Modeling Time and Space Metering of Flights in the National Airspace System

Metering flights at key points such as sector crossings is an important operational procedure in mitigating National Airspace System (NAS) traffic congestion due to high demand or changing weather conditions. The authors combine a mathematical model for minutes-in-trail or miles-in-trail (MIT) metering with discrete event simulation in a newly developed tool that can be used by analysts to examine or predict existing or developing bottlenecks within the NAS. We define a penalty function recursively in terms of MIT delays between leading and following flights. Such a recursive MIT penalty function has been implemented in a NAS-wide discrete event simulation at CAASD to provide predictive assessment of MIT-related delays locally and globally. It is possible to examine the anticipated MIT delays for all the flights scheduled to arrive at any crossing point. Impacts of flight cancellations, route changes, and additional en route delays as results of airport or sector congestion can all be evaluated during each simulation by updating the scheduled flight crossing times and the expected MIT delay penalties for all the trailing flights. A limited test case quantifying the impacts of increasing spatial arrival separation at a busy airport is provided to illustrate tradeoffs between en route queuing delay versus airport arrival queuing delay both locally and globally.