provide sensors, models, data display, local weather information, and information about the paths of preceding aircraft.

Advances to spacing systems and vortex alleviation will both require specialized research and technical advances in vortex modeling, vortex measurement, meteorological measurement, and vortex visualization. Supporting studies such as hazard boundary definition, system-level benefit studies, and the development of a system to gather data about wake events will be key to targeting research and eventually implementing solutions. Not only do they require the same supporting research, but alleviation and spacing also are not mutually exclusive—the best possible system may include elements of each. This section presents these technical challenges in more detail, along with relevant findings and recommendations.

First, however, a caveat: Because this report focuses on the wake vortex research needed for enabling capacity increases, approach and landing issues and, to a lesser extent, takeoff wake vortex issues were the main considerations. However, en route spacing reductions may also prove necessary to accommodate increased demand. The spectrum of aircraft to be commonly used in high-altitude jet flight will grow as the A380, at 1.25 million pounds maximum takeoff weight, is introduced at the high end, and “very light jets,” at perhaps as low as 6,000 pounds takeoff weight, are introduced at the low end. New safety challenges may also arise with the 1,000-ft minimum vertical spacing procedures recently adopted in many parts of the world for IFR operations. The FAA’s Web site contains more details: <www.faa.gov/about/office_org/headquarters_offices/ato/service_units/enroute/rvsm/>. The JPDO should not ignore these issues. Fortunately, most of the research challenges presented here may also be applicable to en route spacing.


Finding 3-1. En route wake vortex issues may arise, especially for very light jets in cruise.


Recommendation 3-1. The JPDO should investigate and define specific requirements for research on the impact of cruise-altitude-generated wakes on capacity (including climb and descent) to avoid future problems as fleet diversity increases.

IMPROVED SPACING SYSTEM DESIGN

Wake vortex considerations affect aircraft spacing standards for en route, approach and landing, arrival and departure. The FAA Research, Engineering and Development Advisory Committee’s (REDAC’s) Separation Standards Working Group (SSWG) found that “the current system,



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