The anniversary of one of the most publicized general aviation accidents ever came and went, and almost on cue the NTSB released its official report on the crash that killed John F. Kennedy Jr. Together, they made a powerful reminder that one of the earliest identifiable pitfalls of flying is still with us today. Aptly named the graveyard spiral, it has taken its toll of lives since the invention of the airplane.
Like its cousin the tailspin, the entry is insidious – resulting from spatial disorientation – and the conclusion is often fatal. The entry pattern associated with either maneuver is similar, but the resultant maneuvering track quite different. Real-life testing and experience, radar tracking tracings and recorded performance distinguish the two.
Radar tracking information included in the NTSB report of the Kennedy accident describes the airplanes ground radar track and performance prior to impact. A review of this information strongly suggests that spatial disorientation, with a resulting graveyard spiral, was the probable cause of the accident.
Some people may wonder how a flight condition that has been known since the Wright brothers can be allowed to continue to take its toll of lives to this very day. The answer is a rather complex one because it involves the laws of aerodynamics and the behavioral characteristics of pilots.
What is more difficult is attempting to explain why pilots, who ought to understand the aerodynamics involved, subordinate their knowledge and trained responses to survival instincts. Surprisingly, it is this succumbing to survival instincts instead of a trained response that contributes to the pilots demise.
Even private pilots receive instruction in, and are tested for, controlling the aircraft solely by reference to flight instruments. Though some would debate the point, the FAA considers the training adequate to enable the pilot to return to visual conditions should they inadvertently become involved in a loss of visual references because of weather.
So, although not qualified as an instrument pilot, newly certificated private pilots ought to be capable of reversing course to withdraw from troublesome weather. The important point is that the successful outcome of the reversal depends on the pilot reacting with a proper (trained) response in the first place.
This is problematic because the pilot needs the discipline to execute the proper response in order to recover, but the survival instinct generally induces a reaction that makes a safe recovery impossible.
We will never know the number of pilots who have successfully recognized and recovered from a graveyard spiral, but we do know the approximate number who did not.
The pilots first defense against becoming a statistic to the graveyard spiral is obviously avoidance. The second defense is to recognize one – despite its insidious nature – and respond to an inadvertent entry with proper corrective action. To effectively exercise both these defenses we must first understand what a spiral is, how such a condition can develop without the cooperation of the pilot, and the proper recovery technique.
Anatomy of a Spiral
The graveyard spiral possesses some rather dramatic dynamics. It begins when pilots attempt to maintain normal flight by reference to visual cues instead of their flight instruments. Then, for whatever reason, the pilot allows the airplane to deviate from its desired flight attitude or altitude without conscious control inputs. In the majority of known instances of inadvertent entries into a spiral, this deviation eventually resulted in a steep bank and rapid turn.
The degree of bank increases as the turn continues. This causes an increase in aerodynamic load factors, loss of altitude, increase in airspeed and rapid rate of descent, and further steepening of the bank.
The steepening of the bank also decreases the radius of turn. Because the inner and outer wings have to arrive at the same point simultaneously, the outer wing must travel faster because of its greater radius and distance of travel. Thus, the outer wing is developing greater lift due to its higher velocity. It is this lift differential that causes the raised outer wing to want to rotate toward the inner wing, thereby increasing the bank.
The ever-steepening bank, higher g forces and decreasing turn radius result in a domino effect, worsening with time. If the pilot attempts to stop the descent and reduce the airspeed by applying nose-up elevator, g forces will increase further and aggravate the domino effect.
Amazingly, all this can occur with or without the cooperation of the pilot, depending upon flight control inputs. To understand this, consider the role of flight control inputs by the pilot in this particular maneuver.
The pilot assumes a reactive rather than proactive role when controlling an airplane solely by reference to flight instruments. The pilot detects a deviation after it has occurred by scanning the flight instruments and noting an uncommanded change. The pilot then reacts by applying flight control inputs to restore the aircraft to its desired attitude, heading or altitude. When flying by visual references, pilots assume a proactive role because they detect and correct changes as they occur.
If the pilot undercontrols during the correction, the airplane will continue to deviate from the desired attitude and the condition will worsen at an accelerating pace. If the effectiveness of the control input is greater than the rate of deviation (overcontrolling), it usually requires a series of control applications in the opposite direction to correct and could cause pilot-induced oscillations. Should the pilots reactive time continue to lag behind the airplanes dynamics, deviation from controlled flight will increase at an accelerating rate.
Either way, the prospects are grim. Either a structural failure could occur or there may not be enough time or altitude to allow recovery before the airplane runs out of altitude.
Pilots recover from incipient spirals just as they complete any other maneuver – through a trained response. The most common response to a spiral is to ignore outside references and bodily sensations. Concentrate on your flight instruments and apply the necessary flight control inputs. The accepted sequence is to level the wings and confirm a zero rate of turn by reference to the turn coordinator, then, as the turn stops, gradually but firmly apply nose-up elevator pressure to stop the descent and reduce airspeed. Conditions permitting, the pilot is reminded to simultaneously reduce power to idle while completing the first two steps. This will aid in reducing rate-of-descent and airspeed.
Once control is regained, most instructors teach pilots to momentarily maintain straight and level flight and then adjust the power and airplane attitude as necessary to attain the desired heading and altitude for continued flight.
The reason the proper procedure is required is fairly straightforward. Leveling the wings first will unload most of the g forces and stop the turn. Application of nose-up elevator as the turn stops will aid in reversing the descent and decreasing the airspeed. Reducing power will initially assist in both reducing the rate of descent and airspeed.
Momentarily flying straight and level will provide pilots with the opportunity to reorient their thinking to normal flight control. It will also help prevent the pilot from immediately pitching up to regain lost altitude, which could result in too great a loss of airspeed and a possible stall/spin entry. At the level-off point the pilot adjusts power and attitude as necessary to return the airplane to a pre-selected altitude and heading.
How You Do It Matters, Too
Performing the steps in the proper order is crucial. Pilots should not attempt to stop a descent while in a steep banked turn by applying nose-up elevator pressure. If the pilot becomes mentally locked into trying to raise the nose, the g forces and the lift differential between the wings will only continue to steepen the bank.
The cumulative effect can make recovery within a few thousand feet of the surface impossible and could overstress the airplane structure to the point of failure.
The problem is that many pilots – primarily VFR pilots but also some instrument pilots – dont apply the aeronautical knowledge they were induced to learn to get their certificates. Those who learn things only in order to pass the written and oral tests may, when the chips are down, subordinate that training to other preconceived priorities. This will hinder and delay pilot recall during the attempted recovery.
New priorities develop as a result of the pilots experience and are influenced by that individuals personality traits. As in all of lifes experiences, the training that one receives becomes more meaningful as experience is gained. This is why it is important that pilots remain focused on their trained responses by periodically practicing various simulated emergency maneuvers and unusual flight attitudes under both visual and simulated instrument conditions.
This repeated practice develops into a desirable personality trait as well as aiding in maintaining a high level of proficiency and immediate recall should the skill be needed.
A finding of pilot error, common in many general aviation accidents, indicates some type of experience or knowledge deficiency, not intent. If accidents occur without the intent of the pilot, then who or what is responsible for them? The answer is quite simple: Human nature is subordinate to Mother Nature.
Examination of the NTSB report indicates that what happened to John-John that night is not a case of negligence or due to his flying a single-engine airplane at night, as had been implied. Instead, it was the result of a low-time pilot being caught in a series of pitfalls because of inexperience, not intent. The fact that he was flying a single-engine airplane at night has little to do with this type of accident. It was the loss of visual references causing confusion of the pilots senses that resulted in the tragedy.
Banishing the Demon
Each aircraft accident is the result of a completed accident chain. A point is reached during a series of uninterrupted negative events where the accident chain is complete and an accident will occur. Should this series of events be interrupted by pilot recognition and corrective actions, the accident will be avoided.
Had this accident happened to the average Joe, it would not have received the same fanfare and level of attention from the media, the industry and the federal agencies involved. Since the principals involved were public figures, an endless number of experts surfaced and, fueled by the medias propensity toward the dramatic, blamed the accident on everything imaginable.
Yet they missed the most newsworthy item of all: They did not question the prevalence of this accidents cause throughout aviation history, and why it is still with us today.
The graveyard spiral is a maneuver we should not have to live with. Its occurrence can be drastically reduced through education, practice and review. Flight techniques for recovering from a spiral must be taught and practiced during initial training and periodically reviewed after certification.
Pilots must acquire a greater understanding of the aerodynamics and pilot behavior characteristics that contribute to the deadly spiral. Pilots must also learn to periodically and objectively review their own personality traits and to correct those having a negative effect upon their own safety.
Assurance that this education takes place rests squarely on the shoulders of those government agencies and aviation organizations responsible for aviation safety, but also upon pilots themselves. Let the tragedy that befell John F. Kennedy, Jr. remind us of the importance of applied aeronautical knowledge and constant practice to avoid aviations many pitfalls.
Also With This Article
Click here to view “Excerpts from the NTSB Report on JFK Jr.s Crash.”
-by Thomas Oneto
Thomas Oneto is a 13,000-hour ATP/CFII, Part 121 and corporate pilot, and former Designated Pilot Examiner.