Detection system for use in an aircraft

A method of detecting an adverse atmospheric condition, including:

• monitoring infrared radiation received from above the horizon;
• generating signals representative of said radiation;
• and
• determining if an adverse atmospheric condition, comprising at least the presence of a cloud including silicate bearing minerals, is present on the basis of said signals.

A detection system, including means for monitoring infrared radiation received from above the horizon, means for generating signals representative of predetermined wavelengths of said radiation, and processing means for determining on the basis of said signals if an adverse atmospheric condition is present and generating a warning signal when said condition is present, characterized in that:

• said processing means is adapted to determine on the basis of said signals if said adverse atmospheric condition, comprising a cloud including volcanic ash cloud constituents, is present,
• wherein said processing means determines said cloud is present if said signals indicate radiation received of a longer wavelength is less than radiation received of a shorter wavelength,
• wherein said predetermined wavelengths fall within the range of approximately 10 to 12 .mu.m, and
• wherein said monitoring means includes an infrared detector array and said signals relate to pixels of said array, such that said signals of each of said wavelengths correspond to each one of said pixels, and said processing means generates display signals representative of the position of said adverse atmospheric condition relative to said system on the basis of said signals and position signals representative of the position of said system.