A newly developed instrument was deployed on the NASA DC-8 airborne laboratory during the Subsonic Aircraft: Contrail and Cloud Effects Special Study (SUCCESS, Spring 1996) to detect and collect heterogeneous ice nucleating particles (IN) in the upper troposphere and lower stratosphere. The elemental compositions of both ambient particles and IN were determined with single particle analysis using analytical electron microscopy. IN collected during flights on May 4 and 8 had enhanced number fractions of metallic, crustal, and carbonaceous particles, compared with the ambient aerosol population, and were relatively deficient in sulfur-containing particles. IN sampled within aircraft exhaust and contrails had higher number fractions of metallic particles, which includes those rich in Zn, Al, and Ti, than the IN sampled in air that was not immediately affected by aircraft exhaust. ¿ 1998 American Geophysical Union