Jon: DSII: Local Air Defense

Jon,
	I have a question for you regarding Local Air Defense systems. 
A LAD with
its minimal range and size of 2 has been refered to as essentially a
stinger missile system.  It can engage aircraft (Areospace and VTOL)
within
its envelope but not missiles.
	However, in the DSII book Air Defense systems are said to only
be able to
engage Areospace and VTOL in high mode.  In StarGrunts a local handheld
missile, which is described as being similar to a Stinger can only
engage
an aircraft in Low mode or hover, high mode being essentially off the
board...
	I understand that engaging an aircraft that is flying low to the
ground
can be harder than engaging one higher in altitude because of line of
sight, terrain blocking, etc.
	However, LAD and other systems should have some ability to
engage aircraft
in low mode, if at a reduced range, effected by terrain.  Otherwise, it
really makes no sense for any infantry units to carry LAD systems, since
they will never be able to hit anything that will really effect them.
	Could you also explain the relation between a stinger type
missile in SG
and what its equivelent in DS would be?
	Thank you,
		Phil