Math problem

从地图看，苏联赤塔距离中蒙边境414号界桩的直线距离是800公里，而赤塔距温都尔汗的直线距离约600公里。林彪专机每小时飞500多公里，怎么可能半个小时飞1400公里？

赤塔 is on the north of board between Mongolia and Russia.  温都尔汗 is inside the Mongolia.  The flight distance from the China-Mongolia board to 温都尔汗 should not be the adding result 1400 km but more likely the result of subtraction 800-600 = 200 km.  Then half hour flight distance is more or less correct.