The airplane's maximum altitude is 18,000 feet.

飞机的最大飞行高度是18000英尺。

The method of triangulation was one of the means I used to determine the rockets' maximum altitude.

方法是三角的手段之一，我用，以确定火箭队的最高海拔高度。

When the cloud's maximum altitude was less than 5km (3 miles), ATDnet detected no lightning from it.

当云最大海拔高度不超过5千米也就是3英里时，用ATDnet监测不到云层里的任何闪电。