A helicopter can maintain a higher altitude in "clean" air. When it hovers,
it pushes the air down and to maintain altitude it has to "climb" through
this decending air. This effect is strongest out of ground effect. What
this means is that, if the IGE ceililng is 12,000 and the OGE is 8,000" the
helicopter could hover over 11,980' terrain at 12,000' but could only hover
at 8,000' over 7900' terrain.

Mike
MU-2
wrote in message
oups.com...
When reading performance specs for helicopters I see the terms IGE and
OGE. I understand they are in ground effect and out of ground effect,
but when the altitudes are given they don't make sense to me. I thought
ground effect was up to one-half the rotor span and anything above that
would be out of ground effect. So what is the difference between hover
ceiling IGE and OGE?