ICAO doc 8168 vol.2 extract.
BTW what aircraft're you flying, and does the manufacturer provide the MACG limit wt charts or are they developed by your company performance engineers?
Seeing you've raised your level of knowledge (and mine!), here's an extract that may also be of interest.
6.2 CLIMB GRADIENT AND MOC
6.2.1 Initial phase
6.2.1.1 The initial phase begins at the earliest missed approach point (MAPt) and ends at the start of climb point
(SOC). The manoeuvre during this phase requires the concentrated attention of the pilot, especially when establishing
the climb and the changes in configuration, and it is assumed that guidance equipment is not utilized during these
manoeuvres. No turns may be specified during this phase.
6.2.1.2 Climb gradient in the initial phase. In the initial phase the flight track is horizontal.
6.2.1.3 Obstacle clearance in the initial phase. In the initial missed approach area, the minimum obstacle
clearance shall be the same as for the last part of the final approach area except where the extension of the intermediate
missed approach surface backwards towards the missed approach point requires less clearance. (See Figures I-4-6-4
and I-4-6-5.)
6.2.2 Intermediate phase
6.2.2.1 The intermediate phase begins at the SOC. The climb is continued at stabilized speeds up to the first point
where 50 m (164 ft) (Cat H, 40 m (132 ft)) obstacle clearance is obtained and can be maintained. In the construction of
this phase it is assumed that advantage may be taken of available navigation guidance. During the intermediate phase,
the missed approach track may be changed from that of the initial phase by a maximum of 15°.
6.2.2.2 Climb gradient in the intermediate phase. The nominal climb gradient (tan Z) of the missed approach
surface is 2.5 per cent (Cat H 4.2 per cent). A gradient of 2 per cent may be used if the necessary survey and
safeguarding can be provided. Additional climb gradients of 3, 4 or 5 per cent may also be specified. These may be
used by aircraft whose climb performance permits the operational advantage of the lower OCA/H associated with these
gradients, with the approval of the competent authority.
Note.— In case of non-precision approach, any intermediate values (e.g. 3.4 per cent) between 2 and 5 per cent
may be considered.
6.2.2.3 Obstacle clearance in the intermediate phase
6.2.2.3.1 In the intermediate missed approach phase, the minimum obstacle clearance shall be 30 m (98 ft) in the
primary area, and in the secondary area the minimum obstacle clearance shall be 30 m (98 ft) at the inner edge,
reducing linearly to zero at the outer edge. See Section 2, Chapter 1, 1.3, “Obstacle clearance”.
6.2.2.3.2 The OCA/H for the nominal 2.5 per cent must always be published on the instrument approach chart. If
additional gradients are specified in the construction of the missed approach procedure, they and their associated
OCA/H values must be published as alternative options.
Note.— MOC may be obtained by increasing the OCA/H or by a longitudinal adjustment of the MAPt or both.
6.2.3 Final phase
The final phase begins at the point where 50 m (164 ft) (Cat H, 40 m (132 ft)) obstacle clearance is first obtained and
can be maintained. It ends at the point at which a new approach, holding or return to en-route flight is initiated. Turns
may be carried out during this phase.
6.2.3.1 Climb gradient in the final phase. The criteria of the intermediate phase apply.
6.2.3.2 Obstacle clearance in the final phase
6.2.3.2.1 In the final missed approach phase of a straight missed approach the minimum obstacle clearance shall
be 50 m (164 ft) (Cat H, 40 m (132 ft)) in the primary area, reducing linearly to zero at the outer edge of the secondary
area. See Figure I-4-6-4.
6.2.3.2.2 Turning missed approaches have specific criteria for MOC and for the arrangement and extent of
secondary areas (see 6.4, “Turning missed approach”).
Note.— MOC may be obtained by increasing the OCA/H or by a longitudinal adjustment of the MAPt or both. In
addition, obstacles may be excluded from consideration by defining a turn.