独立主格结构为分词作状语。如果用had been cancelled, 就成了谓语动词了，要么用并列句，要么用主从复合句：

All the flights having been canceled because of the snowstorm,  we had to take the train instead. 独立主格结构作原因状语

Because all the flights had been canceled because of the snowstorm,  we had to take the train instead. 原因状语从句

All the flights had been canceled because of the snowstorm,  so we had to take the train instead.  so连接并列句