Originally Posted by boatnfish

I had extra time this week at the Detroit airport. In the C terminal for outbound flights the last C gate is 27. There are doors that go beyond that that are closed off with signs that alarms will go off in you enter. There appear to be valid gates of C-28 and beyond and there were even a couple of regional jets parked at them.

My question is what are these gates for? My guess would be that they are for Delta Connection inbound flights from Canada where you need to go through passport control, but then I don't see where those people reenter the airport for connection flights. Is there another tunnel to the A terminal for passport control? In years past (can't remember seeing them lately) you would see small jets (presumably inbound from Canada) at the A terminal gates that are setup to directly you downstairs for international arrivals.

Any insights would be great.

Thanks in advance