454 Data indicate that the probability that a given midstream facility will be detected appears low, is somewhat dependent on the size of compression and processing emissions, 456 and is unpredictable between overights. resulted in a plume at a particular location. There are two implicit assumptions in this scaling method: (a) that the probability of detecting a plume is representative of all time, i.e. 24 hours per day, 7 days per week, and (b) that detections are equally probable for the same source on all overights. Data from this study indicates that both assumptions are not wholly correct, and that scaling from aerial detections to basin emissions requires more analysis and conditioning than is currently applied.