AC120-42A是什么？

120V42A的交流电

Technical - AC120-42A: "For the purpose of this AC, extended range operations are those flights conducted over a route that contain a point further than one hour flying time at the approved one-engine inoperative cruise speed (under standard conditions in still air) from an adequate airport."

这是什么意思啊？
我英文不好
技术- AC120-42A ： “为这AC的目的，扩充的操作是包含点更加进一步比一小时飞行时间以批准的一引擎无效果的巡航速度的那些飞行被举办在路线(在标准条件下在寂静的空气)从一个充分机场”。

上面是机器翻译的，希望你能明白