A DOT Inspector General report on National Airspace System usage does not support AOPA’s and NBAA’s arguments that general aviation operators are only marginal airspace users. It did, however, support the groups’ claims that GA operators typically avoid using airline hub airports. Using 2005 flight activity data, the DOT IG found that both GA operators and airlines contribute to congestion at terminal area radar and en route facilities. The watchdog agency said GA operators are the major users of FAA tower and terminal area control services at 59 percent and 49 percent, respectively, though business jets accounted for only 12 percent and 13 percent of these services, respectively. Airlines were found to be major users of FAA en route services, accounting for 79 percent of the total. The DOT IG also found that “a tax based on jet fuel consumption is a better proxy for the use of the NAS than the current aviation excise taxes, but it does not measure whether air traffic control services are used.” NBAA is still reviewing the report and plans to meet with the DOT IG in the coming weeks to discuss the study.