As one who used to operate BAe146-200 in ISA+25 conditions, with nil FMS assistance, clearing altitude restrictions all engines operating was sometimes a challenge!
1. Why bother with ALL requirements?
Pick the most restrictive, eg, the one 'step' that requires the greatest gain in altitude in the shortest distance.
Provided your groundspeed does not vary greatly, if you clear the most restrictive, you are looking good to clear the others. Use the items below to see if/how you will clear the most restrictive.
2. Use Rule of Thumb:
Groundspeed x Gradient = Rate of Climb (or Descent) to make the Gradient.
E.g. 4.0% gradient required to 4200'. V2+10 climb target airspeed = 150kt. 150 x 4.0 = 600. You need to make 600fpm or better at that speed.
Or: 250KIAS climb. 3.3% gradient to FL080. Fudge in some TAS. Try 270 x 3.3 = 890fpm. If you are doing 1000fpm or better, you are laughing like fat spiders.
I don't know too many twin- or three-engined turbojets that couldn't make those gradients with all engines operating.
Don't know the Gradient?
Use ratio that you use for Wx RDR. 1 degree of tilt is approximately 100' at 1nm. Therefore two waypoints that are 12nm apart, the second with an alt requirement 3000' higher is a gradient of how many degrees ....
.... give it a try, you tell me!
3. Use 'the bird' if you have glass.
Note required gradient. In your Vertical Speed/Flight Path Angle window, toggle FPA on climb (without making an FPA selection) whilst doing the climb in another mode. In my aeroplane, the green target comes up on the PFD telling me the gradient it is making right now.
4. Pay attention when you DONT have a requirement.
On a nice day, at or near max TOW, put down your newspaper and note how many miles/DME/GPS/DTR your aeroplane needs to climb 1000' all the way to TOPC.
Put it in your little notebook of factoids that you keep for a rainy day. Pull it out on the rainy day and refer.
e.g. a real stinker, the old BAe 146-200 at ISA+15 all ant-ice off..... 2.5nm per 1000' below FL100 at 250KIAS, 3nm per 1000' at 280KIAS to FL200, 4nm/1000' above FL200.
"I'm doing all that, and it is not making the gradient!"
Consider:
1. Reduce to min clean speed (Vmin+5 or +10)
2. Set MCT (Max continuous thrust).
Much less forward speed with little or nil reduction in RoC = better ANGLE of climb.