First-quarter revenues at NetJets fell 3.5 percent in the first quarter from a year ago, though profits rose by an undisclosed amount, according to results released on Saturday by parent company Berkshire Hathaway. Berkshire’s service and retailing segment, which also includes FlightSafety International and other-non-aviation businesses, saw revenues climb 35 percent year-over-year, to $4.5 billion.

NetJets’ revenues were affected by “lower fuel cost recoveries and unfavorable foreign currency effects,” Berkshire said. “The decline in NetJets’ fuel surcharge income was substantially offset by lower fuel expense, resulting in a minimal impact on [profits].”

Pre-tax profits during the quarter at the Berkshire segment increased by $97 million, to $384 million, from a year ago. These higher earnings were partially due to an increase in profits from NetJets, thanks to healthier margins on aircraft sales and lower aircraft impairment charges as used aircraft values stabilized, as well as lower depreciation expenses and increased foreign currency transaction gains.