[avi8torny]

Originally Posted by xlr8

Sikorsky S-70 - Wikipedia, the free encyclopedia
History : Weather Underground
Density Altitude Calculator
http://www.faa.gov/library/manuals/aircraft/media/faa-h-8083-21.pdf

Wiki reports hover out of ground effect-4300'. In ground effect-9000'
Wx at South Lake Tahoe shows wind speed and direction varied throughout the day.
Density altitude as much as 8316'.
There is a brief description of Loss of Tail rotor Effectiveness at altitude in the FAA Rotorcraft Handbook chapter 11, page 13.

Hover IGE for a -60 has got to be more than 9000'.