide on a left or right 180. Only a couple hundred of soup above me. Best choice is to go up. Throttle up, pitch up, get on the AI and DG. As soon as climb is established begin the turn back to clear air. Maintain the desired heading and stay on the AI until you break out. Don't look for the openings, just stay on heading. Now, this course of action only works when you know that the tops are nearly flat and the soup is only a few hundred feet thick. I knew this because I had approached the cloud shield above the tops and saw that they were flat with no apparent openings before deciding to try under them.

Was it legal for me to deliberately climb into a solid layer? Absolutely not. Was it the most logical choice? I think so. This then comes back to the choices you must be willing to make if you fly VFR in less than perfect weather.

Now, think about trying to climb on top through an opening that isn't quite large enough. First, you have to know you can get on top. Weather briefings can seldom give you this number and the tops are seldom level. The place you are may have tops several hundred feet higher or lower than any number you have. If you are at 1500' and the top is at 5000', you can't find a hole large enough to do it. 3500' at 500fpm is 7 minutes. Seven minutes at 90mph is 10.5 miles. Unless the opening is 10+ miles long, or wide enough for a circling climb, you won't make it. But this case is at the bad end of the spectrum. Generally, you shouldn't have to make more than 2000'.


Experience says that openings are long and narrow. Generally too narrow to complete a 180. The good news is that the closed ends form "valleys". One end slopes away to the top, the other end generally slopes away to the bottom. Quite often, starting from the end which slopes down and climbing towards the end that slopes up, you can make it. But be sure to watch your airspeed. It is easy to fall victim to the idea that you can nose up a little more and make it.

If the valley is not quite long enough, you are faced with 2 choices: 180 and continue the climb or continue straight ahead into the cloud for the remainder of the climb. Both choices will put you into the clouds for some period of time. The valley is seldom wide enough for a 180 and the other choice means going into the cloud for the balance of the climb.


The idea of climbing straight ahead is more appealing than doing a 180 in the cloud, but there are some pitfalls to this choice. First, as already mentioned is the tendency to increase the pitch angle to climb faster and letting the airspeed get too low. Next is that you don't know how long you will be in the cloud. The slope of the valley past the hump you are going into may match your rate of climb all the way to the top.


The choice must be made based on how far you are from the tops. You have to base your decision on what you can see long before you run out of valley. Watch the cloud and the altimeter as you approach the end of the valley and if you need more than a few hundred feet, make the 180. Get over to one side (I go to the right) to the point of dragging that wing along the wall and start the turn before you run into the clouds. Maintain a constant rate turn with TC and AI until you are back in the valley. If the valley is not wide enough here, you will go into the cloud at some point in the turn. This will require more than 180 degrees and you must reverse your turn as soon as you pop out.

Once you are in the cloud, do not swivel your head around, looking for the light areas. This is a sure invitation for vertigo. Get on the instruments (AI, DG and airspeed) before entry and stay there. Don't change your mind. If the intent was to fly straight ahead, continue straight ahead. If the intent was a 180, continue the turn.