When you are home ,give a call to let me know you have arrived safely

问题描述:

When you are home ,give a call to let me know you have arrived safely
为什么不说will have arrived?when的从句是主将从现可是后面半句表达的是将来的意思

但是整句话的意思是,当你到家后,给我个电话让我知道你'已经’到家了.
后半句强调的是完成时态.而且有将来完成时这个说法么.