Some time ago an ex colleague of mine ferried an ATR42 on a delivery flight from Canada to Europe at level 290!!
This because "you don't have pax on board, you will just get the cabin altitude warning but you can silence it and accept a higher cabin altitude, you will catch up strong tailwinds, and burn much less at that level"...
For those who don't know, the max altitude on the ATR is 25000ft, if I remember correctly.
In the hope one day this guy will read these lines, I encourage you to post as much as possible.
Thanks
