Encoding of Graphical Images for Aviation Use

The impact of weather on aviation safety is well documented and the impacts as well as the opportunities for improving this hazardous situation are great. Promising new technology and applications are emerging that provide the pilot with near-real-time weather information in the cockpit. The aviation industry and the Federal Aviation Administration (FAA) are in the process of developing standards for both the technology and the applications. The goal is to develop interoperable avionics and services that are affordable while fostering business opportunities for the industry. A large step toward achieving this goal is to standardize the basic weather product formats and display guidelines and allow the avionics manufacturers to customize their hardware implementation and value-added services. Basic weather products should include of common textual information (e.g., METARs, PIREPs, AIRMETS, SIGMETS, etc.) in addition to graphical weather information, such as a precipitation reflectivity image.

This paper describes an approach for encoding graphical weather images for distribution to aircraft that will be demonstrated in the FAA's Alaska Capstone and Safe Flight 21 Projects. The approach focuses on providing a globally consistent registration of product data in a manner consistent with presentation on a moving map display. Minimizing the impact on communication bandwidth and enabling robust product delivery are also considered important factors in this approach. The result is a simple format that utilizes a standard Run Length Encoding (RLE) algorithm with coding enhancements to provide compact, loss-less data messages. This approach has the operational benefits of providing seamless product presentation from multiple communication sources, supporting variable size products or geographic coverage requirements, and enabling the display of a portion of the total image as it is received in the aircraft.