Originally Posted by
Timmy Tomkins
Some years ago there was a suggestion of a blue light speed. Obvious blue light by the runway, your perf calcs say you should be doing, say 80kts, passing that; if you are not then you need to do something.
Old heavy turboprop with crap performance, we used 30sec to 80 kts as a ball park, just as a check.
A check of computed N1 vs FMC N1 is all you need to avoid this.