Folks,
It seems to me that there have been a lot of posts mixing up a number of concepts.
The Certification rules determine
minimum installed power in an obstacle free environment - it is done by requiring minimum gradients in various configurations.
The Operating rules determine
maximum allowable mass in a real world environment - it is done by requiring obstacle clearance in various configurations.
Instrument Procedure designs determine
obstacle clear planes regardless of various configurations.
How does it all come together for me as a pilot: fairly simply really, because I have to obey the operating rules and that satisfies the others. The mass at which I operate must take into account the limiting obstacle clearance requirements, regardless of the particular procedure and considering contingencies, the most common of which is OEI.
If there is no procedural requirement related to obstacles, then my operating rules limit is WAT. If there are procedural limits, then I operate to a mass that allows me to follow my operating techniques and remain above the obstacle clearance plane. That mass needs to calculated by performance folks who take into account where the operating techniques place the aircraft in relation to the obstacles.
Much good work is done every day on operational take-off procedure design.
Operational missed approach procedural design is much more difficult and not as commonly done due to the difficulty of establishing the actual commencement point of the climb and the related issue of keeping the operational missed approach flightpath above the Instrument Procedure obstacle clearance plane.
Stay Alive,