A helicopter pilot failed to check NOTAMs on the night of his flight and while using night vision goggles could not see a large tower along his route of flight which had been NOTAM'ed as unlit.

Narrative

I departed from Tullahoma airport under night vision goggles (NVG). Having performed numerous flights in this direction in years past; I am well familiar with a 1;750 FT tower located inbetween Tullahoma and Manchester. Since we frequently go to Manchester as well; I often look for the tower immediately; and navigate well south of it. On this particular night; I immediately saw what I believed to be the tower and set my course well clear of it to the south. But as I continued my climb; I began to feel like something was not quite right with the tower I was looking at. It looked as if the upper red light was possibly out on the tower. Then I began to wonder if the tower was in fact the right tower at all. Since Manchester is in the immediate background behind the tower; I lifted my goggles to try and distinguish the red lights with my naked eye; (if possibly I was just not seeing the tower and looking at the wrong one) but was unable. After several attempts of raising and lowering my goggles; I still did not see the tower until about the third time when I lowered the goggles I did see the large tower looming in the darkness passing well below us and off to our side... TOTALLY UNLIT. The tower I had been looking at and avoiding was a smaller tower off to the north of this larger tower. The tower was my highest obstacle on my direct line of flight; I was totally looking for it from the moment I departed Tullahoma to circumnavigate it; and I had every intention of traversing around it by a safe distance. And yet; I came closer to the tower then I would have liked; and it was rather uncomfortable to see it suddenly looming in the darkness passing below me off to the side; even though I was not about to hit it. It was just something rather large and ominous that didn't belong up there in the night sky with me. I immediately notified Flight Communications of the unlit tower; I radioed the check airman who was in the pattern doing training of its presence; I informed the oncoming pilot of the hazard the next morning; and he was kind enough to update it on the hazard map for me (I flew all night). This particular incident gave me a real respect for the NVG goggles; and made me question how many towers are looming in the darkness out there that we never even know about on a long cross country; especially into unfamiliar terrain. I think most of us take it for granted that large towers especially are always lit; but that is obviously not true. It also made me aware of my lack of situational awareness in having confused a smaller tower to the north with this larger tower that was unlit. My experience has also reinforced for me the validity of the highest obstacle awareness along our route; the need to acquire the safe obstacle clearance altitude and maintain it (if in doubt of circumnavigating); and the vigilance of maintaining the hazard map.