Has anyone built and tested one of these yet?
http://www.patentstorm.us/patents/6133857/description.html Not that I have seen, but then I am not a pilot, simmer or aircraft engineer. I guess that many would say that such a device is an unnecessary expense for what amounts to a double-check. Others might see it as an essential piece of safety equipment.
The key element in this design appears to be the independently derived real-time data, which does not rely 'assumed' values entered before t/o, but calculates them during the roll. As long as the right airport and runway is entered into the FMGC, it should 'work'. For complete confidence, link the system to the auto thrust.