AbstractAn airfreight container equipped with automated analyzers and collectors for atmospheric trace compounds has been operated on a monthly basis onboard a Boeing 767-300 ER of LTU International Airways during long-distance flights from 1997 to 2002. Based on the success of this system a new, more advanced CARIBIC system has been developed and implemented. Based on a larger capacity container with more equipment, in combination with an improved inlet system which includes a remote sensing DOAS system, CARIBIC phase #2 was implemented on a new long-range aircraft type Airbus A340-600 of the Lufthansa German Airlines (Star Alliance) in December 2004. By this a powerful flying observatory has been realized. The instrument package comprises detectors for fast and standard O3 measurements, measurements of total and gaseous water, NO and NOy, CO, CO2, O2, Hg, and particle number concentrations of sub-micrometer particles (>4nm, >12nm, and >18nm). Furthermore, an optical particle counter and a proton transfer mass spectrometer (PTR-MS) are installed. Aerosol samples are collected for elemental analysis, and particle morphology in Lund. Air samples are taken in glass containers for careful laboratory analyses of hydrocarbons, halocarbons and greenhouse gases in several laboratories. Absorption tubes collect oxygenated volatile organic compounds. Three differential optical absorption spectrometers (DOAS) with their telescopes mounted in the inlet system measure atmospheric trace gases such as e.g. BrO, NO2. A video camera mounted in the inlet system provides information about clouds, lightning events. The system description and examples of measurements are reported.