Revenues at Berkshire Hathaway’s services group–which includes fractional provider NetJets and flight-training provider FlightSafety International–were $8.435 billion last year, an increase of $643 million over 2007. While FlightSafety helped contribute to increased earnings in the division, lower earnings at NetJets offset those increases. In the fourth quarter, NetJets “experienced a significant reduction in revenue as general economic conditions worsened,” Berkshire said. “This resulted in lower customer usage and demand, which negatively affected operating margins. In addition, NetJets incurred charges of $54 million to write down the aircraft fleet.”