Originally Posted by
172_driver
While I appreciate the airmanship of the story presented by the OP it's not an everyday case with faulty instrument readings. A much more common threat is the faulty inputs of weight in the TODC (Boeing OPT, Airbus FlySmart etc). A system that dynamically calculates the latest stopping point still needs the correct input. Same for an expected acceleration feature.
More mass means less acceleration. If you have a given thrust (from engine setting), mass (from crew input), and acceleration (from IRS) but they don't match, at least one of the three must be wrong and you'd know by like 30 knots. No need to count markers or look at speed readout; the IRS will tell you your longitudinal acceleration is 3.75 meters per second per second.