Originally Posted by Centaurus
Essential Buzz. Your reply quoting a Boeing advice on the matter certainly has got my attention. I suppose you wouldn't have that advice on paper would you? It opens up the subject more than I thought. Please PM me with the info or where I could lay my hands on it. Where there is runway length well in excess of the balanced field length content especially allowing for reduced braking on wet or slippery runways then the abort decision may not be critical, although it may frighten the passengers. I sometimes wonder if pilots are fully aware of how much runway is to spare and keep it up their sleeve for a nasty event.
Logically speaking, using a single V1, or a single other speed decision point, whether V1-15, V1-20, V1-30... means neglecting to take account of how much or how little there is excess runway length to spare. An perhaps not being fully aware of this...
Originally Posted by Centaurus
Simulator instructors occasionally see things that horrify them when it comes to rejected take off actions and I have no doubt in my mind that in the real event the chances are delays will occur due indecision and dare I say momentary shock and incompetency and an over-run occurs.
I think official V1 and BFL numbers are supposed to incorporate pilot reaction time somewhere, setting it as 2 seconds. If you think it is going to be more, like 3 or 4 seconds or whatever, you might try and estimate the results - with accompanying changes to V1, BFL, MTOW...
Originally Posted by Centaurus
Depending on the over-run area characteristics (road, ditch, cliff edge and you name it), someone is going to get hurt.
Something is going to get hurt, someone may get hurt.
Originally Posted by Centaurus
There is no shortage of documentary evidence on this subject going back fifty years in old ICAO Accident Reports.
A high speed rejected take off on minimum runway length is something of a gamble that all actions are faultlessly executed. A decision to continue in the case of a late config warning is also a gamble.
High-speed abort past V1 seems to be a somewhat predictable gamble. There is no chance of the plane coming to stop on the runway to taxi back and try again, but there also is no chance of the plane reaching overrun at a speed greater than whatever speed the plane aborts at. So, the outcome depends on the (known) character of the overrun area and (predictable) speed at reaching the overrun.
Whereas continuing is a much bigger gamble. The plane might take off and climb with no problems if the warning was false alarm. Or the plane might barely pass the screen or obstacles, yet make no contact and suffer no damage, and eventually land unhurt. Or alternatively, the plane might hit something at a great speed, trying desperately to gain speed and climbing capability above V2, or enter stall or spin.
Originally Posted by Centaurus
Historically the former has resulted in more fatalities than the latter. Or so I believe personally, anyway.