Midterm Examination Use your own paper to answer these questions. Please be sure to number your answers and to put your name on each sheet of paper that you use.
What are the two main components of the vestibular system? (2)
A sudden increase in forward motion (e.g., from a catapult launch) can cause a pilot to feel that The Head-Up Illusion involves a sudden forward linear acceleration during level flight where the pilot perceives the illusion that the nose of the aircraft is pitching up. The pilot’s response to this illusion would be to push the yolk or the stick forward to pitch the nose of the aircraft down. A night take-off from a well-lit airport into a totally dark sky (black hole) or a catapult take-off from an aircraft carrier can also lead to this illusion, and could result in a crash. (1)
A sudden decrease in forward motion (e.g., from suddenly deploying the flaps or speed brakes or quickly leveling off) can cause a pilot to feel that:
The Head-Down Illusion involves a sudden linear deceleration (air braking, lowering flaps, decreasing engine power) during level flight where the pilot perceives the illusion that the nose of the aircraft is pitching down. The pilot’s response to this illusion would be to pitch the nose of the aircraft up. If this illusion occurs during a low-speed final approach, the pilot could stall the aircraft. (1)
Why do pilots not get “the leans” when they can see the ground?
The Leans. This is the most common illusion during flight and is caused by a sudden return to level flight following a gradual and prolonged turn that went unnoticed by the pilot. The reason a pilot can be unaware of such a gradual turn is that human exposure to a rotational acceleration of 2 degrees per second or lower is below the detection threshold of the semicircular canals. Leveling the wings after such a turn may cause an illusion that the aircraft is banking in the opposite direction. In response to such an illusion, a pilot may lean in the direction of the original turn in a corrective attempt to regain the perception of a correct vertical posture. In general, the information from the visual system will dominate vestibular sensations (e.g., when you watch a movie with a “roller-coaster” scene in it and “feel” the sensations without moving). (3)
What is the Coriolis illusion? Why is it so difficult to stop?
The Coriolis Illusion involves the simultaneous stimulation of two semicircular canals and is associated with a sudden tilting (forward or backwards) of the pilot’s head while the aircraft is turning. This can occur when you tilt you head down (to look at an approach chart or to write a note on your knee pad), or tilt it up (to look at an overhead instrument or switch) or tilt it sideways. This produces an almost unbearable sensation that the aircraft is rolling, pitching, and yawing all at the same time, which can be compared with the sensation of rolling down on a hillside. This illusion can make the pilot quickly become disoriented and lose control of the aircraft. The connections between the vestibular system and the brain occur at such a low level that they are difficult to “override” with higher cognitive processes (e.g., “self-talk”). However, visual information will generally override these sensations. (3)
Pilots approaching a narrow runway may think that they are too ___ while pilots approaching a runway that slopes up may think that they are too ___. (2)
List the factors that influence depth perception and give a short definition of each. (6)
–Convergence: the degree to which the eyes must move towards each other to focus on objects at different distances. Objects that are farther away require less convergence.
–Binocular Disparity: the degree to which the view from one eye differs from the view from the other eye. The closer the object, the greater the binocular disparity in position in the visual scene.
–Parallax: The degree to which objects appear to move relative to objects farther away as the observer moves.
–Size constancy: objects that are farther away subtend smaller visual angles.
–Brightness: objects that are farther away are usually dimmer.
–Direct perception of gradients: objects, texture of terrain, etc., appear to flow past a moving observer in different patterns depending on their distance and the relative direction of motion.
According to Wickens, aviation tasks can be categorized into four groups. What are they? (4)
Aviate, Navigate, Communicate, Systems Management
The Federal Aviation Administration (FAA) has asked you to assist in the development of guidelines to standardize “datalink” systems that will allow pilots to receive real-time weather information in the cockpit. This will include information about thunderstorms, icing, turbulence, and prevailing winds. Given what you know about the principles of good display design, what would you consider in designing these guidelines? Some manufacturers would like to display the positions of other nearby aircraft on the display. Others would like to display terrain features and still others would like to display navigation routes and airports. What recommendations would you make on these issues? Why? (9)
•Principle of Need: Give operators what they need to know when they need to know it; if it isn’t needed, don’t clutter the display with it.
•Principle of Legibility: Displays should be clear, distinct, and large enough to be easily legible under all applicable lighting conditions.
•Principle of Display Integration/Proximity: if possible, display should integrate information that the user will need to integrate; related information should be displayed in close proximity.
•Principle of Pictorial Realism: representations should resemble the information they depict.
•Principle of the Moving Part: the part in the display that moves should correspond to the part of the real world that moves
•Principle of Predictive Aiding: when the user of a display must anticipate future states, these should be displayed when the predictions are reasonably accurate.
•Principle of Discriminability: different types of information included in the same display should be easily discriminable.
In general, the idea of combining information into a single display that the user will need to integrate is a good approach. So, the first question is “what information do the pilots need to know?” Only this information should be displayed. The manufacturers are proposing to add a great deal of information to the display. Is all of this information necessary? Can this information all be displayed simultaneously in a manner that is legible and discriminable? If not, can the information be summarized in some way or displayed on request? The information that is displayed should be displayed in a fashion that resembles the real world. For example, terrain should be depicted with colors/shading that elicit the sense of real terrain. Moving objects (e.g., weather, aircraft) in the real world should be depicted as moving in the display and whenever possible both their current positions and predicted future positions should be displayed.
An air traffic controller complains to you that she has to deal with too many “stupid pilots” who repeatedly forget her instructions for where to ground taxi after landing. According to the controller, she always tells the pilots exactly what to do as soon as she sees the airplane’s wheels touch the runway. Why is the controller having this problem? What psychological principles are at work? What would you recommend that she do to help fix the problem? (9)
At touch-down, the pilot’s attention is focused on managing the speed, attitude, and direction of the aircraft as it transitions from an airborne vehicle to a ground vehicle.
The pilots may not have additional attentional or short-term memory capacity.
The controller should wait to provide the taxi instructions until after the aircraft has slowed after touchdown or provide only enough information to clear the aircraft from the runway.