Air traffic systems have long relied on automated short-term conflict prediction algorithms to warn controllers of impending conflicts (losses of separation). The complexity of terminal airspace has proven difficult for such systems, as it often leads to excessive false alerts. Thus, the legacy system, called Conflict Alert, which currently provides shortterm alerts in both en route and terminal airspace, is often inhibited or desensitized in areas where frequent false alerts occur, even though the alerts are provided only when an aircraft is in dangerous proximity of other aircraft. This research investigates how a minimal level of flight-intent information may be used to improve short-term conflict detection in terminal airspace such that it can be used by the controller to maintain legal aircraft separation. The flight-intent information includes a site-specific nominal arrival route and inferred altitude clearances in addition to the flight plan that includes the area-navigation departure route. A new tactical conflict detection algorithm is proposed, which uses a single analytic trajectory, determined from the flight intent and the current state information of the aircraft, and includes a complex set of current, dynamic separation standards for terminal airspace. The new algorithm is compared with an algorithm that models a known en route algorithm and another algorithm that models Conflict Alert. This is done by analysis of false-alert rate and alert lead time with the use of recent real-world data of arrival and departure operations and a large set of operational error cases from the Dallas/ Fort Worth terminal radar approach control. The new algorithm yielded a false-alert rate of two per hour and an average alert lead time of 38 s.

No abstract

No abstract

SummaryA new concept for air traffic management in the terminal area, implemented as the Center-TRACON Automation System, has been under development at NASA Ames in a cooperative program with the FAA since 1991. The development has been strongly influenced by concurrent simulation and field site evaluations. The role of simulation and field activities in the development process will be discussed. Results of recent simulation and field tests will be presented.

This paper is concerned with the estimation of parameters in a constant coefficient, linear system using measurements of the system input and output. Two general methods can be used to estimate these parameters: the equation error method and the output error method. The equation error method is characterized by a single step solution that does not require a prior estimate. Unbiased noise in the output, however, causes a bias in the estimated parameters. The output error method is characterized by iterative solution techniques that require a prior estimate of the unknown parameters. This method provides an unbiased estimate. In this paper, a single estimation procedure is presented that uses the best features of both methods. It does not require a prior estimate of the unknown parameters and unbiased noise in the output will not cause a bias in the final estimate. The method is applied to simulated and flight data.