http://news.yahoo.com/s/ap/plane_crash_investigation

I think this was reported a month ago as well, but there was another
round of news releases today stating that the pilots took their
Bombardier CJR200 to its maximum altitude of 41,000 ft. Afterwards,
both engines failed and they crashed before reaching an airport.

Of course, the pilots should not have experimented around, but is it
dangerous to take a plane to its max altitude? When the engineers
specify a maximum altitude, doesn't it still have to be safe at that
altitude?