The Airplane - Jay Spenser [128]
Transitioning from air traffic control to air traffic management will shift much of the work of aircraft separation to the airplanes themselves within this integrated, information-rich environment. Ground-based controllers will intervene only as needed to resolve arising conflicts if two airplanes are headed for the same airspace. Instead of traffic bunching up along traditional airways and over electronic intersections, flights in this coming environment will be spread out for more efficient use of available airspace.
Already under way, the phased transition to this future air traffic environment will take decades. Major systems integration challenges must be met, enabling technologies must be developed and validated, political considerations such as cost and airspace allocation must be resolved, and a spectrum of other issues and concerns must be properly addressed.
For example, how can the world transition with uncompromised safety from classic air traffic control to the future air traffic management environment when during this interim period some airplanes will be capable of air traffic management and others won’t? And what of the very light jets (formerly termed microjets) now entering service, which raise concerns at a challenging time because they combine business-jet performance capabilities with single-pilot, privately owned and operated general aviation usage patterns?
In recent decades the world has witnessed exponential growth in computer processing speeds and available memory. These astonishing technological capabilities have in turn seen three-dimensional computer applications of all kinds come to market. From action-adventure games to flight simulators to home-design tools, low-cost software has opened up an astonishing variety of virtual worlds to us on our personal computers.
Aviation too drew on these newfound capabilities for yet another safety-enhancing tie-in with the lowly radar altimeter. The idea here was to combine an electronic library of digital terrain data with GPWS for enhanced ground-proximity warning. Together with a third technology, GNS, this new system is little short of revolutionary.
Called TAWS, for terrain awareness and warning system, this mandated safety system combines the radar altimeter’s downward sensing with knowledge of the surrounding terrain as well as the airplane’s position, course, airspeed, vertical speed, accelerations, and configuration (gear and flaps). This gives it the ability to anticipate what’s ahead for more informed and accurate ground-proximity alerts. In mountainous areas, it can also allow the system to guide the crew safely around the highest ground.
Although often described as a forward-looking alerting system, TAWS does not actually sense what is ahead of the airplane. Moreover, its digital terrain data set may fall out of date over time—for example, if a large transmission tower is built atop a hill near an airport. Consequently, provision is made for periodic updating of this digital electronic library.
This virtual world also has the potential to be shown on head-up displays, which are angled glass panels on which projected information, focused to infinity, overlays what a pilot sees ahead. Once found only in military aircraft, head-up displays are today widely used in commercial jetliners. They repeat flight instrument data from the panel and display overlaid symbology offering approach and landing guidance.
Projecting digital terrain data is possible on a head-up display, and it would fill in the missing outside world when flying in bad weather. However, this use of synthetic vision—so called because it is merely a representation of the airplane’s surroundings, not an actual view of those surroundings—has the potentially dangerous drawback of looking persuasive while failing to represent