Going South?

The recent increase in flight delays in the U.S. domestic system is analyzed by estimating an econometric model of average daily delay that incorporates the effects of arrival queuing, convective weather, terminal weather conditions, seasonal effects, and secular effects (trends in delays not accounted for by other variables). From the estimation results it was possible to quantify some sources of higher delays in late 2003 and early 2004 and track changes in delays that are not attributable to major causal factors. Results suggest that when these factors are controlled for, delays decreased steadily from 2000 through early 2003, but that the trend reversed thereafter. Of the total delay increase between early 2003 and early 2004, half to two-thirds can be attributed to specific sources.