http://www.lvrj.com/news/breaking_news/ ... 80722.html
"Due to higher density altitude, the helicopter 'thinks' it’s higher than it really is, Lorenz said.
'In layman’s terms, if you’re outside and cutting the grass on a normal day you’re going to be fine, but if you’re outside cutting the grass in 110-degree temperatures, you’re not going to perform at your best,' Lorenz said."
That higher density altitude is dangerous stuff.