THE HAZARDS OF LOW ALTITUDE AND OFF-AIRPORT FLIGHT OPERATIONS
As pilots start to prepare for another season of flying, there are some annual safety issues that need to be reviewed.
by H. Dean Chamberlain
First is the suggestion that pilots who haven't flown much over the winter should get some recurrent training with their local flight instructor. With a little planning and the flight and ground training needed to qualify for a phase of the Pilot Proficiency Award Program (see Advisory Circular 61.91H), a pilot can receive refresher training and earn a phase of the "Wings" program that also can be used in lieu of a flight review. It is a classic win-win situation that not only can polish a pilot's rusty techniques; it can also reset the flight review clock for another two years.
Like rusty pilots, aircraft that have sat out the winter can use some tender loving care after being neglected over the cold, winter months. A good check out by their local aviation maintenance technician or at least a very, very, careful preflight would be appreciated by the aircraft. After all, who knows what creatures spent the winter living in the cowling or cabin? Even in early spring, birds also like to build their nests in the tails and wings of aircraft, not to mention exhaust stacks or inside the cowling.
OF SPECIAL PILOTS
Although many pilots and aircraft will need the dust brushed off them and the old motor rewound, there are several groups of pilots that could use some special care and feeding. Because of their unique operating environments, seaplane, helicopter, and agriculture pilots deserve special attention when getting ready for a new operating season--especially if they have not flown much over the winter. Some pilots are lucky. They live or work in the warmer areas of the country where they can maintain their currency year round. Others are not so lucky. For those pilots who had to hibernate over the freezing winter months, the following accident reports should serve as a reminder that seaplane, helicopter, and ag pilots require a greater level of proficiency because of the unique operating capabilities of these type aircraft.
Seaplanes and helicopters share a special operating risk that fixed-wing aircraft don't normally share: Frequent off-airport operations. Yes, we know that many Alaskan and other fixed-wing pilots routinely operate off-airports, particularly those in more remote areas, but we think the majority of fixed-wing pilots operate off some type of designated grass or paved "airport" rather than an unimproved "bush airstrip."
To avoid burying ourselves in controversy, we are referring to any cleared, maintained, or monitored landing area as an airport. We are doing this to contrast a fixed-wing aircraft landing at such an airport with seaplanes and helicopters that can and do frequently land in areas that may not be maintained or monitored frequently like an airport. For example, seaplanes frequently land in rivers and lakes where floating objects such as trees and logs lie in wait for the unwary; submerged objects such as decaying piers and pilings wait to rip open a float or hull; and hidden objects such as sandbars and rocks silently wait beneath the surface to ruin your day. They all pose special risks to seaplanes. Add in the common aviation hazards of trees, power lines, telephone cables, tall towers, and the latest threat to anything that flies--the growing number of cellular telephone towers that keep popping up around the country like mushrooms, plus throw in a few boats and bridges and the hazards of off-airport operations become real for seaplane pilots, posing risks that those who land on paved runways seldom have to think about.
Although most helicopters seldom face submerged piers (some helos do operate on floats), most helos face many of the same risks as seaplanes with a few unique ones of their own. For example, steep slope operations have upset more than one helo trying to land. Add in the dangers of whirling rotor blades and tailrotors, tall grass and brush that the rotors can hit, and off airport landings, and the potential dangers of helicopter operations become more of a concern.
Are we saying that such operations should be prohibited? No. But we are saying that such risks have to be identified and managed through good pilot training, good company operating procedures, and attention to detail. Add in the lack of proficiency of someone who didn't fly much over the winter, and you get someone who could benefit from some refresher training before venturing out into the wild.
And the "wild" may be as near as your local parking lot as one helicopter pilot found out several years ago. According to the incident report, the commercial pilot "made a hard landing while trying to land in parking lot. Lost left pedal effect. Spun 3 times. Entered autorotation."
In another case, the commercial helicopter pilot, "allowed aircraft to drift into outcrop while hovering. Landed in wash. Damaged blade tip." Another commercial pilot, while "surveying flood damage, skid slid under power line. Backed off. Landed to check. Minor damage." Our final helicopter example reported that the pilot "hit wire on takeoff from highway. Air ambulance operation from highway. Landed safely."
These helicopter examples show that because of their ability to operate in confined areas, helos also have some unique operating risks. Nothing that good training can't overcome, but helicopter pilots need to be especially careful when regaining currency and proficiency after a layoff from flying. This is especially true of non-commercial pilots flying helos because they may not have access to the safety information a commercial operator may have, plus pilots flying for commercial operators have to pass recurring proficiency check rides.
Like helo pilots, agriculture pilots also operate in a special environment. Wires and trees around fields pose special risks for them. As reported in the on-line incident data from the FAA's Office of System Safety, the 4,000 hour commercial ag pilot "failed [to] clear wire on pull-up from spray run. Caught on spray pump. Broke a blade. Landed safely." Another ag pilot's report was to the point and very succinct, "During spray runs flew under power lines. On next run hit wire. Wire hit windshield and tail. Returned to base." And since both ag planes and helicopters are involved in ag operations, one 11,000 hour commercial pilot's incident report of an ag helo incident simply said, "Contacted power line at the end of a spray run. Landed safely."
Pilots operate daily in areas with some or many of the risks listed. And they do this safely. The pilots at risk are those who fail to recognize potential risks, or those who ignore them.
For example, seaplane pilots need to remember that whenever a waterway floods, there is always the possibility that trees and other objects may be floating downstream. Flowing water can also create or move sandbars and other natural objects.
AND DIGITAL TV TOWERS
Like a rapidly changing river, low-level helicopter flight paths can change almost overnight. Cellular telephone towers tend to "pop up" along highways that helicopter pilots like to use as low-level flight routes. Add in the low visibility operating capabilities of helicopters, and the new towers become an even greater potential threat.
The latest danger to all low-level flight operations is the new towers being built around the country with the introduction of digital television. Entrepreneurs wanting to cash in on the developing high definition television market are building these new towers in areas that may pose risks to pilots, i.e., landing areas and airports. In some cases, these new towers may not be charted. These new towers are at the center of a controversy between the aviation community, local governments, and the Federal Communications Commission (FCC). At issue is the FCC's desire for these new towers to be installed and the question of whether or not these new structures are subject to local zoning control.
With all of these potential risks, the challenge for aviation is keeping up with all of the changes in the low-level landscape.
Out of the list of potential hazards that seaplane, helicopter, and ag pilots may have to face on a daily basis, two of the most dangerous ones are, arguably, power lines and towers. Low altitude, unmarked power lines pose even a greater threat. Although large power lines are normally charted for their navigational value, such lines pose significant risks for pilots flying low through valleys, mountain passes, and down the center of rivers and other water ways. The problem is not all such lines are marked by the traditional color balls that were designed to make such lines more visible. Because not all lines are marked, and because power lines are difficult to see, pilots must learn to look for parts of the power line system that can be seen such as the towers supporting the wires crossing a river or mountain pass. Once aware of such support towers, pilots then can search for the wires before descending to an altitude where the wires hanging between the towers could pose a threat.
Unknown power lines are not always the threat. Although ag pilots routinely fly near power lines and telephone cables, their risk is different. They normally know the wires are there. Their problem is remembering the wires while maneuvering. Wind, turbulence, blinding sunlight, fatigue, loss of power, and operating on the edge of the aircraft's limitations have all contributed to ag accidents and wires. For pilots who may have to make a last minute decision to fly over or under a set of wires, one misjudgement can result in a potentially fatal wire strike.
The same is true of flying around towers. Like power lines, towers pose a potential threat to low flying aircraft. Add in a tower's support wires for those towers with them, and the danger zone around a tower extends both vertically and horizontally around the tower. The secret is to locate charted towers while flight planning and planning how to safely circumnavigate them or to over fly them.
SO HOW CAN
First, all pilots should operate high enough to comply with the Federal Aviation Regulations minimum altitude requirements. Then all pilots should keep a watchful eye out for towers, power lines, and other such obstacles. Those charted, those not charted, and those not required to be charted. Pilots can also report new tower construction to their local Flight Service Station or local FAA air traffic facility to alert FAA to the tower. Although FAA doesn't have any authority over the construction of towers, FAA can formally object to both local and other federal government organizations that do have authority over such construction and local zoning.
Second, before flying at a low altitude, all pilots should carefully review their appropriate sectional charts for potential threats along their projected flight route. This review needs to include the published chart changes listed in the Aeronautical Chart Bulletin in the appropriate Airport/Facility Directory that have not been added to the published chart. Pilots should also check for any NOTAM that might list a new obstacle. The NOTAM check should also include any airport, navigational, or operational changes for the route and airports along the route at which the pilot may land. The Airport/Facility Directory also contains information about hazards around airports listed.
Finally, a trick that seaplanes and helicopters routinely use is to fly at a safe altitude over the intended point of landing and once they determine that no unknown risks await them, they descend to their respective operating/landing altitude. Helicopter pilots call this making a high reconnaissance.
FAR §91.119, Minimum safe altitudes: General, outlines the minimum altitudes that apply to all aircraft except when necessary for takeoff or landing. The rule states, "Except when necessary for takeoff or landing, no person may operate an aircraft below the following altitudes:
(a) Anywhere. An altitude allowing, if a power unit fails, an emergency landing without undue hazard to persons or property on the surface.
(b) Over congested areas. Over any congested area of a city, town, or settlement, or over any open air assembly of persons, an altitude of 1,000 feet above the highest obstacle within a horizontal radius of 2,000 feet of the aircraft.
(c) Over other than congested areas. An altitude of 500 feet above the surface, except over open water or sparsely populated areas. In those cases, the aircraft may not be operated closer than 500 feet to any person, vessel, vehicle, or structure.
(d) Helicopters. Helicopters may be operated at less than the minimums prescribed in paragraph (b) or (c) of this section if the operation is conducted without hazard to persons or property on the surface. In addition, each person operating a helicopter shall comply with any routes or altitudes specifically prescribed for helicopters by the Administrator."
The key to another safe season of flying is to remember to fly high. There is safety in altitude. But when you have to operate low, first fly high while checking for low altitude dangers, and once you are satisfied that it is safe to descend, go down to the appropriate altitude while remembering the minimum operating rules. Don't let a power line or tall tower ruin your summer.
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