Colonial marines testing tools

I am big fan of Alien movies. When I first saw Aliens (second one), it was just pure entertainment for me. But, when I think again about Aliens, now as a software tester, I noticed that colonial marines were using some cool combat gadgets. Meet the "Motion Tracker".
From this video, it is clear that colonial marines put their trust (and lives) a lot in hands of motion tracker.
But should they have done that? Ending scene gives us significant flaw of motion tracker. It can only detect motion, but in one dimension. Aliens were coming from  direction expected by colonial marines, but form the floor above the colonial marines!
As a software tester you must not put all your trust in testing tools. Use them wisely, question their features and adopt them to your problem domain. Testing tools could be a great assistance to software tester, but testing tools are meant to be used by software testers, not vice versa.