Thanks for the replies. Chippybus, yes the trend arrow is the sort of thing I had in mind - but from your description (and others in the EK thread) it seems that the arrow is just longer or shorter: it doesn't indicate the precise acceleration figure, and more importantly doesn't indicate if this figure is less than it should be. So you are still making a rule-of-thumb assessment - which strikes me as odd when the computer has all the data necessary to make an exact, objective assessment at every instant of the takeoff roll.
Number34:
Looking outside seems to have worked for the best part of a 106 years
Well, yes - except for all the times it hasn't. Looking outside and "feel" certainly have their place, but my question is why they aren't combined with objective real-time data that is already collected and available - but for some reason not presented to the crew. It's not as if any additional hardware would be required.
sharpclassic:
Surely this is what our performance figures are for?
If I've understood correctly, the performance figures determine how the aircraft
should perform - what I'm curious about is why there is apparently so little real-time monitoring of how the aircraft
actually is performing in comparison with those expected figures.
On the face of it, it would seem that if the crew had an acceleration indicator that flashed red (or whatever) if acceleration was significantly below that expected for that particular takeoff, they would be able to abort very early - and therefore safely. But perhaps there are other factors that mean this would not be a good idea?
Thanks again for your input.