There are also navigational problems .

此外还有航行问题。

In the event of an engine failure , for instance , it could use its navigational map to locate a suitable area to put down .

比如，如果一台引擎发生故障，无人机需要使用其航行图来找到合适地点降落。

Every helmsman checks his compass-a chinese invention used for the first time in history as a navigational tool on this voyage-and sets a southerly tack as far as the singapore strait then west into the indian ocean .

每一名水手都检查了自己的罗盘（这项中国的发明历史上第一次作为航海工具航行），把指南针设定在新加坡海峡的方向，然后再往西前往印度洋。