This paper gives an overview of Base of Aircraft Data (BADA), an Aircraft Performance Model developed and maintained by EUROCONTROL. BADA is based on a kinetic approach to aircraft performance modelling, which models aircraft forces. The intended use of BADA is trajectory simulation and prediction in Air Traffic Management (ATM) Research and Development and strategic planning in ground ATM operations. BADA is used for various ATM-related studies which require information on aircraft performances. The paper provides details on the existing BADA family 3 model and the latest achievements in the development of the new BADA family 4 model. Several examples of the applications of using BADA are provided, together with information on how to obtain access to BADA.

This paper provides an analysis of the BADA aircraft performance model capabilities and addresses the BADA model ability to provide accurate modeling of aircraft performances over the complete flight envelope for a number of aircraft types and different ways in which an aircraft can be operated during the flight. The focus of the paper is the support of complex aircraft operations by BADA. A short description of the two existing BADA families and their main characteristics is given. The complex flight instructions and operating regimes -economy climb, cruise and descent based on cost index, maximum range cruise, long range cruise, optimum altitude and maximum endurance cruise -identified as key features in support to optimized flight execution are discussed. The optimization procedures and equations in which they derive are presented and the ability of the BADA model to support these flight operations is demonstrated. It is shown that BADA 4 can be successfully used with complex instructions and operating regimes, whereas the use of BADA 3 is limited. Finally, the results of a validation experiment dedicated to BADA thrust models are presented.

This paper proposes two scheduling approaches, onelevel and two-level scheduling, for synchronous periodic real-time task sets based on the Imprecise Computation Model. The imperative of real-time systems is a reaction on an event within a limited amount of time. Sometimes the available time and resources are not enough for the computations to complete within the deadlines, but still enough to produce approximate results. The Imprecise Computation Model is motivated by this idea, which gives the flexibility to trade off precision for timeliness. In this model a task is logically decomposed into a mandatory and optional subtask. Only the mandatory subtask is required to complete by its deadline, while the optional subtask may be left unfinished. Usually, different scheduling policies are used for the scheduling of mandatory and optional subtasks. For both proposed approaches the earliest deadline first and rate monotonic scheduling algorithms are used for the scheduling of mandatory subtasks, whereas the optional subtasks are scheduled in a way that the total weighted error is minimized. The basic idea of one-level scheduling is to extend the mandatory execution times, while in two-level scheduling the mandatory and optional subtasks are separately scheduled. The single preemptive processor model is assumed.

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