software
The problem is that certification standards won't allow full integration.
The FMS is driven by a 1970's 8086 processor that CAN'T do single point takeoff calculations.
The class 1,2,3 on board that can are not allowed to push weights and V speeds into the FMS.
Alltogether they are not allowed to talk to and synchronize with the weight and balance system on the ground . So it is the pilot's mark1 mod0 eyeball and brain to make sense of the lot and transpose takeoff data from one to the other.
Its all about safety they say.
But if banks (who are even more paranoid about safety) would think the same about a carbon based lifeform and safety in the loop, there wouldn't be any ATMs. Cash would still be delivered by the postman.
The legislator must perform a 180 and allow the push of data into the FMS and if it is just for a plausibility check.
(Okay pool... I am sure you ll find a reason to have a go at me again. Secretly I believe you are my ex-wife)