Going back to WIWALOnSy/ww/wx/pu/sc/gaz,one would do a power-check at min.power speed/max climb power speed,in level flight near the area that you intended to land,hover,winch either offloading or picking-up,and check max power available(to first engine limit/tq,n1,tgt,m-p,and then decide what you could actually do.Admittedly,a lot were `rule of thumb` calculations,adjusted by `experience`,or lack of info. in the PNs/crew manual.So what do you chaps do now ,with all the FADEC systems ,etc.>???