The Lost Horizon

The search for a cure for spatial disorientation ranges from instruments to instruction


Looking toward the horizon isnt just the province of sailors looking for land or of preteens daydreaming their way through history class.

Pilots use it on virtually every flight to take off and land, certainly, but also to keep the airplane upright. When a natural horizon isnt available, an artificial one inside the cockpit allows pilots on instruments to keep the airplane under control. Basic stuff, certainly, but loss of control due to disorientation remains a leading cause of accidents in aviation.

Anyone with a pulse was inundated by the coverage of the crash of John Kennedy Jr. off Marthas Vineyard in July. Regardless of your opinion of the quality or the saturation of the media coverage, the attention should serve as a reminder that watching the horizon, whether its natural or artificial, is one of the best ways of staying up in the air.

Put another way, not paying attention to the horizon is asking for trouble.

If the JFK coverage revealed nothing else, it showed how willing some aviation experts are to speculate about accident causes. Based on the testimony of a few pilots making the same trip the same night, VFR into IMC was quickly determined, by popular acclaim, as the cause of the crash. When it became clear that the weather reporting stations along the route were showing marginal visual meteorological conditions, the primary theory quickly switched to black hole phenomenon caused by night flight over open water on a nearly moonless night. Thats hairsplitting, perhaps, because both scenarios involve disorientation due to the loss of a visible horizon.

Once the wreckage was recovered, some potential causes of the accident were quickly ruled out. The propeller had not slung a blade, a scenario that could have ripped the engine from its mounts and made the aircraft uncontrollable. The engine was producing power at the time of impact.

Analysis of the vacuum system and autopilot, other potential mechanical causes, is ongoing.

Wheres the Risk?
Whatever the final verdict, non-pilots have been reminded that flight does carry risks. How the pilots cope with and manage those risks remains the subject of debate.

The AOPA Air Safety Foundations annual Nall Report attempts to measure the riskiness of certain kinds of flight by calculating the frequency of different types of accidents. In its 1998 report using 1997 accidents, the ASF counted 38 fatal instances of VFR flight into instrument meteorological conditions and seven fatal IFR flights that resulted from loss of control in IMC.

Nor does the figure change much over time. Aviation Safetys analysis of the NTSBs preliminary reports on accidents from July 1998 to June 1999 counted 25 fatal VFR into IMC accidents and 16 fatal loss of control accidents on IFR flights in IMC. Those 41 crashes, which killed 74 people, accounted for 13.5 percent of all fatal accidents from all causes during that 12-month period.

In addition, there were another 29 accidents that did not result in fatalities, although most involved injuries. Seventeen were VFR into IMC while 12 were disorientation in IMC while on an IFR flight plan. Clearly an instrument rating did not shield the pilot from misfortune.

All told, 70 flights during that period were prematurely terminated due to pilot disorientation while in IMC.

To put that into perspective, however, consider that more than 100 accidents per year result from fuel exhaustion, although they are not as often fatal.

The statistics seem to raise more questions than they answer. Because so many of the accidents involve fatalities, well never know why certain pilots came to grief. We cant know what they saw – or didnt see – from the cockpit when control was lost. We dont know what they felt or what actions they took to try to save the flight.

Disorientation results from a battle between a pilots eyes (visual cues) and his inner ear (vestibular cues). When one sense disagrees with the other, the pilot must choose which one to believe. Even then, the conflicting information can lead to vertigo.

The problem arises in flight when the aircraft rolls slowly, below the threshold of the vestibular systems ability to sense it. If the pilots attention is diverted, as in looking at a chart, he will find the attitude indicator showing an unexpected position when he looks back. That sets up a conflict between the vestibular system, which says the airplane is straight and level, and the eyes, which detect the bank.

If the pilot then makes a sharp control movement to correct the bank as indicated on the attitude indicator, he will feel as if he is rotating into a bank rather than out of one. The vestibular system can be so compelling that he will reverse his control inputs in order to accommodate the vestibular sensations.

Although the Kennedy crash started the discussion, it did not end there. General media types solved the problem by proposing instrument and night training for private pilots, both of which already are required. Those within the industry also received a wakeup call, however. Discussions about instrument design and more rigorous training standards took on new life.

Perhaps the least surprised by the call to arms was Stanley Roscoe, a professor of aviation and engineering psychology and former head of Display Systems for Hughes Aircraft Co. Roscoe has been researching cockpit instruments for more than 50 years and has concluded that modern instrumentation is anything but.

In a landmark study in 1954, 20 University of Illinois student pilots were given the task of making a 180-degree turn in a simulator without outside visual references and with the attitude indicator covered. Nineteen of them went into a graveyard spiral. The other suffered a whip stall and then a spiral, but researchers classified it as a spin. In a real airplane, all would have died.

Roscoes research has concluded that VFR pilots get disoriented after the airplane slowly banks when visual references are lost. The pilot, untrained in the use of the attitude indicator, discovers the bank and attempts to recover by leveling the artificial horizon bar – exactly the opposite input needed to level the airplane. This horizon control reversal confuses the pilot even further, which makes recovery impossible.

The term pilot error is misused when such errors can be prevented by an experimentally proven equipment modification, Roscoe says.

Its relatively easy to learn the proper control inputs to cope with what Roscoe calls a flaw in the design of the attitude indicator, but fixing the design to make it more intuitive is also easy. By allowing the little airplane in the AI to reflect the aileron position, the pilot intuitively rolls the airplane in the proper direction. In light planes, the modification would be straightforward, involving attaching a sensor to the yoke.

In the case of flight attitude control, all that is needed is to cause the little airplane symbol on the artificial horizon indicator to rotate in direct response to aileron control inputs, Roscoe says. Thus, to return to a wings-level attitude, the pilot merely has to align the airplane symbol with the displaced horizon bar and maintain that alignment as the real airplane and the artificial horizon bar, rotating in opposite directions, return to wings-level.

Inside-Out Vs. Outside-In
Not everyone agrees, however. To some experts the traditional notion of the artificial horizon accurately representing the outside world and the little airplane representing the fixed wings around the cockpit remains the most sensible.

Theres always been a controversy over the inside-out or outside-in presentation, and when theres controversy the tendency is to stay with the status quo, says Roscoe, who now heads Illiana Aviation Sciences Ltd. and is senior vice president of Aero Innovation Inc.

Glass cockpits on large airplanes and the promise that such technology eventually will work its way into general aviation airplanes has some researchers attempting to throw out the whole notion of artificial horizons.

NASAs AGATE program, for example, is investigating alternative ways of rendering attitude and flight path information. Dubbed Highway in the Sky, the program aims to determine through experimental testing which methods of aircraft control are the easiest – and therefore the safest – for pilots to use correctly.

So far, the front runner is a display that uses concentric boxes to show the flight path stretching into the distance. In addition, the optimal path through the boxes is indicated by a little airplane symbol, and the path of the airplane based on current control inputs is marked by a green dot. Lining up the green dot with the little airplane ensures airplane is following its desired flight path.

Instruments and Instruction
Of course, better instruments wont help if the pilots are merely ignoring the basic airmanship that VFR flying demands, and thats where calls for increasing training requirements come in. Within days of the Kennedy accident, the FAA reportedly was feeling the heat to do something about night and instrument training.

One source inside Transport Canada said FAA officials had begun making quiet inquiries into the details of Canadas night flight endorsement program. Canada allows night flight, but only if the pilot has the proper endorsement, which must be periodically renewed.

Until a couple of years ago, U.S. private pilot certification allowed pilots to forego night training, which would result in a restriction being placed on their certificate that prohibited night flight. By then receiving training similar to Canadas night flight endorsement, the restriction could be removed.

An FAA spokesman dismissed the notion that changes were afoot, saying the FAA wouldnt need to contact Transport Canada to get the details, since theyre probably already available in Washington anyway.

In addition, he said, The current regulations were revised only two years ago after quite a bit of public discussion. To suggest that were thinking of changing things is a little premature.

However, regulation is frequently a political animal. In 1972, the loss of U.S. Rep. Hale Boggs during a flight in Alaska prompted Congress to mandate the installation of emergency locator transmitters. The early models were rushed to market and proved unreliable at best.

Even now ELTs operate in only 24 percent of crashes. The false alarm rate is so high – at about 97 percent of activations – that many countries are threatening to stop monitoring the satellite frequency.

Even the U.S. Supreme Court has said that safe is not the equivalent of risk-free. VFR flying by VFR pilots is a liberating experience, but some such pilots appear to need reminders that they are still pilot in command. And with that command comes the responsibility of ensuring a safe conclusion of the flight.

That may mean additional training or a more capable aircraft. It may mean changing flight plans or even staying on the ground. VFR into IMC is just one of the symptoms of the illness.

The true diagnosis is poor decision making by someone who should know better.

Also With This Article
Click here to view “178 Seconds to Live.”
Click here to view “Preliminary Report: The Kennedy Crash.”
Click here to view “A Better Mousetrap?”


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