The door gunner on my right has his M60 machine gun up and ready to use. You never know what will happen when landing in the jungle. Ammunition for the M60 was feed from the metal box you can see just below the gun. See that red ring on the front of the box? That is the top of a smoke grenade. We used smoke grenades in colors like red, yellow, blue and green to mark landing areas in the jungle.
In the snapshot below you can see an officer and a sergeant having a discussion on the jungle floor. They were on the first-in helicopter. They are deciding how to set up the perimeter. We always set up a perimeter around the landing zone to protect the helicopters that were still landing. That is my knee in the lower right corner of the picture.
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If the whole company was landing, there would be about three waves of five helicopters coming in one after another. I can't imagine what the enemy thought if they were within a kilometer of a landing site. All that noise disrupting their quiet space. If I was them I would have have been tempted to run in another direction.