Perspective Guidance Displays Show the Way Ahead

Abstract

LITTLE over two decades ago, programmable electronic flight instrument display systems (EFIS) were introduced in commercial aviation aircraft such as the Boeing B757/767. The introduction comprised three new instruments: the primary flight display (PFD), replacing the traditional attitude director indicator (ADI); the navigation display (ND), replacing the horizontal situation indicator (HSI); and the engine indicating and crew alerting system (EICAS), replacing the engine gauges and a whole slew of other indicators and controls. This introduction changed the face of the cockpit flight instrument panels in civil aviation, earning its nickname of “glass cockpit”. However, more than the mere looks of the flight deck changed. The flight management system (FMS) got a central role in the flight practice, and piloting changed, from interaction with the aircraft supported by some automation to interaction mainly with the automated systems. The introduction of the glass cockpit and the new way of flying civil transport aircraft through automation was reluctantly accepted by the pilot community. Besides early complaints about the readability of EFIS displays, the main issues were the problems of keeping the pilot in the loop, and explaining what the automation is doing at any time, supporting the flight crew “mode awareness”. Still, as accident statistics now show, safety has increased and nowadays flight decks with EFIS and FMS are the norm for commercial and business aviation, and are introduced even in general aviation. With the introduction of the glass cockpit came an increased level of navigational situation awareness, in particular through the added functionality of the navigation display. Its forebear, the HSI, showed an abstract presentation of relative bearings to selected beacons and the distance expressed in dots to VOR radials or the localizer. The ND replaced this by a much more intuitive display of relative geographical position with respect to waypoints on the planned route, approach fixes, markers, and the runway centerline. A planned approach was now visible on the display rather than just on an approach plate. As altitude and speed constraints could be assigned to waypoints in an approach procedure, the energy management during an approach, which depended so far on rough mental computations, was significantly improved as well. Although the electronic instruments offer much more functionality and integrated information than their electromechanical counterparts, they still are not more than two-dimensional “orthogonal” presentations of attitude and geographical position which the pilot must mentally integrate. There must be a world of possibilities in the electronic instrumentation that we have only begun to explore. Unlike autonomous robotic vehicles, humans are capable of interpreting and moving through dynamic three-dimensional environments with little or no conscious mental effort. This talent to intuitively do things right, to not become disoriented or collide with obstacles while moving through the most complex of environments, is a product from ages of evolution. Besides mental reasoning, judgment and a talent for producing solutions when confronted with unforeseen situation (in other words, improvisation) this represents one of the important assets of the human pilot. However, it was up to now not exploited to its fullest potential because of the “unnatural” way of presenting the information to the pilot. Therefore, the current practice to have different abstract, two-dimensional presentations of the aircraft guidance and navigation situation needs to be revised. A future primary flight display should present the aircraft’s spatio-temporal situation, i.e. its motion in space and time, in a way that is intuitively understandable, that supports pilots in their manual and supervisory control tasks, enhances their situation awareness even more, and is compatible with the various tasks imposed by the air traffic management system, now and in the future. Advances in this field have been made with perspective flight-path displays such as the “tunnel-in-thesky,” the “pathway-in-the-sky,” or the “highway-in-the-sky”. These displays integrate the guidance information with