Avinor has also proposed lowering the terrain east of the airport. The terrain is actually flatter to the east, but because the runway was expanded in that direction, the extension cannot be used without removing all ground in the twelve-degree slope. Although it has no impact on smaller aircraft, the reduced runway length has a severe impact on the performance of Boeing 737 aircraft, which are used by both Norwegian and SAS. For instance, during winter a 180-seat 737-800 can only utilize 71 percent of its permitted take-off weight; this would hinder fully loaded aircraft flying further than Oslo. The impacts for 150-seat 737-700 aircraft are smaller, as they can reach Oslo during winter and Berlin during summer. The airport served 169,428 passengers in 1996 and 216,000 passengers in 2000.