That article in Vertical by KP Sanjeev Kumar (referred to by Vidual), is extremely well written and easy to follow. At the end is contained a pointer to - 'Reject or Continue? Understanding Category A Performance' - another written by KP. There are some small errors in both but he has the ability to capture his reader.
Have you ever pondered over the relevance of the two minimum climb standards - first segment 100ft/min and second segment 150ft/min to the operating environment. Well, very little.
During the provision and amendment of Part 29 (the certification code which contains the provisions for certification in Category A) it was proposed that minimum gradients should be specified. Some parties contended that only a minimum climb standard should be specified (that contained in 29.67) with the gradient data provided as information - specified in 29.1587 as the provision of:
"The steady gradient of climb for each weight, altitude, and temperature for which take-off data are to be scheduled..."
It is this data that relates to the operating environment; it is provided (as in the S92A manual) as graphs showing:
"Mean height gained in 100ft horizontal distance applicable ..."
i.e. to: (1) the specified Vtoss applicable from 35ft - 200ft; or (2) the best rate of climb speed (BROC) applicable from 200ft - 1000ft, (both adjusted for installed equipment - i.e. anti-ice, air conditioner etc.). This is effectively shown as a percentage - i.e. height gained in feet/100.
These gradients can be related to the heliport data - for example the gradient of the take-off 'design slope category A', is 4.5% (also shown as a ratio of 1:22.2) providing an angle of 2.58 degrees.
The pilot is now able to relate the data i.e. rejected take-off distance (to the length of the FATO), take-off distance required (to the length of the FATO plus any clearway), and climb gradient (the gradient of the take-off surface), to heliport information and obstacle data.
Far from the steep slopes that are usually shown in RFM or presentation diagrams (of which I am myself guilty), a 100ft/min climb at a Vtoss of 60kts in ISA conditions provides (only) a gradient of 1.6% or climb angle of about 0.9 degrees.
Not exactly 'Formula 1' stuff is it?