BIK. .. .What's this mean? </font><blockquote><font size="1" face="Verdana, Arial, Helvetica">quote:</font><hr /><font size="2" face="Verdana, Arial, Helvetica"> Or it may have the power to get it there, but not the LIFT to keep it there. </font><hr /></blockquote><font size="2" face="Verdana, Arial, Helvetica">Actually
Shon I need to correct myself. The power of a jet engine falls with altitude so that a point can be reached where the engine is working too hard in order to maintain sufficient thrust to climb any more. Unlike Concorde, 747 engines are kept within limits to extend time between overhauls. Going higher would become un-cost effective.