How Low Can You Go?

Running scud or operating from small fields puts low altitude skills to the test


With all too chilling regularity, pilots who fly close to the ground wind up on the losing side of the battle against wires, towers and other obstructions.

There are many reasons pilots fly too close to obstructions, and some of them are legitimate. Forced landings are what they are. Approaches to and takeoffs from small airports carry risks that may be unavoidable. Buzzing, enjoying the scenery down low and pressing on into lowering ceilings, however, open the aircraft to extraordinary risk from stationary objects.

Agricultural pilots, by the very nature of their jobs, operate in an airspace filled with obstacles of every description. Avoiding electric transmission cables, towers of various heights, power and phone lines and poles, and other hazards to extreme low level flight is a daily factor in their lives.

By contrast, most general aviation pilots only venture within the grasp of these objects on takeoff and landing. If tempted or forced into extreme low-level flight, they usually lack the knowledge critical to increase their odds of avoiding obstacles.

In 22 years as an ag pilot, I have dealt with all of the hazards of low-level maneuvering. The daily routine of flying close to ground objects, as well as those thankfully few times when I was unable to avoid them, have taught some hard lessons that should make most pilots think twice before flying at a low altitude that may be far beyond their level of experience.

Extreme low altitude flights could put your certificate in danger, assuming you survive the experience. Many of the techniques that make low-altitude flight survivable are in direct violation of FAR Part 91. However, knowing them may help you land safely should you ever find yourself in this proverbial hard spot. The main concern at that point isnt the legality of the issue but for you to avoid any obstacles present and climb to a safe altitude in the shortest possible time.

FAR 91.119 states that if youre flying below 500 feet above the surface in a non-congested area, your aircraft cannot be flown closer than 500 feet to any person, vessel, vehicle or structure. Depending on the terrain, you may not consider 500 feet above the surface to be particularly low. Even so, its an altitude below which youre likely to find many more obstacles than you would at a higher level.

Thats not to say that higher altitudes are free of danger. Many objects, such as radio or television transmitter towers, can rise above typical pattern altitudes.

For example, if you ever happen to be flying in the lower Sacramento Valley of California, keep in mind a cluster of three towers about 13 miles south of Sacramento. Each one reaches to 2,000 feet above the ground. They are depicted along the very top of the southern side of the San Francisco Sectional, but are quite easy to overlook if you arent familiar with the area. Their presence makes 2,000 feet a hazardous altitude in this vicinity, and if for some reason youre flying there and cant climb higher, you must at all times know your exact position relative to them.

High towers are usually painted in contrasting colors of orange-red and white and marked with clearance lights. Sometimes they have strobe lights as well. However, under certain weather and sun conditions even flashing strobe lights may not make them highly visible. You can find yourself quite close to a tower before seeing it.

Remember that most tall transmitters are braced by guy wires that can extend out hundreds of feet from the tower base. A number of aircraft have spotted and successfully avoided a tower only to strike a guy wire, which can be nearly invisible. When you see one of these tall structures, and are flying at or below its height, you need to give it a very wide clearance, and the lower you are, the greater distance you must detour around it.

When youre flying in mountainous terrain, or through a canyon or river valley, you must remain constantly aware that power lines and other obstructions may be strung across your flight path. These are not highly visible objects under most conditions.

This means that when youre cruising down a canyon or valley below the surrounding high ground, any lines or cables crossing it will be extremely hard to spot, rendered nearly invisible by the backdrop of surrounding mountains and/or trees. Many aircraft have struck these objects without the pilot realizing an obstacle was present until the impact. Although some cables have balls, strobe lights or reflectors on them, that still doesnt guarantee that youll see them in time to avoid them.

Even flying just above the high ground on either side isnt always enough. Some wires across river valleys are elevated on towers and cross high above the surface. This extra height is to allow ships masts and other objects passing below. You can be several hundred feet above the water surface and still be in danger of striking one or more of them.

Scud Runners Beware
A certain recipe for disaster awaits pilots who continue flight into deteriorating weather while attempting to maintain VFR. The unlucky ones find themselves forced lower and lower, trading altitude for visibility. Like a game of chicken, they either blink, and land, or press on. Sometimes they make it; sometimes they dont.

If forced into pressing on into a lowering cloud deck, you may be driven down to the height of cross-country electrical transmission lines. Some transmission line towers are taller than 200 feet, but in most cases they arent tall enough to be required to have high-visibility paint or to display hazard lighting. Some, but not all, are depicted on sectional charts. That means you may not have much time to decide how to cross it.

If you find yourself at any altitude where you think obstructions may be present, and for some reason are unable or unwilling to climb higher, decrease airspeed immediately. The faster your cruising speed, the less time youll have to avoid obstacles that suddenly appear over your aircraft nose.

Speed reduction should be enough to slow the rate of closure of potential obstacles while still allowing you to direct all your attention out in front. Thus, you should avoid slowing to such a low airspeed that you have to focus on keeping your machine from stalling.

Theres another good reason for decreasing airspeed at low altitude. Rapid control movements may be necessary to avoid an object that suddenly materializes out of nowhere, and slowing to below maneuvering speed will allow full deflection of control surfaces without risking airframe damage. When your airspeed drops below Vfe, you can lower the flaps to improve the stall margin.

While youll need to be on constant lookout for approaching obstacles, dont make the mistake of staring straight ahead with a fixed gaze. Keep your eyes moving, and scan out beyond your airplane at least 45 degrees on either side of the nose as the ground rolls by beneath you.

Be especially alert for any object that is at or above your eye level, and be prepared to take action to avoid it as soon as it comes into view. In the case of cross-country power transmission lines, youll most likely see one or more of the towers, which are usually about a quarter-mile apart, before you spot the cables themselves.

Keep in mind that a ground wire runs along the top of many cross-country transmission lines. You must stay above the towers to avoid striking it, so if youre about to cross the lines at minimum altitude, dont be tempted to do it at the low point of cable sag, below the level of the towers. The ground wire is of much smaller diameter than the main cables, making it very hard to see, even in good weather.

If experience or the sectional tells you that a transmission line will be appearing somewhere up ahead of you, alter your heading so that youll be approaching the tower line at an angle. That way, it will come into view gradually off the side. Youll have a little extra time to decide how and where to cross it, and your evasive action will not be as extreme if it catches you by surprise.

Over or Under
In extreme cases, as when a low ceiling obscures the tops of the towers or when takeoff performance is inexplicably poor, it may be safer to cross under the cables rather than attempting to climb over them.

I once watched in horror as a Bellanca Cruisair carrying a pilot and three passengers came within only a knot or two of stalling and plunging into a set of transmission lines. The airplane had taken off downwind, and the pilot elected to try to climb over the 100-foot-plus lines rather than maintaining a safe airspeed and flying below them. There was plenty of room to go under, especially near the towers, where the cables are higher off the ground.

Although the pilots first mistake was in not paying attention to wind direction, his second – and far more serious – error was in making a mushing, faltering low-speed climb to get over the cables. The Bellanca cleared the ground wire along the top by only a few feet. He and his passengers remained alive solely by sheer luck, yet he was quite indignant when later told by a CFI who had witnessed the incident that he should have elected to go under the lines.

If you feel its safer to fly under a set of transmission lines, try to do it closer to a tower, where the cables are higher above the ground, rather than directly between two towers, where the cables sag to their lowest level. This sag is more pronounced in hot weather, when the cables expand. Be alert for objects such as fences and road signs in your flight path, and keep your wings level while crossing below the lines.

And if Youre Nuts
During extremely restricted visibility, theres a possibility that you might be forced even lower – perhaps to a height where you may need to avoid power or phone lines that are strung from pole to pole. If this is the case, you wont need anyone to tell you that youve gotten yourself into deep, deep trouble. Surprisingly though, there are a few pilots around who have been in this dire predicament and have lived to tell the tale.

Although the obvious solution is to make a precautionary landing, there have been recorded accidents in which pilots pressed on before hitting utility lines that were less than 30 feet off the ground.

Power and phone wires can be very hard to see, and this holds particularly true for a nervous pilot in poor weather who has never had to look for them before. This means that youll most likely have to determine wire location and orientation by placement of the poles, which show up fairly well against the sky, and the angle of the cross-arms that support the lines.

The cross-arms atop the poles can give you an indication of the height and direction of the wires, which usually run at a ninety-degree angle to the cross-arms. There are infrequent exceptions though, so try to positively identify wire orientation rather than assume it from cross-arm position alone.

When you detect a set of wires, dont wait until the last minute and then make an abrupt pull-up followed by a hard pushover to get back down on the other side. This can be dangerous, especially under low airspeed/low visibility conditions. A steep pull-up may put you into the overcast with your airspeed at or just above stalling. In addition, the gs from the maneuver can induce disorientation that can lead to a loss of control.

Its best to begin a gentle ascent as early as possible, initiate a smooth, shallow-angle climb to barely clear the lines and poles, then ease back down again once youve passed over them. Even if you climb into the clouds, the duration should be short enough that you can recover on the other side before things get too far out of hand.

There may come a time when, like the Bellanca pilot above, the time is right to fly under one or more sets of power lines. Although you have placed yourself in an extremely hazardous situation, going under the lines may be the only way of coming out unscathed. If the visibility is truly awful and you lack confidence in your instrument flying capability, this could be your last, desperate alternative, rather than pulling up sharply into a low overcast to clear a set of rapidly approaching wires. If you have insufficient instrument skills to maintain your aircraft in a stable climb during zero-zero conditions, the term stall-spin from an unusual attitude comes to mind as a possible result of trying to pop over the top.

The thing to remember is that as long as youre airborne and in control of your machine, you still have some options. And until they run out, you have at least some hope of survival.

If you think that going under the lines is the only solution, observe the approaching wires. If theyre high enough to get under, youll see the space below them widening as you get closer. If theyre too low, the space will remain the same or get narrower. Remember that the aircraft vertical stabilizer extends above your cockpit view, so youll need to allow for it, and make certain to get down low enough for it to clear the lines.

Youll have to make a decision quickly, and your stress will certainly be increased by the possibility that the pole line youre approaching may have one or more smaller, less visible phone or power wires strung beneath it. If so, they may run at about the height youll be at when passing under the main set. Also, check for obstructions such as fences, road signs, irrigation vent pipes, and other obstacles in your flight path.

Once youve committed to going under a set of wires, dont attempt to change direction by banking normally. The low wing may contact the ground, or the high wing may strike the lines. Instead, if you have to avoid an obstacle under the wires at the last second, try to keep the wings as level as possible by skidding the aircraft around it with the controls crossed. Remember to skid in a direction away from the nearest pole.

Down to the Wire
Anytime youre flying below the tops of the power poles, theres always a chance of striking one or more wires. The most important action to take in a wire-strike, or in the few short seconds before an inevitable strike occurs, is to instantly add maximum power with throttle and rpm while you still have flying speed and control of the aircraft.

The increased engine rpm and aircraft energy will help break the wires, giving you a better chance of making it through them with flying speed intact. In addition, theres the possibility that a length of broken wire may have become attached to your machine. Its always wise to assume that this is the case, unless youre 100 percent certain that its not.

Since youre slowed down anyway, the added drag could be enough to stall the airplane, and max power could make the difference between staying airborne and making an uncontrolled descent. Keep the throttle and prop control firewalled until youre well past the lines.

If no other lines are ahead, and youre somehow able to climb, gain altitude as soon as practical. Increased altitude lessens the chance of a wire that may be attached to your aircraft passing over other lines, wrapping around them, and either adding to the burden youre already carrying or pulling you down. Depending on the length of the wire, you may have to make climbing turns to stay within a line-free area until you reach sufficient altitude. Make the turns as shallow as possible, keeping in mind the added drag of the trailing wire.

Once youve reached a safe height, stabilize your aircraft in level flight and inspect all visible structure and control surfaces. Thoroughly check its low-speed flying characteristics with a view toward landing soon.

If your airplane responds satisfactorily to control input, dont be in such a hurry to land that you make a poor decision about where to put it down. Choose a touchdown site carefully. If you may be carrying a length of wire, pick a landing site with a long, unobstructed threshold and make a straight-in approach at as steep an angle as youre comfortable with. This will lower the possibility of the wire contacting objects on the ground before youre ready to touch down.

If length permits, land well down the runway. Depending on how much extra drag is present and the length of the landing site, youll probably want to come in somewhat hotter than usual. At a controlled airport, have someone in the tower look over your airplane before you land to determine whether youre carrying a wire.

Once youre on the ground, resist the temptation to go around if the landing isnt quite normal. If youre carrying a length of wire, its better to settle for a ground-loop, or even run off the end of the runway at a relatively low speed, than to risk a stall-spin brought about by a high-drag, low speed climb-out from an aborted landing attempt.

Keep in mind these and other emergency low level and slow flight procedures specific to your aircraft, and periodically rehearse mentally what actions to take if you should ever be caught looking up at an obstruction. Dont even think about practicing some of this stuff, such as flying close to towers or going under lines before a real emergency occurs to get the feel of it. Besides being illegal, these are dangerous maneuvers unless you have specialized training and experience, and they should be used only as a last resort in an actual emergency when all other alternatives have run out.

The main thing is to have definite procedures in mind to carry out, and to give some thought as to how youll accomplish them in a critical situation. If you do this, youll have a much better chance of making the right moves during those few perilous seconds when your life may depend on it.

Also With This Article
Click here to view “Living the Low Life.”

-by J.J. Snyder

J.J. Snyder is a commercial pilot and A&P mechanic, and has over 13,000 hours, including 11,000 hours of agricultural flying.


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