Understanding Air France 447 (24 page)

A pilot needs to understand the airplane, in all its modes. But that level of knowledge, understanding, and insight can be difficult to acquire in a short amount of time. There is a huge volume of material to be assimilated.

Like a surgeon that learns a new procedure, one does not become an instant expert. Once simulator training is complete and the new pilot is certified to fly the airplane, his or her initial experience in the airplane (15-25 hours typically) is with a line instructor, on actual passenger carrying flights. Most of that time is spent in cruise, and on a long-range airplane such as the A330, there will most likely only be a few takeoffs and landings with the instructor present before he is satisfied that the new pilot is “good to go.” But the learning process is far from over.

The new pilot will be restricted slightly in the weather that an approach may be made in, and he will not be authorized to fly with another pilot who also has fewer than 75 hours in the airplane. It will be up to the pilot’s own initiative as to how well he reviews his previous materials, and refreshes his memory of all the material that he had to try and absorb quickly just a few weeks prior.

It can seem overwhelming at first, so much to remember, so much to look for, so much to keep in mind. Until it clicks, and then the airplane is a beautiful friend to fly. But it will take a conscious effort to do it. If one only thinks about the routine functions used on every flight, some of the lesser used functions and nuances can be forgotten.

Everything works so well, so much of the time, that when things are not going right, it is easy to fall into the trap of assuming that the automation is doing the right thing. For example, that anytime the flight directors are on, that they are worth following.

There are red disconnect buttons on the sidestick (for the autopilot) and on the thrust levers (for the autothrust) that give the pilot instant control over the airplane. I have told my students many times, “If it’s not doing what you want it to do, make it do it! Click it off, push it over, make it turn, whatever it is you want to happen,
Make it Happen!
” Of course, you must be thinking far enough ahead of the airplane to know what that is.

The Airline Transport Pilot (ATP) standards for the US dictate that the successful candidate must be the “master of the airplane.” It is not just a skill set, it is also a mind set.

The Final accident report by the BEA states the following as a component of the cause of the accident:

The occurrence of the failure in the context of flight in cruise completely surprised the pilots of flight AF447. The apparent difficulties with airplane handling at high altitude in turbulence led to excessive handling inputs in roll and a sharp nose-up input by the PF. The destabilization that resulted from the climbing flight path and the evolution in the pitch attitude and vertical speed was added to the erroneous airspeed indications and ECAM messages, which did not help with the diagnosis.

The crew, progressively becoming de-structured, likely never understood that it was faced with a “simple” loss of three sources of airspeed information. In the minute that followed the autopilot disconnection, the failure of the attempts to understand the situation and the de-structuring of crew cooperation fed on each other until the total loss of cognitive control of the situation.

The airplane went into a sustained stall, signaled by the stall warning and strong buffet. Despite these persistent symptoms, the crew never understood that they were stalling and consequently never applied a recovery maneuver. The combination of the ergonomics of the warning design, the conditions in which airline pilots are trained and exposed to stalls during their professional training and the process of recurrent training does not generate the expected behavior in any acceptable reliable way.

In its current form, recognizing the stall warning, even associated with buffet, supposes that the crew accords a minimum level of “legitimacy” to it. This then supposes sufficient previous experience of stalls, a minimum of cognitive availability and understanding of the situation, knowledge of the airplane (and its protection modes) and its flight physics. An examination of the current training for airline pilots does not, in general, provide convincing indications of the building and maintenance of the associated skills.

In the absence of reliable speed indication, an understanding of the physics of high altitude flying, gained through training in the fundamental principles of energy conversion, equilibriums of forces, and lift and propulsion ceilings, could have considerably helped the pilots to anticipate the rapid deterioration in their situation and to take the appropriate corrective measure in time: initiate a descent.

The final report theorizes that over-speed was a strong risk in the PF’s mind. I do not disagree, as several statements were made about having a “crazy speed,” and at one point he extended the speed brakes. This was the consequence of the fact that, in theoretical teaching (notably Airline Transport Certificate), the risk of “high speed stall” is presented equally with the more classic “low speed stall”. Though low-speed buffet is quite well known to pilots, excursions beyond maximum speed limits are not demonstrated in training. Furthermore, vibrations (linked to buffet) were erroneously associated with over-speed.

Air France’s Aeronautical Manual describes in great detail, over 38 pages, the physics of high-altitude flight with real cases. This knowledge is also included in the theoretical teaching that is supposed to be provided at an advanced stage in the training of a future airline pilot (Airline Transport License theory, type rating performance). The climbing flight path that was initially more or less deliberate on the part of the crew is likely a clue to the insufficient assimilation of these theoretical notions.

Modern aircraft such as the A330 are far less critical in the transonic range than their earlier generation counterparts. In those airplanes, an over-speed condition could lead to an aft shift of the center of lift, interruption of the airflow over the tail, and an uncontrollable dive, known as Mach tuck.

Unfortunately, the characteristics of exceeding the maximum speeds for particular aircraft types, and therefore the applicable risk for each, are not well known to pilots.

The Future of Training

Training has certainly improved with time, and I am confident it will continue to do so. There are areas that are subject to improvement, and I have no doubt that progress will be made along these lines.

A current threat is that a large amount of time is dedicated to simply learning to operate the particular aircraft and its technology, along with the company’s procedures for the normal and non-normal operations as required. Little time is dedicated to flying skills, which obviously must be the foundation upon which all the procedural and technology training is based.

Pilots come from a wide variety of backgrounds. It is difficult to quantify what actual experience and skill any one pilot has in handling unexpected circumstances where control of the airplane is at stake. Even if a pilot had the experience and skill when he was hired, how well are those skills preserved when flying on the autopilot 99% of the time for decades?

Loss of Control In-flight (LOC-I) remains the leading cause of accidents over the last 20 years. Other accident causal factors have been reduced due to more reliable equipment and systems providing improved protection and recovery from wind shear, traffic, and terrain threats. Yet the LOC-I accident rate remains virtually unimproved and has been assuming an increasing percentage of the cause of fatalities. According to a Boeing study, there were 1493 fatalities due to LOC-I, one due to engine failure, and 225 due to non-power-plant systems failures (less than 1/6 th of the LOC-I rate).
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Yet considerably more time is spent on those failure scenarios then recovery and prevention of loss-of-control events.

In June 2009, coincidentally right after the AF447 accident, the International Committee for Aviation Training in Extended Envelopes’ (ICATEE) group was formed under the Royal Aeronautical Society. The group consisted of more than 80 specialists from around the world. Their goal was to develop improvements in airline pilot training to prevent loss of control accidents in the future.

LOC-I accidents had been highlighted due to several recent high profile crashes: a Colgan Air Bombardier Q400 in Buffalo, NY, and a Turkish 737 crash in Amsterdam, Netherlands. They both occurred in February 2009, and both had been the result of improper pilot action that lead to stalls, though under different circumstances. Though they did not know it at the time the group convened, AF447 is obviously in that same category.

Results from more than three years of work by the group are due to be available in mid 2013, and are said to include a training matrix and an upset prevention and recovery manual. The group identified a list of shortcomings in training, including the limited environment pilots are exposed to in training, simulator realism at the edges of the envelope, g-force awareness, and the ability to create a “startle and surprise” environment in the simulator.

Sunjoo Advani, an aerospace engineer that headed the ICATEE, said, “As it turns out, one of the biggest problems is startle and surprise during unexpected and unforeseen events. LOC exposes [the pilots] in such a way that they have to go from a low state of arousal to a quick an effective response; and those responses can be counterintuitive.” Included in those responses may be such actions as pulling on the yoke (or sidestick) after being startled, even though stall warnings are taking place.

In the case of AF447, we see the crew going from a “low state of arousal” (cruise flight) to the sudden and simultaneous loss of reliable indications, flight director guidance, and autopilot control, combined with no outside visual reference. Bonin’s actions are often described as “inexplicable.” In light of the work of the group seem almost predictable.

Advani said that simulator training can be improved by teaching pilots to recognize and recover at various stages of the development of an upset. “For high-altitude stall training you should not be putting the pilot in the simulator and saying ‘recover.’ Pilots need to recognize the signs, the buffet, the stall warning, the stick pusher, and learn not to fight those systems. These are basics that we have not adequately or consistently trained for.
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”

The training technique improvements are thought to be able to achieve about 75% of the goal in training improvements. The other 25% could be accomplished with improvements in the training devices themselves. The envelope of the simulator should be extended beyond approaching the stall, as the airplane’s actual stall characteristics are not accurately represented in the simulators. The actual airplane’s behavior tends to have a more violent buffet, and be less stable in terms of roll and yaw. One suggested method is the incorporation into simulators of a ‘representative model’ of a transport category aircraft’s stall behavior. While it may not match the individual airplane model’s stall characteristics exactly, it will be far better than the non-data the current simulator behaviors are based on today.

Additional simulator improvements could be functions that provide a clogged pitot scenario, wake turbulence encounter (which can often induce a rapid rolling motion), and other realistic models, in addition to the current menu of wind shear scenarios that modern airline flight simulators offer.

But there are limits to what can be done, even in the most advanced simulator, as it remains bolted to the floor. G-load sensation is difficult or impossible to represent. Some degree of positive g’s and accelerations are achieved by pitching the simulator back, but negative g’s (lightness in the seat), and high accelerations are not possible to create.

To answer these demands, a real airplane can be used, and
is
being used. Aviation Performance Solutions (APS), in Mesa AZ, uses a fleet of aerobatic aircraft to teach upset recovery training. Their clients are largely corporate and private customers, but there has also been some airline interest as well. One curriculum offered by APS involves a multi-day, multi-flight regime. You can practice these maneuvers all day long in a simulator, but it takes on a whole new level when the airplane is pulling down on your seatbelt and objects are floating or flying around the cockpit.

In the aircraft, the trainees feel the real-life forces and cues, experience actual upset attitudes and need to recover. Then they are placed in the simulator again and can compare the best the simulator has to offer with real forces, and make the correlations.

Randall Brooks, in his paper
Loss of Control in Flight, Training Foundations and Solutions
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states:

Although there is no technical challenge in creating a visual scene of a 110° bank attitude with the nose 30° below the horizon, the learning experienced while viewing that scene from the security of a simulator bay has no relation to the knowledge and attitudinal changes received from viewing that very same attitude strapped into an aircraft.

The development and acquisition of skills related to correctly and appropriately responding to the psycho/physiological reactions inherent in confronting undesirable aircraft states is fundamental to executing a safe recovery from an unexpected aircraft upset. The required learning cannot be achieved absent from the consequences faced in actual flight.

What this means is that some training in an aircraft is required to fully prepare a pilot for an aircraft upset encounter.

The addition of airplane training adds some additional risk. But the psychological impact of being in a real airplane in an actual unusual attitude that must be recovered from enhances the training experience, and hopefully its effectiveness. The additional risk is mitigated by specially trained instructors, in a structured training program, in an aircraft suitable for this maneuvering. While the addition of aircraft training will increase the risk for that training, it should increase the safety of airline operations staffed with those trained pilots.