Simulation of infrared detection range at fog conditions for Enhanced Vision Systems in civil aviation

Abstract

The DLR project ADVISE (ADvanced VIs-ual System for Situation Awareness En-hancement) deals with development, simula-tions and testing for an Enhanced Vision Sys-tem (EVS) for visual pilot assistance. Within the frame of the project ADVISE, model cal-culations in the infrared spectral region have been performed to investigate the influence of low visibility conditions, especially fog, for air traffic during landing approaches. The objectives of this paper are to find out whether the use of IR cameras for an EVS can improve the visibility at defined conditions of ICAO standard visual range categories CAT I, II, III a and III c for landing approaches. The calculations are carried out with the atmos-pheric radiative transfer model MODTRAN Version 4.0. The IR detection range is calcu-lated in the atmospheric windows 3-5 ìm and 8-12 ìm and compared to the visual range defined at 0.55 ìm. The sensor properties are simulated with the model TTIM (TACOM Thermal Image Model) for a specific IR cam-era type Thermovision 570 operating in the spectral band 8-12 ìm. The influence of vari-ous climatic and seasonal meteorological conditions, aerosol types and target parame-ters, such as temperature and size, on the IR detection range is taken into account.