The aviation industry over the past twenty years has experienced rapid growth and also considerable fluctuations about this growing trend. It is fluctuations about this trend, even though they may be of relatively short duration, which make or break airlines. In Table I(a) for instance, are shown the fluctuations about the trend of fares, load factor, international airline operating projects, aircraft investment and output. The institutional structure within which air travel operates is shown by the small variation in fares, while aircraft investment and profits show wide fluctuation. Reference to the last three columns shows the synchronised cycle in aircraft producer profits. We shall enquire into some possible courses of these fluctuations, and then examine the consequences of these fluctuations on used aircraft prices and financial performance of the airlines.