"The Wall Street Journal filed several Freedom of Information Act requests with the Federal Aviation Administration for the entire Enhanced Traffic Management System database, which contains flight records for aircraft that flew in the U.S. under instrument flight rules. The Journal analyzed the flight data for non-commercial jet aircraft traffic for a four-year period, 2007 through 2010. ... The Journal has included in the flights database an estimated cost to operate each flight. The estimates are based on per-hour cost figures for each model of jet, provided by Conklin & de Decker Aviation Information, an industry consulting firm used by some public companies to provide aircraft-cost estimates for regulatory filings."