Have we been witness to the Helicarrier without knowing it?

When I first watched The Avengers trailer I was wondering about two small snippets of footage. There is a few seconds of footage (0.30-0.34) of a helicopter landing in, what looks like, a military base. Nick Fury exits this particular helicopter. It made me wonder if he was just joining the military at a base ready for the impending 'war'? Then I considered that it could be the Trikelion making an appearance? I then thought that what if it was the Helicarrier? I had scoured the stills of those particular scenes to see if the paticular facility was in the air or not but all I could see was water! Articles claiming knowledge of the Helicarrier posted prior had said that it would be hoveing invisibly above the city. I thought it was best to leave my wasteful theorising there.

But an article was posted by DCMARVELFRESHMAN yesterday that claimed to have knowledge of particluar scenes that will appear in the movie. One bit stuck out for me. this is a SPOILER WARNING:

"SPOILER ALERT!! The Helicarrier starts out on the water like a regular aircraft carrier and then the outside fins begin to rotate and then the anti-gravity/turbines fire up and then it slowly rises out the water and begins flying away"

When I saw that (if the scene description proves to be true) the Helicarrier is actually based in the water when not in the air then the Helicarrier could well have been shown to us in The Avengers first official trailer without anybody taking time to notice. It's a theory at best but one that I thought was worth sharing.