Airborne measurements have been made in the smokes from large fires of standing coniferous trees and logging debris, standing chaparral, fallen jack pine, and wheat stubble. Panicle emission factors, particle size distributions, optical properties of the smokes, and trace gas concentrations in the emissions are derived from the airborne measurements. Major differences exist in these factors during anyone fire, as well as from one fire to another. Measurements of optical scattering and extinction coefficients, with a time resolution of a few seconds, reveal significant spatial inhomogeneities in optical absorption within the smoke plumes.