As the number of flights air traffic controllers must handle is steadily increasing (for instance, Shanwick handled 414,570 flights in 2007, an increase of 5% - or 22,000 flights - from 2006), the number of pilots tuned to a particular station also increases.
由于一名空中交通管制员所须处理的航班数量正在稳步增加（例如，香威克在2007年处理了414,570架次航班，比2006年增加了5%——或者说22,000个航班 ），调整到特定频段的飞行员数量也因此增加。