精确、低成本和全球可获得性使得GPS已成为仪表飞行规则(IFR)“自由飞行”的关键,现在看来这是不可避免的。GPS可使每架飞机连续地确定自身位置,当在云层中飞行时,可避免与其它飞机相撞。自由飞行的概念是,它从空管系统中消除了程序间隔。随着自由飞行的实施,所有驾驶员都可选择自己的航路和高度,就象我们在目视飞行规则(VFR)下所作的那样,只是自由飞行将适用于所有的能见度等级。IFR是通过使用规定的航路、高度和管制员的矢量,而从程序上区别交通 Accuracy, low cost and global availability make GPS the key to IFR “free flight ” and now it seems inevitable. GPS allows each aircraft to continually determine its own position, avoiding collisions with other aircraft as it flies in the clouds. The concept of free flight is that it eliminates procedural separation from ATC systems. With the free flight, all pilots can choose their route and altitude, as we did under the VFR, except that free flight will apply to all visibility levels. The IFR distinguishes traffic by using prescribed routes, altitudes and controller vectors