Truth or lie
 

Hello, I have a doubt, assures me a friend that the suggestion of engine power that comes in ALL plans for construction
it is made with respect to sea level basically, and then other parameters are used. I think maybe on some planes, but that's usually done taking into account, NACA, weight of the plane, wing position, wingspan, etc. and not the sea level reference, I have flown many years both at sea level and as many at 6000 feet and I know what height affects airplanes..
What do you think about ?

My thought is that the designer creates the plane for his/her use at whatever altitude above sea level the designer lives. Adjustments might be needed if you are higher or lower than that reference point.