Features

May 2019 Issue




Lessons Not Learned

Pilots have succumbed to spatial disorientation for more than a century, despite generations of successive improvements to their aircraft. Why canít we fix this?

On December 29, 2016, a Cessna 525C Citation CJ4 crashed into Lake Erie less than a minute and a half after taking off from Cleveland’s Burke Lakefront Airport, killing all six on board. The NTSB eventually concluded that the pilot became disoriented climbing into low clouds over the lake on a dark night.

The accident occurred nine years almost to the day after an 18,600-hour airline transport pilot flew a Beech Baron into the lake just after departing from the same airport on a nighttime positioning flight. In the case of the Citation, the Board surmised that due to the pilot’s recent transition from a Citation Mustang with a different panel layout, he might have been unaware that he’d never engaged the autopilot as he’d presumably intended. On the night of the Baron accident, ceilings were 25,000 feet and visibility unrestricted, but the moon and city lights were behind the pilot once he turned north over the lake.

These are just two recent examples demonstrating that properly qualified pilots in aircraft equipped with full IFR panels and capable autopilots still lose track of which side is up. Spatial disorientation has plagued pilots since World War I combatants first tried ducking in and out of clouds to evade their opponents, and despite progressive refinements in equipment and training it shows little sign of fading away. How has the accumulated experience of more than a century failed to solve this problem?

Yaw Strings Not the Answer

Accident probable causes in the earliest days of aerial combat were often hard to categorize, but weather hazards came into sharp focus after the U.S. Post Office contracted with the Army Signal Corps to develop scheduled airmail service. Postal officials were determined to prove that deliveries could be made on schedule in all seasons and all weather, and Army officers had little patience with pilots’ concerns about niceties like ceilings and visibility.

The pressure to fly no matter what (sound familiar?) led many early mail pilots to learn the hard way that they couldn’t rely on their senses to keep them right-side-up in the clouds. At least 34 were killed in the first eight years, leading to the grim joke that the life expectancy of an airmail pilot was “about six weeks.” To avoid loss of visual references, those dispatched into low weather went to extreme lengths to maintain ground contact. Mail service pioneer Jack Knight remembered flying over the Allegheny Mountains in 1919 this way:

“Deep gullies and high hills heavily timbered made fog flying a very risky touchy affair. Flying at 30 to 50 feet with never over 100 feet forward visibility in the average fog—made a great many angels out of good pilots. Rushing through this murk at 100 M.P.H. Suddenly a wooded hillside looms up—just about 1/10 of a second of indecision and it’s just too bad.”

Later in the same collection of notes, now in the archives of the Smithsonian Air and Space Museum, Knight recalls a particularly bad day that left him “Pushing forward at 100 mph through murky damp fog—just clearing house tops—brushing thru tree tops, finally after ten minutes of this I began to lose sight of ground although my wing tip had been practically even with the insulators along a telephone line.”

Little wonder that early pilots tried to find some trick that would enable them to at least keep the wings level and hold a compass heading while climbing above any known obstructions (and hoping to find a break to get back down before the gas ran out, another adventure Knight described in harrowing detail). Unfortunately, nothing available actually worked. Weighted strings tied to the struts obeyed the laws of physics rather than the pilots’ expectations and pointed outward along the radius of the turn rather than toward the Earth, making a well-coordinated graveyard spiral indistinguishable from “straight and level.”

Technology to the Rescue!

The invention of gyroscopic attitude instruments in the 1920s finally made it possible for a properly trained pilot to be certain of the airplane’s orientation regardless of visibility outside the cabin. Jimmy Doolittle’s pioneering 1929 “blind flight” proved the feasibility of both aviating and navigating entirely by instrument references, but this advance was slow to filter through to owner-flown aircraft. It would be decades before manufacturers routinely equipped light civilian aircraft with attitude and heading indicators, and the ground-based infrastructure of navigational aids—starting with four-course ranges and non-directional beacons—likewise had to be built up over the course of years. Cub, Luscombe and Taylorcraft owners were left just about where they had been before.

And flying that era’s instrument procedures required proficiency and stamina most 21st-century pilots would be hard put to imagine, much less match. A late-1930s lesson plan for teaching a four-course approach begins with a series of 90-degree legs to determine which side of the airport the airplane is on, followed by a track inbound to find the station (identified by the “cone of silence”), then outbound along the appropriate course to make a procedure turn and reintercept the final approach course—all flown by hand, of course, while listening for the steady tone in the headphones to deteriorate into Morse code “A” or “N” to detect lateral deviations. Changes in volume indicated whether the ship was flying to or from the station.

Four-course approaches could have minimum descent altitudes as low as 300 feet agl without vertical guidance and typically used the cone of silence over the transmitters’ 134-foot-high antenna farm as the missed approach point, making an approach to minimums a delicate business indeed. Even instrument practice required plenty of patience and lots of fuel, not to mention mental gymnastics. Veteran four-course pilots viewed the VOR and panel-mounted CDIs much as a later generation saw the introduction of GPS: so much easier that it almost seemed like cheating.

Even More Technology

Flash forward to the mid-1960s, halfway through that century since the end of WWI. A robust network of VORs defined a system of Federal airways and supported instrument approach procedures to even small rural airports. Most towered fields gained ILS facilities. Manufacturers now offered at least basic IFR panels as either standard equipment or popular options, even on four-place piston singles. Airplanes as inexpensive as the 1967 Piper Arrow sported standard packages that included localizer and glideslope receivers with dedicated CDIs and autopilots capable of holding headings and tracking nav inputs.

The continued increase in spatial disorientation accidents was primarily driven by the rapid expansion of the entire GA sector, which produced more accidents of every description. But other aspects marked the themes that still characterize this particular species of aeronautical mayhem. Owning the equipment doesn’t automatically impart the ability to use it. Earning the rating doesn’t buy much if those skills aren’t maintained.

Otherwise-competent instrument pilots don’t always transition successfully from descent to climb when commencing a missed approach. And the instinct to muscle the aircraft away from trouble tends to overwhelm any calculated appraisal of the resources available in the cockpit. In recent decades, most airplanes lost to spatial disorientation had autopilots that were never engaged.

Glass Hasn’t Saved Us

After decades of stability, the avionics industry was upended twice in less than 10 years. In 1994, the FAA certified the first panel-mount GPS for use under IFR. Despite relatively high installation costs, GPS rapidly became pilots’ navigational technology of choice. Manufacturers responded by developing ever-expanding feature lists, integrating GPS navigators with VHF nav/comms and equipping them with ever larger, brighter displays including detailed moving maps and weather overlays. And in just three years, from 2002 to 2005, the standard panel configuration of almost all new light-airplane production shifted from analog gyroscopic attitude instruments to electronic flight displays. The speed of the change strongly suggests that it was driven by market pressures rather than any demonstrated safety advantage.

In fact, the initial accident record of glass-cockpit airplanes was not demonstrably better than that of conventionally instrumented examples of the same models. There are reasons. Lack of standardization between platforms requires far more intensive transition training: While a KX-170B works pretty much like a Narco MK-12, moving from an Avidyne Entegra to a Garmin G1000 means learning an elaborate and entirely different system architecture. Maintaining real-world proficiency thus requires more consistent recurrent training than many owners expect. And marketing campaigns emphasizing cross-country performance arguably led some buyers to attempt flights that demanded airmanship beyond their own abilities.

Even the apparently obvious advantage of an airframe parachute was slow to realize its potential (see sidebar, “To Pull or Not to Pull?” on the opposite page). If you’re reading between the lines, you may have detected a pattern: Improved capabilities almost automatically translate into attempts to expand the envelope. If you think drivers follow more closely since the introduction of anti-lock brakes, well, the data back you up. There’s strong evidence that individual risk tolerance doesn’t change much: Potential safety improvements are viewed as opportunities to do more within the same margins rather than ways to reduce hazards most pilots already found acceptable.

Spatial disorientation occurs because humans can’t fly: Our sensory apparatus simply isn’t designed for the task, so we are susceptible to long lists of physiological and optical illusions that regularly lead to not knowing which side is up. We can’t physically change ourselves to overcome these limitations, so we’ve tried modifying the conditions of the test with technology and training. As we develop tools to at least minimize spatial disorientation leading to loss of control, we actually have found new and inventive ways to cause it.

One thing that might help is making smooth, gentle, coordinated control inputs. Grip the control with the thumb and forefinger, not with both hands as shown at right. According to the FAA’s†Instrument Flying Handbook, FAA-H-8083-25B, “When flying in IMC, a pilot should avoid making large attitude changes in order to avoid loss of aircraft control and spatial disorientation.” —J.B.

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