You Want a Helicopter, But Can You Fly It?
To the uninitiated fixed-wing pilot, it is tempting to think that hovering a helicopter would be easy. Plenty of fixed-wing colleagues have said (in a tone of voice that indicated their self-rated expertise in aerodynamics), “It can’t be that hard just holding a helicopter motionless.” (Apologies for not warning my rotorhead buddies who are rolling off their chairs in laughter.) I could provide an explanation of why holding a helicopter steady in a hover is aerodynamically difficult, but the explanation would require pages explaining the fundamental aerodynamic differences between an airplane and helicopter. Instead, the most effective way to illustrate how helicopter flying is vastly different from fixed-wing flying is to take an introductory flight lesson in a helicopter. Don’t feel ashamed if you can’t hold the helicopter steady for more than a couple of seconds before the instructor needs to take the controls. Your first 15 flight hours learning how to hover will be spent in a protective area the size of a football field.
Robinson Helicopter Co. provides Safety Notices regarding the role of negative habit transfer for fixed-wing pilots who transition into helicopters. “The ingrained reactions of an experienced airplane pilot can be deadly when flying a helicopter. The airplane pilot may fly the helicopter well when doing normal maneuvers under ordinary conditions when there is time to think about the proper control response. But when required to react suddenly under unexpected circumstances, he may revert to his airplane reactions and commit a fatal error. Under those conditions, his hands and feet move purely by reaction without conscious thought. Those reactions may well be based on his greater experience, i.e., the reactions developed flying airplanes.”
Robinson’s Safety Notice # SN-29, “Airplane Pilots High Risk When Flying Helicopters” (revised June 1994), provides a number of examples. For example, an airplane pilot’s response to a stall-warning horn would be to immediately push forward on the yoke/stick and add power. In a helicopter, the application of forward cyclic would decrease the main rotor rpm even lower, to the point of inducing a rotor stall. In less than 1 sec. the pilot could stall the rotor, causing the helicopter to fall out of the sky. A rapid forward movement of the cyclic can also cause a low “G” condition leading to mast bumping, resulting in the rotor shaft or one blade striking the fuselage.
Another situation in which a dual-rated pilot might react inappropriately is during a retreating blade stall. The flight conditions that tend to create this situation include high forward speed, low rpm, hot-high-heavy, turbulent air and/or abrupt turns. The angle of attack on the retreating blade will exceed the critical AOA, resulting in an abrupt roll into the retreating blade side. It may be accompanied by a low-frequency vibration (an abnormal two per revolution vibration in a two-blade rotor) along with a nose-up pitch. How would a pilot with a predominantly fixed-wing background react to the rapid roll? It would be normal to counter the abrupt roll by moving the cyclic quickly to the opposite direction of the roll. This, however, would deepen the retreating blade stall. The recommended corrective action is to lower collective, increase rpm, reduce forward speed with aft cyclic and minimize maneuvering.https://aviationweek.com/business-aviation/aircraft-propulsion/so-you-think-you-want-helicopter
Add-On Training’s Gaping Holes
There are key missing ingredients in the “add on” training process. For example, most flight schools have policies and procedures that focus on minimizing risk in the training environment. Thus your exposure to weather will be (properly) constrained, as well as off-site landings. This means that you aren’t likely to be exposed to a helicopter’s limited weather capabilities including high winds, rain and icing. The flight school’s recommended off-site landing zones for practicing slope and pinnacle landings will be fairly benign. And by the way, during the training process for a private or commercial helicopter rating, it is entirely likely that you will never practice an autorotation to the ground.
There is minimal exposure to the plethora of unique human factors in rotorcraft flying. In the expedited process to get the helicopter rating you may not get adequate exposure to the challenges of hovering in poor visibility conditions, or worse, on a dark ramp. Maneuvering a helicopter is especially dependent on having a rich visual field to gauge the tiniest of motions for a precise hover or hover-taxi.
You aren’t likely to be exposed to the important issues concerning cockpit ergonomics that can affect your safety, health and performance. For instance, occupants of helicopters are exposed to “whole body vibration.” This can affect the ability of your eyes to see the instruments and the smoothness of your hand motions on the sensitive flight controls, and can cause degenerative wear in the discs of your back and neck.
Another concern of transitioning from fixed- to rotary-wing flying is the lack of training and experience to sense the slightest variation in vibrations that provide subtle but important signals of a component that needs to be properly inspected. Additionally, the quick “add on” process isn’t likely to train us in understanding whether a slight irregular sound or vibration means that we should head toward an airport or do an emergency landing because failure is imminent.
This is just a short list of the many aspects of real-world helicopter operations that you won’t be exposed to during the “add on” training process. Lengthy books have been written about the unique human factors of helicopter operations. In summary, it isn’t an exaggeration to state that helicopter operations are “an entirely different world” from fixed-wing flying, and the add-on process is just a bare minimum to show proficiency in handling a helicopter in the prescribed maneuvers in a strictly controlled training and testing environment.
Proficiency Training in Emergency Procedures
Another large difference between fixed- and rotary-wing flying is the aircraft’s reaction to a mechanical failure of a critical component. The flight control systems of a fixed-wing aircraft are much simpler, with fewer moving parts, than a rotorcraft. In general, the redundancy and relative simplicity of fixed-wing flight control systems means that malfunctions seldom occur and do not require exceptional skill for the flight crew. In contrast, when an important component fails within a helicopter’s flight control system, instant and proper reactions may be needed or else the helicopter can quickly enter into significant gyrations.
Many helicopter emergency procedures require complex “perceptual motor skills,” meaning that muscular movement is required as well as sensory control. Inexperienced pilots who are most in need of a safe training environment in which to make the many repetitions necessary to obtain the proper perceptual motor skills could benefit from access to flight training devices.
Helicopter owners and operators must keep their pilots proficient in helicopter emergency procedures. Should the in-house helicopter be used for this training? In many cases insurance companies have clauses nullifying coverage if damage occurs during training. Then there are the practical considerations like “what if something goes wrong” during the practice? Your damaged helicopter could be in the shop a long time for the repairs. The risk of damage from a small “slip” in technique can be significant.
The NTSB Safety Alert titled “Safety Through Helicopter Simulators” points out that improper performance of emergency procedures has led to numerous helicopter accidents. Deteriorating weather, helicopter limitations and performance characteristics restrict what scenarios can be performed in flight. During flight training, it is difficult to recreate the element of surprise and the realistic, complex scenarios that pilots may experience during an emergency. “Consistent, standardized simulator training will help prepare pilots for the unexpected and will decrease the risk of an accident,” the Safety Alert says.
The value of a simulator for training of critical procedures is unquestioned. The downside is that sending an organization’s pilots to that training requires the financial commitment to take them off the work schedule and provide travel, per diem and tuition.
Before you leap into this considerable investment, be advised of some other limitations. You may have a large parking lot at your factory that you think would be an ideal location for a helipad. It may be, but with a lot of caveats. Don’t believe that a simple concrete pad is sufficient for a helipad. There are multitudes of important factors that must be considered. Some deal with zoning. Some deal with the practical necessity to have clear arrival and departure paths. Others deal with lighting and proper markings. Or how about snow removal? Just to give you an example of the complexity of this topic, you might be tempted to toss rock salt onto your helipad to help deice the surface. That is unwise, especially for a skid-equipped aircraft because it will expose your skids to a highly corrosive substance.
Another example is the site selection for a wind sock. Some might think that the placement of a wind sock is a simple process. It is just the opposite. I once had the incredible learning experience of working with Dr. Thomas Corke of the University of Notre Dame’s Department of Engineering on a helicopter site evaluation atop a high-rise building in an urban setting. Wind currents around adjacent buildings create significant zones of eddies and reversed flow that could cause a wind sock to flow in opposite directions from the prevailing wind. Dr. Corke showed us pictures of nearly 20 wind socks mounted at varying positions around the rooftop helipad; each of the wind socks was pointing in a different direction. Having accurate information of the wind at a helipad is absolutely vital, as the complexities caused by air flowing around obstacles, nearby buildings and/or elevated helipads is far more complicated that many pilots understand.
Helicopter operations inevitably spark noise complaints, and noise is probably the leading reason that attempts to build more heliports are stymied. This topic will require considerable attention if you are serious about implementing a helicopter that will operate at a site other than an established airport or heliport. (For further information about the complex issues involving helicopter noise, see “Center of Attention: London Heliport” [BCA, October 2014] and “Managing Helicopter Noise” [BCA, March 2015].)
You might think that a helicopter can land (nearly) anywhere. This is one of the great misunderstandings about helicopters. The issue is complex because each municipality may have its own laws governing whether a helicopter can land within its jurisdiction. Then there are the practical aspects of landing on unprepared surfaces. There are human factors galore regarding visual illusions when assessing the suitability of an off-airport, unprepared surface for a landing.
We will follow up on these important topics so that you can begin a deliberate process to weigh the pros and cons as well as valuing the necessity to obtain true helicopter experts.
Your time is valuable. Instead of sitting in traffic, you can be productive, which translates into positive ROI. If owning or operating a helicopter makes business sense, then it may be worth it…with the assumption that you involve rotorcraft experts to help mentor you through the long learning process.
Editor’s Note: The first part of this article discussed cost and insurance considerations for introducing a helicopter into your fleet.