VIVAERO
Pilots hostage to automation
The intense use of automation in the cockpit has degraded manual piloting skills. The solution must be addressed through airline training and operational policies.
Transport aircraft are increasingly automated. A modern passenger jet has automatic pilot (AP) systems, automatic engine throttle control (AT), and computerized flight management systems (FMS). In a conventional flight profile, the pilot acts directly on the controls for less than five minutes—half during takeoff and half during landing. Sometimes even less time when the aircraft is equipped with automatic landing systems.
Consequently, there is growing concern that pilots are losing the ability to react manually when automated systems fail or when the onboard computers are programmed incorrectly. Several events have suggested this dependence on automation, such as the one that occurred with a Boeing 757 in 2003.
The aircraft began its descent, preparing for an instrument landing approach (ILS). The Boeing was vectored by the controls to intercept the localizer's course. The aircraft slowed to 220 knots (KIAS), and the captain selected "Approach" mode on the autopilot's Mode Control Panel (MCP). The aircraft was then cleared to descend to 2,500 feet, and the captain entered that altitude into the MCP.
When the aircraft intercepted the localizer's course, it was above the ILS ramp. The captain, realizing that the AP would not be able to intercept the approach ramp, disconnected the system and resumed manual piloting. Shortly thereafter, he lost ILS indications on his instruments. With the aircraft off the ramp, the flaps not in the correct landing configuration, and the ILS signal lost under instrument flight conditions (IMC), a go-around was the recommended procedure.
The captain pulled back on the stick until the attitude was 20 degrees above the horizon. The AT engaged, adjusting the throttles to full power, and the aircraft began to climb. However, because the go-around procedure had been initiated very close to the altitude selected on the MCP, the system switched to Altitude Capture mode, and the Flight Director (FWD) indicated guidance to level off at 2,500 feet.
In manual pilot mode, the aircraft exceeded the selected altitude, and the FWD began to indicate a descent to return to the selected altitude. Climbing now at 25 degrees pitch, in a landing configuration, the speed dropped rapidly. When the Boeing reached 137 knots, the captain brought the stick to the nose-down stop and reduced the engines to idle. The massive jet assumed a 49-degree nose-down position.
The speed increased rapidly in the descent, and as it approached the ground, the GPWS alarm began to sound. The copilot intervened, and both crew members slammed on the pitch-up controls. With a load factor of 3.6 g, the Boeing avoided collision with the ground by just 320 feet.
The event lasted less than 90 seconds, from loss of control to recovery. At the time, no one understood exactly what happened or why, but the 75 passengers and seven crew members were terrified by the experience, which narrowly avoided catastrophe.
Subsequent analysis revealed a pilot conflicted between the attitude he should have maintained and the Flight Director's guidance instructions. The captain stated that he was looking at the screens in front of him and did not recognize the aircraft's condition. Initially, at the top of the maneuver, he assumed the plane was stalling. Later, during the run-up, he stated that he had never seen an attitude indicator show only "ground" and had difficulty reacting.
Apparently, the pilot had lost the ability to manually perform a simple procedure like a go-around in IMC. He had no control over the aircraft's attitude, power, or configuration. He also failed to command the flaps or landing gear to retract. His instrument cross-checks were slow, and his command responses were consistently about ten seconds behind the aircraft's.
His performance was inadequate, despite being a qualified pilot who had completed the required airline pilot training. However, the most significant thing is that this was not an isolated incident.
Three years earlier, in the Persian Gulf, an Airbus A320 lost control during a nighttime go-around, also due to the pilot's lack of manual flight skills, resulting in the death of all 143 occupants and the total loss of the aircraft. Recently, in May of this year, another Airbus A320, during a manual go-around in IMC in Russia, had a loss of control attributed to pilot error and collided with the ground, killing all 113 occupants.
These events join several other accidents worldwide, in which the degradation of piloting skills in the operation of automated aircraft appears to be a contributing factor.
Indeed, airlines emphasize the use of automation as long as possible, as automation flies better than humans in maneuver precision and fuel economy. The downside of this policy is that it produces a pilot who only knows how to fly by following the Flight Director and who rarely looks at the attitude and performance information provided by other instruments.
Everything is fine if the flight proceeds normally and the data fed to the Autopilot is correct. Unfortunately, the programming in the MCP and FMS are the first items to be affected in situations of high workload, distraction, stress, and confusion.
We seem to be forgetting that, regardless of an aircraft's level of automation, piloting involves two basic parameters: attitude and thrust. These two factors define any flight regime.
It's been this way since the first flight of the heavier-than-air aircraft. The fact that we're flying electronic aircraft doesn't change the basic mechanics of flight or the need to control attitude and thrust. When a conflict arises over what the aircraft is doing in automatic mode, there's only one response: revert to basic piloting, referencing attitude and thrust.
This concept could have saved another Boeing 757 in 1996. The aircraft had just come out of a wash, and ground crews had placed tape over the static plugs as protection during service. During the pre-flight inspection, the crew failed to view the tapes, and when the jet took off that night with 61 passengers, the pilots noticed a serious error in the altitude and speed instruments.
Although it was possible to control the plane manually, the autopilot and engine thrust computers lacked the data to function properly. Flying over the sea at night, the crew received conflicting information, such as the stall warning (stick shaker) activating simultaneously with the overspeed alarm.
They could not accurately determine their speed or altitude, even though the artificial horizon and engine instruments were operational. After 28 minutes of intense confusion in the cockpit, the Boeing crashed into the sea at 300 knots, leaving no survivors. The plane could have been controlled if the concepts of attitude and thrust had been applied.
Perhaps all pilots should memorize some attitude and thrust combinations to ensure flight in the event of an anomaly.
As with attitude control failures, thrust control failure was a critical factor in other incidents.
For example, there is a practice of planning takeoffs by inputting higher-than-actual ambient temperature information into flight computers. This causes engine thrust to be reduced during takeoff, thus preserving engine life and saving money. It is a common and approved procedure in commercial aviation, provided certain parameters are observed.
But the three cases below drew attention to the crew's performance:
In January 2000, an Airbus A310 taking off with reduced thrust experienced a stall alarm shortly after leaving the ground.
In March 2003, due to a weight calculation error, the captain of a Boeing 747 rotated approximately 33 knots below the predicted speed, dragged the tail on the ground, and took off with the stick shaker activated. In October 2004, another Boeing 747 failed to accelerate sufficiently during its takeoff roll, overshot the end of the runway, and was completely destroyed.
These three takeoffs were planned with reduced thrust; the aircraft did not perform as expected, and in none of the cases did the pilots advance the throttles to obtain maximum thrust. In all three cases, although the initial adjustment was inadequate, there was enough power available for the aircraft to fly.
Why, then, did the pilots not advance the throttles? Was it a case of extreme adherence to the manuals or simply a failure to apply basic piloting concepts?
What should be clear from this set of events is that humans develop skill in what they practice, but also forget what they don't practice. The scenario of operating automated aircraft may be leading to a degradation of piloting skills, which will often be required in emergency situations.
Solutions include recurring training, company policies, and oversight by aviation authorities. Training today places a strong emphasis on automation, perhaps because it assumes that basic piloting is guaranteed by the crew member's previous experience.
Wrong. Training must necessarily include manual flight and automation-induced failures. Accidents constantly demonstrate this need. As an additional solution, some companies advise pilots to practice approaches at three different levels of automation. Most of the time, they should use automated systems for reasons of economy and precision, but a small percentage of approaches should be done manually, with and without guidance from the Flight Director.
Study after study proves the need for pilots to practice the basics, as the same causal factors emerge with each accident investigation.
Therefore, aviators need to encourage the maintenance of the flying skills they mastered when they received their pilot's license. Automation is an irreversible reality, bringing invaluable advances to aviation safety and efficiency. However, its complexity can also lead to confusion.
When this happens, the recommendation is to revert to manual piloting and regain control of the aircraft. This solution necessarily involves basic piloting skills.
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