Engineers Air Control Gets "F" for Letting One Of Their Missing Ships Come Back With "0" Concerns

We do not know anything about the Planet 4 inhabitants' technological capabilty. It is possible that they hadn't seen other/higher level Engineers for 2000 years. Their knowledge turned into religion? Would you fire Jesus' spaceship if it appeared over New York?

@op good questions, and good comments

@ati once again, I like that idea too. This film is too deep to just disregard a possibility for no reason. There are WAY too many options (in a good way) to "control" what we think should have/should be happening in this film.

because it was convenient to the story, that's the biggest reason.

NO I don't like that reasoning either, but that's how it is.

Everyone assumes the Engineers are going to behave like us, that they warred amongst themselves and had a tech fall, that religion replaced reason.

This might have been a Preserver colonu. One set up expressly by those who made the choice to live by ancient standards, to preserve the 'essence' of their civilization.

Such a colony would have no air traffic control and no fears of a military vessel. They would be there to see it, as it's likely such visits would be rare and a hallmark event.

Perhaps he used a special Engy-code, contacted them in Engy-speak or something else which meant he could fool or bypass their security protocols?

In any event they were expecting the Juggernaut and had no suspicions or concerns about it's arrival. 

Think of it this way:

Say you take a decently-large town from way up north. A C-130 comes in and everyone's expecting supplies and such.

Then it drops a few daisycutters or thermobaric cluster munitions.

Same idea.

The colony idea makes sense. But this is assuming they chose to be vulnerable because their religious believes may have lead them to think whatever happens on that planet was in the hands of what they believed in. 

But why did Shaw and David fly to this colony planet in the first place when we are lead to believe that the ship was heading to the Engineer's home planet at the end of Prometheus? Did they miscalculate the destination of the ship? Was there a "Return to Base" button that malfunctioned? Or was the ship programmed to make a short stop (even kill this religious group of engineers) at this planet before heading back to the real home base? 

Did the engineer's real home base even get a signal that one of their missing ships was en route to another planet? Since they have such advanced technologies, there must be a way for engineers Air Force to monitor their fleet across galaxies? If so, why didn't Engineers real home base send an expedition to find and search to this recent transmission?

Are different sects of Engineers (religious or not) completely segregated (no communication at all)? Even if they live on different planets? There is no central relations between them? 

MoXeno~ those are questions we all want answered!

Lone, that's the beauty of Alien franchise.