As a federal statistical agency, BTS releases data based on a published schedule. BTS issues monthly press releases on the Freight Transportation Services Index, airline traffic, scheduled passenger airline employment and North American surface freight. Quarterly releases are issued on average domestic air fares and airline financials, including baggage fees and reservation change fees. BTS is the source of available statistics on airline on-time data and tarmac data. BTS’ tarmac data was widely used in deliberations on the issue of lengthy tarmac times, which has been well-publicized in the last three years. BTS’ data is the key indicator of the effectiveness of the federal rule implementing a three-hour time limit on planes sitting on the tarmac. The rule went into effect April 29, 2010.