Medium aircraft are those that weight between 15,500 pounds and 300,000 pounds while  havy aircraft are those weighing 300,000 pounds or moreOn this level, these designators are  simply one way of classifying aircraft by size.

中型飞机是指重量在 15,500 磅到 300,000 磅之间的飞机，而重型飞机是指重量在 300,000 磅或以上的飞机。在这个级别上，这些代号只是按尺寸对飞机进行分类的一种方式。