Planes still depend on elaborate groundbased radar systems, plus thousands of people who watch blips on screens and issue verbal instructions for takeoffs, landings and course changes.

• 飞机起降依然有赖精密的地面雷达系统，以及数千名人员监控雷达屏幕上的光点，随时提供起飞、降落及航线变更的口头指示。