Comments like yours really drive me up the wall. Nobody doubts that a plane needs to be at least somewhat balanced to fly. It also needs fuel. It needs some semblance of a maintenance schedule. It needs many things. Everyone with a brain knows all this. So then what means beyond in-group signaling is served by hand wringing over any one of the dozens of critical links in the chain?

The bug you cite, which you would not likely even know about if not for other commenters, was only caught because people asked for an old school manual calculation. Had the software process been more transparent it perhaps could have been caught earlier.

The fact that someone failed to properly implement the calculation in software does not change the efficacy of doing the calculation manually. Furthermore, the fact that there were people capable of eyeballing the accuracy of the software outputs seems to back up my point that there are tons of people capable of doing these calculations kicking around.