scope:

PURPOSE AND SCOPE

Introduction

This document defines the minimum user performance requirements applicable to in situ Eddy Dissipation Rate (EDR) turbulence computational algorithms (hereafter referred to as "the EDR algorithm"). In situ, as used herein, refers to calculations that use aircraftderived observations, obtained through direct contact with the atmosphere or aircraft, as input (as opposed to remote sensing observations, such as RAdio Detection And Ranging (RADAR) or LIght Detection And Ranging (LIDAR)).

Initially, this Special Committee (SC) set forth to develop a Minimum Operational Performance Standards (MOPS) document to formalize these algorithm performance requirements. However, as the research into defining these performance requirements progressed, it became apparent to the RTCA SC-206 that the issue was much more complex than anticipated. There are several different methods of EDR calculation in the marketplace at this time, and none is preferential over the others; that is, there is no "Gold Standard" method of calculating EDR. Each method has benefits and drawbacks unique to that developer's algorithm. In addition, there are various methods of physically implementing the calculations both on-board aircraft systems or in ground processing systems, each unique to the individual algorithms. This presented the RTCA SC-206 with challenges in utilizing the RTCA MOPS Drafting Guidelines, which are designed primarily for use in defining hardware performance requirements, which can be well established within airframe construct. This is not possible for EDR calculations. In the end, the RTCA SC-206 made the decision to develop a guidelines document instead of a MOPS. The scope of the document is extremely narrow - because of the differences in calculation methods, only the performance of the algorithms in a strictly defined testing environment is considered within scope. This requires developers to adhere to strictly defined testing procedures. Hence, while this is a "Guidelines" document, there are contained within "requirements" for developers to follow when testing their algorithms against the performance requirements provided in this document. These "requirements" set the necessary statistical boundaries for test outputs to ensure operational algorithms will generate operationally comparable reports to be used by a variety of end users.

The requirements of this document apply to developers of EDR algorithms. These requirements specify algorithm output characteristics that should be beneficial to manufacturers, implementers, and other users of the EDR reports, such as flight crews, dispatchers, wake vortex models, meteorological forecasters, and forecast models. Collectively, these output characteristics define a set of requirements that apply to a universal set of EDR algorithms.

Compliance with these requirements is the means of assuring that the EDR algorithm output for a given aircraft will be comparable with that of other aircraft, within a range of accepted uncertainty, for the same turbulence conditions encountered in routine aeronautical operation. Any regulatory application of this document is the sole responsibility of appropriate governmental agencies.