Time-evolving distribution of time lags between commercial airline disasters

We have studied the time lags between commercial line airplane disasters and their occurrence frequency till 2002, as obtained from a freely available website. We show that the time lags seem to be well described by Poisson random events, where the average events rate is itself a function of time, i.e., time-dependent Poisson events. This is likely due to the unsteady growth of the industry. The time lag distribution is compared with a truncated Tsallis distribution, thereby showing that the "phenomenon" has similarities with a Brownian particle with time-dependent mass. We distinguish between "other causes" (or natural causes) and "terrorism acts", the latter amounts to about 5%, but we find no drastic difference nor impact due to the latter on the overall distribution. (c) 2005 Elsevier B.V. All rights reserved.