This is an old idea - Boeing invented something like this years ago - IE the notion of takeoff perfromance monitor centered around what they called a "Chrondrasic Interval". The thing worked, was a nobel cause & good innovative engineering. I dont know why it never got implemented. I suspect for product liability reasons - IE Modern day aircraft flight deck & air carrier operations are centered around the FAR "The pilot is ultimately responsible for the safety of his aircraft", Now, this FAR basically shifts all the liability onto the pilot when it starts raining aluminum. However, if you have a takeoff performance monitor - then you start to shift the responsibility back onto the aircraft manufacturer, because this critical step of synthesizing dynamic info is done by the aircraft manufacturer & voila ! product liabilityconcerns !. Now, certainly you do not expect an American COmpany to take on additional risk do you ?? This thing will not get implemented in the US - unless, a foreigner makes it happen first . AIRBUS is much closer to this concept than stodgy old Boeing - IE with the full up envelop protection. That being asaid - this is takeoff performance in my humblest of opinions is somewhat irrelevant on modern jetliners - THE DIRTIER SECRET CONCERNING YOUR CONCERN WITH TAKEOFF PERFORMANCE is display data latency delays. IE The through put of dynamic data such as GS & CAS is delayed in modern avionics systems due to the latency getting from the enviromental sensor - through whatever conputer ( airdata, IRS etc ) down the data bus - into the display processor & upload onto the display - therefore, if the data you are relying on to make these natz-ass decisions is "late" - then what does it all mean ? - yes - Im saying your are always going to be at least faster then what your are indicating - by milliseconds - to seconds - depending on the aircraft your are flying. Put that in your fuse box !