Going PVFR

Some years ago, I was detailed to Kotzebue, Alaska, in late February to assist in conducting a moose survey in the Selawik River drainage area. Kotzebue lies well north of the Arctic Circle, and in February, the sun angle is very low. Kotzebue also lies north of the tree line, so there are no trees and few shrubs. In fact, this country offers little in the way of topographic relief of any kind. In February, everything is covered with a blanket of snow. Combine a low sun angle with a lack of contrasting features, and you have the classic Alaskan phenomenon known as whiteout, meaning simply that it is very difficult to see anything, and often impossible to maintain a visual horizon or navigate without electronic aids. Whiteout conditions can be a killer, whether you are in an airplane, on foot, or on a snowmobile (see " Moose Tracks," August 2002 Pilot).

The day I arrived in Kotzebue, the weather was gloriously clear, visibility at least 100 miles, and no wind. The Piper Super Cub I flew from Fairbanks cruised along at a leisurely pace over the vastness that is northern Alaska, and my six-hour flight ended in a satisfying, smooth ski arrival on the lagoon ice near downtown Kotzebue.

PVFR Box

The AOPA Air Safety Foundation offers two Seminars-in-a-Box that could help local pilot groups: "Weather Strategies" and "Weather Tactics." Also, the current Nall Report discusses how lethal continued VFR into IMC can be. The Nall Report is free on the ASF Web site ( www.aopa.org/asf/). The Seminars-in-a-Box can be ordered for just the cost of shipping and handling ($24.95) and include the full program, 50 Safety Advisors, and door prizes.

By the next morning, however, conditions had changed. A visit to Kotzebue Flight Service revealed local weather with a reported ceiling of 5,000 feet, and visibility five miles in very light snow. The village of Selawik, near the other end of our survey area, had almost identical weather. By definition, and by regulatory decree, this was legal basic VFR weather.

It was my good fortune that day to be briefed by a flight service specialist named Warren Thompson — a fellow who had worked at the Kotzebue Flight Service Station forever, some folks claimed. Thompson is also a very experienced northwest Alaska aviator, having flown for several air taxi operations over the years. I was scheduled to work with George Walters, an experienced commercial pilot from the Bethel area. Bethel, 370 miles to the south, presents many of the same challenges to aviators as are found in Kotzebue.

Thompson gave us a textbook FAA standard pilot weather briefing, and then offered a few insights of his own. He pointed out that for air taxi pilots, the current conditions might be acceptable, since they could simply climb up to 4,000 feet, well above any terrain in the vicinity, and auger along on instruments. Even though they would be legally operating in "VFR conditions," and under visual flight rules, these folks would be operating solely by reference to their instruments, since there was nothing to see within the range of the prevailing visibility. No trees, no mountains — nothing to offer any contrast, and no horizon. Some northern pilots offer an apt description of this condition: "flying inside a milk bottle."

Thompson noted that to attempt to fly low-level moose surveys on a day like this would be considered by most pilots in northwest Alaska to be suicidal. Our aircraft were not fully instrument-equipped, and we would be flying within 500 feet of the surface at all times, an impossible task in the conditions at hand. Not satisfied with simply telling us we shouldn't fly moose surveys that day, he proposed an experiment: He suggested that we conduct a takeoff from the lagoon, pass the town, and, while keeping Kotzebue close behind, get a good look at the inside of the milk bottle — directly toward Selawik. That way, all we would have to do was turn back toward town for a visual reference if we didn't like what we saw. Apparently, he hoped that even I could successfully conduct a 180-degree standard-rate turn in the goo.

It turned out that this simple experiment was both elegant and instructive for a pilot used to flying on Kodiak Island and in Alaska's vast interior, most of which is covered with trees and terrain features. It also caused me to start thinking about other similar conditions, and a way to describe this phenomenon. There appears to be no official acronym, at least not in the Federal Aviation Regulations or the Aeronautical Information Manual.

In those volumes, I found a definition for visual flight rules, or VFR — a set of operating rules that requires reported ceilings to be 1,000 feet or more with visibilities of three miles or more. Additionally, FAR Part 91 specifies cloud clearance requirements for operation under visual flight rules. I also found instrument flight rules, or IFR — a set of rules that govern flight operations when ceilings are below 1,000 feet and/or visibilities are below three miles and when cloud clearances can't be maintained at your current location. Nothing ambiguous there, you might argue.

But then I noted the definitions for these same acronyms when they are given in a weather forecast. For example, what does it mean when a terminal forecast predicts the weather at my destination to be VFR at the time of my proposed arrival? In this context I found a description of VFR weather as prevailing when ceilings are greater than 3,000 feet and visibilities are greater than five miles, significantly better weather than that required to operate under basic VFR in the regulations. In the forecast context, IFR weather is defined as ceilings of 500 to 1,000 feet and/or visibilities of one to three miles. Searching further I found low IFR, described as the condition when ceilings are less than 500 feet and/or visibilities are less than one mile. Finally, I found defined marginal VFR, or MVFR — when ceilings are 1,000 up to and including 3,000 feet and/or visibilities are between three and five miles.

Confused yet? Remember, one set of definitions represents the conditions that must prevail for us to legally operate under a specific set of operating rules. The other set of definitions is used purely for interpreting or "visualizing" forecasts. In real life, though, what we really care about when we are operating under visual conditions is whether we can see well enough to maintain a wings-level attitude, navigate by what we see out the windshield, and avoid others who are doing the same. If you think about it, neither of the above noted definitions of VFR gives the pilot assurance that he or she can see well enough to fly in the prevailing conditions. They offer some indication, but no guarantees. Part of the problem is the way we learn about weather and its effects on flying during our training.

Think about it — when someone says VFR weather, what comes to mind? I would wager that most folks do not visualize three miles of visibility and a solid overcast at 1,100 feet. Are we properly equipping our pilots-in-training with the vocabulary and the understanding of what is required to safely operate an aircraft visually? Pilots often hear the magic term VFR conditions, and they're ready to go flying. By the same token, many pilots blithely accept the oft-heard flight service statement, "VFR flight not recommended," as a commandment. Unfortunately, most pilots are never exposed to actual marginal weather during their flight training. Three- or four-mile visibility can be pretty disorienting, and the perspective from 500 or 600 feet agl presents a very different view, and a different set of challenges, than flight at 3,000 feet agl.

Most of all, I believe we fail to teach primary pilots that what is really important is not so much whether the conditions meet some specific set of standards, but rather whether the pilot is actually able to see anything while in flight. This is, after all, the essence of visual flight. After my experience in Kotzebue, I began to refer to this sort of weather condition as PVFR, which stands for pretend visual flight rules. I define PVFR as: A situation where the meteorological conditions meet the definition of VFR, but conditions are such that there are too few visual references within the range of the prevailing visibility to keep the airplane upright by reference to a visual horizon and to safely navigate. In other words, the pilot is actually in instrument meteorological conditions (IMC). To simplify the definition a bit: PVFR prevails when one is in VFR weather conditions, but can't see anything except the weather.

It is not just the multiple definitions that can be a problem for the aviator. First, you must determine what the conditions are, and are most likely to be, throughout the flight. Then you must determine whether those conditions are adequate to safely operate over the proposed route of flight. Basic VFR conditions in the prairie states may result in IMC in the mountains. When the flight takes us over water or trackless terrain, three miles of visibility may not be adequate for safe operation.

Some pilots suggest that this notion of pretend VFR is principally an Alaskan winter phenomenon, but examples abound in all seasons and in the lower 48 as well. Not convinced? Try flying in the mountainous western states during a summer when forest fires are raging.

Flying a Cessna 185 north from Fairbanks one summer day in two to three miles of visibility in smoke, I received a report from a helicopter pilot who said that conditions deteriorated significantly farther north. I executed a 180-degree turn, and as I faced into the sun, my forward visibility went to virtually nothing. A simple difference in sun angle was enough to completely change the effective visibility. Unfortunately, this occurred in mountainous terrain, and at low altitude. When visibilities lower, most pilots naturally fly closer to the surface, ostensibly to maintain better ground contact. A heart-stopping climb to a safe altitude, followed by a pop-up instrument clearance back to Fairbanks, completed my flying day, safely, but with more food for thought.

Consider the conditions encountered when flying on the East Coast in the hazy heat of summer, when visibilities are rarely more than a few miles. I suspect that in those conditions, most pilots are relying much more heavily on their instruments than they may realize or admit. That new GPS unit is pretty handy here, eh? Even though conditions may be above basic VFR criteria, a vacuum failure or electrical failure could easily precipitate a very real emergency, or, at the very least, some uncomfortable moments.

Now imagine being seven miles offshore over the ocean, at night, with prevailing visibilities in haze of around five miles. I contend that PVFR may have been an important factor in the John F. Kennedy Jr. accident. If you are seven miles offshore and the visibility isn't seven miles or more, there is simply nothing outside the aircraft by which you can maintain visual orientation. As in the previous examples, while this condition may meet the legal requirements for VFR flight, these are, in fact, instrument meteorological conditions. If the pilot is not instrument-proficient, and perhaps just as important, if the pilot fails to recognize that he or she is actually in IMC, the flight is very likely to end in tragedy. Remember, these meteorological conditions would be accurately described as VFR, and would be briefed as such in a preflight weather briefing.

So, what can the prudent pilot do to ensure that he or she doesn't fall into the PVFR trap? First, we all need to give a little more thought and study to the definitions used in weather forecasts. Not just the examples listed above but, for example, in a forecast, what does the term occasional mean, as opposed to frequent or intermittent? How about widespread versus isolated? A functional understanding of the definitions of weather and forecast terminology is essential to successfully interpreting the available weather products. An appropriate interpretation of the weather briefing and an understanding of what the weather descriptors mean are vital to safe VFR flight.

Second, the next time you are driving your automobile in smog or heavy snow, look critically at what you see out the window, and imagine what that view would mean in an aircraft operating under VFR, perhaps at night. The idea is to learn to picture what forecasted weather actually looks like in real terrain. On days when you opt not to fly because of forecast inclement weather, pay attention to the actual weather conditions that evolve as the day progresses. This will not only help you to visualize weather conditions based on a forecast, but also help you to improve your forecast evaluation skills.

Third, find a competent instrument instructor who is willing to do some VFR flying on a marginal day. Use good judgment in your choice of places to fly and the weather you fly in. Study the country carefully on a clear day in advance, so that you have a good hazard map of obstacles and their heights prior to flying on a poorer-weather day. Above all, in your experimentation, be sure that you have the option of safely transitioning to IFR if need be. This experiment, like mine in Kotzebue, will help you understand that a weather report of basic VFR conditions may or may not imply that it is actually safe to fly in those conditions visually.

The idea is not to train you to fly visually in marginal conditions, but rather to show you how ugly PVFR can be, and how dangerous that operating condition really is. The idea is to encourage you to avoid it.

Above all, every pilot needs to understand the conditions he or she is operating in. You are either in safe, functional visual conditions or you are in instrument conditions. Unfortunately, there is no clear and well-defined line between the two, so learn to evaluate the effect the prevailing conditions may have on your flight. If you find yourself creeping into PVFR, it's time to perform a strategic retreat, and the earlier, the better.

Finally, learn to fly in instrument meteorological conditions, and stay as current on instruments as your budget and schedule permit. Remember, though, every year a number of instrument-rated pilots succumb to PVFR and fly their aircraft into a mountain or other object, albeit right side up. The problem these pilots encountered was often PVFR of the most insidious sort — VFR conditions that degrade until there is simply nothing to see out the windshield. Unfortunately, the transition is often subtle, the pilot is reluctant to "pop-up" IFR, and after a while, the pilot may not know precisely where he or she is. Denial allows the pilot to get in deeper and deeper. The pilot has now entered into the world of PVFR flight, and there are few conditions more dangerous in general aviation.

George Walters and I sat on the ground in Kotzebue for a week that February, in PVFR weather the whole time, and never turned a prop in pursuit of our moose surveys.

I'm guessing that the moose never even noticed.

Michael T. Vivion, AOPA 604565, of Fairbanks, Alaska, is a wildlife biologist. He has accumulated 9,500 hours in 31 years of flying and owns a Cessna 170B.