SID climb gradient and acceleration
Hello PPRuNe colleagues,
First question on the forum, but maybe one of you more experienced guys could help to end my sleepless nights over this topic.
Lets create following scenario:
MEDIUM JET AIRCRAFT
Airport at 1000ft MSL
NADP2
SID requires a minimum gradient of 6% till 4000ft.
Now, ICAO NADP2 specifies a thrust reduction, acceleration and flap retraction at 800ft - while maintaining a positive rate of climb.
So, Thrust reduction and Acceleration could be 1800ft/1800ft
For the sake of the question lets assume a V2+10kts of: 155kts and a clean speed of 210kts. This will require a V/S of roughly 930ft/min respectively 1260ft/min.
A 6% till 4000ft requirement would thus not be met, as during the acceleration to clean speed the climb rate will be in any case lower than 930ft/min, at least when flying in managed modes. I understand the 6% till 4000ft as a minimum that always needs to be met, so its not an average up to 4000ft.
Whats your approach to manage this the most elegant way?
My idea would be to alter the acceleration height whenever terrain is an issue and a high climb gradient is necessary. In this example for instance i would therefore enter 1800/4000 into the FMC. Or do I have an entirely false understanding of the problem? XD
Cheers