HML            Helicopter, Marine, Light
HMM           Helicopter, Marine, Medium
HMH           Helicopter, Marine, Heavy

The Navy uses the same nomenclature but just leaves the M (Marine) out.  HC-3 is Helicopter, Cargo.  Fixed wing is V, etc.

Taxi-ing out. The Marble Mountains in the background. Honeycombed with tunnels, it is thought the North Vietnamese built a hospital in them.  At night, you could see the tracer.  Green for 'gooks', red for the good guys.  There never was any attempt to clear them out, even though they were less than a mile from the end of the runway. As the guys used to say "It's a f**ked up war."

There was never any attempt to clear the mountains. Copyright John Dullighan 2000