Barry Schiff, aviation writer extraordinaire

My promise to provide an article from Barry Schiff’s series of books, The Proficient Pilot, is fulfilled this month with an article devoted to the challenging and dangerous practice of flying in marginal VFR weather.

Although I have published an article on this very topic and techniques to maximize safety in this marginalized flying environment, I chose this article as an example of Barry’s work because he provides a different slant and also his different slant essentially tells pilots why they shouldn’t carry on regardless.

I also selected this article because it didn’t include a selection of charts, diagrams or graphs for support and was easily transferred as a result and hope you enjoy Barry’s sage advice.

Should you wish to avail yourself of Mr. Schiff’s excellent offerings, visit the Aviation Supplies website at Barry’s URL:

http://www.asa2fly.com/Barry-Schiff-C137_category.aspx

To order books you can contact Aviation Supplies & Academics, Inc. at

7005 132nd Place SE Newcastle, WA 98059-3153 or tel. 800-272-2359 or 425-235-1500 or visit: www.asa2fly.com/.

Scud running is one of general aviation's most tempting and hazardous procedures. It claims numerous lives every year.

Lacking formal definition, this technique generally is regarded as an attempt to maintain visual flight in marginal conditions, such as when the ceiling (or scud) is less than 1,000 feet, and visibility is less than 3 miles.

Pilots criticized for scud running invariably defend themselves by pointing to regulations that effectively condone the procedure. They argue that VFR flight in Class G (uncontrolled) airspace during the day is allowed with a visibility of only one mile as long as the airplane is kept clear of clouds.

Though scud running may be legal, it can be extremely dangerous, and the danger increases as the performance capability of the aircraft increases. Also, consider that the weather conditions described above are less than the minimums required to complete many IFR (instrument) approaches.

Scud runners who get into difficulty usually do so by continuing into worsening conditions. Either disorientation or failure to see and avoid obstacles or terrain is typically the cause of a scud running accident.

Since it can be suicidal to continue visual flight into such adverse conditions, it is logical to wonder why these pilots behave so irrationally. There appear to be two reasons for their determination to plunge toward disaster.

The first, and most obvious, combines a pilot's overestimation of his ability with his determination to succeed and his optimistic attitude regarding weather conditions ahead. In other words, he is guilty of poor judgment.

The second reason is much less understood and often is a major contributing factor in scud running accidents.

When flying at low level in gradually worsening visibility, a pilot considering course reversal generally glances rearward first to appraise this escape option. Most pilots, after all, are not suicidal (despite occasional actions that seem to indicate otherwise).

But when looking behind him, a scud runner sees his fleeting ground reference points disappearing behind the veil of restricted visibility through which he had been flying. This creates an illusion that can lead him to believe that conditions behind are worsening or "closing up."

Contributing to this deception is the feeling that conditions ahead are improving because forward motion of the airplane causes progressively more of the terrain ahead to come into view. The overall effect of this illusion increases with airspeed.

Consequently, pilots are reluctant to turn around while the opportunity still exists. In most cases, weather immediately behind an airplane does not deteriorate that rapidly. If it was safe to overfly the area a minute ago, it usually is equally safe to turn around and do it again. The same cannot be said for the conditions ahead.

In addition to the obvious hazards, consider the complications of a mechanical difficulty. What normally would be regarded as little more than a nuisance or inconvenience can become a serious distraction with which scud running pilots are unable to cope. When obstacles are probing for the belly, pilots need to devote almost all of their attention to controlling the airplane and maintaining visual flight.

In the case of power failure while scud running, the emergency must be treated as an engine failure after takeoff. If the pilot is flying a single engine airplane, precious little time is available to select a landing site and prepare for touchdown.

Mechanical irregularities aside, scud running is uniquely hazardous because the pilot usually has had no training or preparation for this type of flying. Something as simple as navigation can be extremely difficult at 500 feet AGL with only a mile or so of visibility.

Those who doubt this should challenge themselves with an hour long, low level flight in VFR conditions. It is surprising how few checkpoints can be seen from 500 feet. Then imagine complicating the problem with limited visibility and a low, ragged ceiling.

Experienced scud runners usually abide by a set of self imposed rules. They seldom carry passengers because innocent bystanders should not be exposed to the risk. They rarely go themselves, unless an IFR option is available; this means that both the airplane and the pilot must be qualified and prepared to intentionally climb into the overcast as a means of emergency escape.

Scud running at night or in mountainous terrain is too risky to consider. Anyone attempting such a stunt has only himself to blame for the predictable consequences.

Scud running obviously is dangerous. However, if a pilot elects to underfly weather, he first should make a thorough study of the terrain and become familiar with the nature of en route checkpoints and obstacles. The most prominent of these should be highlighted on the chart.

When possible, a scud runner should plan to follow highways, railroads, and other forms of reliable guidance. Consider, however, that these also can lead to tunnels, bridges, and other hazards.

Pilots also should not expect VHF communications or navigational assistance at low altitude except when in the immediate vicinity of a ground transmitter (An ADF bearing might be the only available radio aid).

A course through the area should be plotted in advance. The chart should then be folded open to avoid having to fumble with it and becoming distracted at critically low altitudes. Some experienced scud runners recommend placing the chart between the thumb of the left hand and the control wheel so that it can be seen with minimal eye movement and vertigo inducing head twisting.

It also is helpful to mark the course line with five or 10 mile ticks to help keep track of en route position. When checkpoints are few and far between, the clock becomes an important ally; knowing how many miles are covered every two minutes, for example, provides a reasonably effective form of dead reckoning navigation.

Excessive speed complicates scud running. At an airspeed of 180 knots, for example, it takes only 20 seconds to fly 1 mile, which often is the limit of forward visibility. Little time is available to see and avoid obstacles, which seem to appear from nowhere.

At 60 knots, on the other hand, the pilot has a full minute, three times as much time, to appraise and react to approaching terrain.

Although reduced airspeed has advantages when scud running, a pilot must be careful not to go too far. Low level flying provides a greater than usual impression of speed. This causes some to believe they are flying too fast. As a result, they subconsciously reduce airspeed (especially when turning) to a dangerously slow rate.

Speed control, therefore, becomes a serious concern when scud running. It should be slow enough to avoid obstacles, but fast enough to provide stall protection while manoeuvring.

If a pilot inadvertently enters an area of reduced visibility (less than one mile), he should consider partially deflecting the flaps. This not only provides added stall protection, but also places the airplane in more of a nose down attitude, which improves over-the-nose visibility.

(Since helicopters have different capabilities than fixed wing aircraft, regulations allow pilots of these aircraft, during certain conditions, to fly VFR with no minimum visibility as long as they can see other traffic or obstacles in time to avert a collision).

Most scud runners give little thought to the threat of colliding with other aircraft. Flying in such limited airspace - limited by ceiling and visibility - a pilot feels very much alone. Some even report feelings of claustrophobia. But when following landmarks such as rivers, highways, and railroads through a patch of inclement weather, consider that it would be just as logical for a pilot heading in the opposite direction to use the same topographical guidance. And since a low ceiling compresses VFR traffic vertically, other airplanes are likely to be at approximately the same altitude.

Common sense suggests that scud runners fly to the right of highways, rivers or whatever landmark they have chosen to follow. This also places the course line to the left of the airplane, making it easier for a pilot to see at all times. Also, every available exterior light should be turned on.

Most novice scud runners have a tendency to lose altitude. This is because an inexperienced pilot perceives the natural horizon to be lower on the windshield than it really is, an illusion created when low clouds and restricted visibility obscure the true horizon.

On the other hand, some pilots are ground shy and tend to allow the aircraft to drift up toward the overcast. This partially explains why instrument flying skills are necessary even when flying in certain visual conditions.

Another illusion occurs when flying in a crosswind. At very low altitudes, drift is much more apparent, even distracting. This causes some pilots to perceive a slip or skid (especially in turns) even though the slip/skid ball is centered. Their actions to correct this sensation have led to numerous stall/spin accidents.

This is why some pilots, prior to scud running, tape one end of a six inch length of yarn in the center of the windshield. Glider pilots routinely use such a yaw string as a form of head up display to help detect and correct uncoordinated flight without having to refer to the gauges.

Another scud running technique is to fly along the downwind side when in a narrow valley that limits manoeuvring room. Should a 180 degree turn become necessary, this maximizes the space available. Turning into the wind makes the manoeuvre safer because this reduces turn radius; a turn away from the wind, of course, dangerously increases turn radius.

One problem associated with flying on the downwind side of a valley is that this places the airplane on the upwind (windward) side of the hills. A pilot unaware of this can be lifted into the cloud base by persistent updrafts.

Other scud running hints: keep a hand on the throttle at all times in anticipation of a sudden need to manoeuvre; when an immediate climb is necessary to avoid ground contact, do so at the best angle of climb airspeed (Vx); when practical, use climbing S turns to maintain a forward view; it usually is best to maintain an altitude two thirds of the way between the ground and the cloud base; exercise extreme caution when flying over snow covered terrain that blends with a milky overcast to eliminate any visual horizon (a condition known as whiteout); similar caution is required when flying toward the sun in dense haze; and never fly beyond the point of no return.

When it appears that a pilot is sticking his neck out too far, he should exercise one of two options: swallow his pride and turn around (usually the simplest), or try to contact air-traffic control and obtain an IFR clearance to climb into the overcast, leaving the hazards of scud running behind and below.

If neither of these options is possible or practical, consider a precautionary landing. Occasionally, it is better to risk this inconvenience and potential hazard than to continue into deteriorating weather with only a hope and a prayer that there is light at the end of the tunnel.

Pilots who collide with the ground while scud running usually do so because of some inexplicable compulsion to continue when conditions clearly dictate otherwise. Even fully qualified instrument pilots fly into frightful conditions while struggling to maintain visual contact with the ground. They are reluctant to give up until it is too late.

Although it is illegal to intentionally climb into IFR conditions without a clearance, such an option might be considerably safer than continuing in IFR conditions at low attitude.

If the situation is desperate, a spiralling climb to avoid surrounding, higher terrain eventually places the airplane safely above all obstructions. Also, the availability of navigation and communications facilities increases with altitude.

While ascending into controlled airspace (literally as pop up, IFR traffic), the transponder should be squawking the emergency code (7700) to alert air traffic control of your presence. Once communications are established - on the emergency frequency, if necessary - and a clearance is obtained, the remainder of the flight becomes routine. Once you land, however, you can expect to be called on to explain your violation.

If the pilot or the airplane is not IFR qualified or if icing conditions are forecast, a pilot probably should not yield to the temptation to scud run.

A cardinal sin is to pass up an en route airport or reasonably attractive landing area when the situation becomes critical. At such a time, a pilot should take advantage of any opportunity to shift the odds in his favour.

If deteriorating weather encourages a pilot to land, he might have to fly the traffic pattern at an abnormally low altitude, which is not without hazard. In the downwind leg a pilot is accustomed to viewing the runway from a 30 degree angle above and abeam. If a scud running pilot sights the runway along the same line while at a significantly lower altitude, the airplane is naturally positioned much closer to the runway.

Consequently, the pilot has less room to execute turns from the downwind leg to base, and from base to final. He invariably compensates by using abnormally steep turns (at relatively low altitudes).

A pilot aware of this problem would intentionally fly farther from the runway than appears normal. In other words, the pilot perceives being low for the simple reason that he is.

Another problem is that a pilot flying a low pattern altitude tends to begin descent prematurely (when downwind and abeam the approach end of the runway, for example). But since he is low to begin with, such a descent keeps the airplane well below the normal, visual glideslope. Descent should be delayed from a low pattern altitude until intercepting a normal slot.

When turning at very low altitudes, pilots have a greater than normal sensation of speed because of their close proximity to the ground. Often, they counter this by subconsciously reducing airspeed, an action that cannot be tolerated at a time when the airplane already may be turning sharply at low altitude (for reasons discussed previously).

Airspeed management while scud running must be based solely on the instruments; seat of the pants corrections can be lethal.

Although this discussion deals with the techniques of scud running, it must not be interpreted as any form of encouragement. The best way to deal with the problem is to avoid it in the first place.