PPRuNe Forums - View Single Post - Rejecting A Takeoff After V1…why Does It (still) Happen?
Old 9th Dec 2010, 21:24
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Mad (Flt) Scientist
 
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Correct - only 0.1% of all RTOs resulted in an accident or incident. Sounds very safe to do an RTO.

But

To count all those low speed RTOs to justify your assertion that post-V1 RTOs are not significantly risky is not valid.

The important point is that 2% of RTOs were above 120kts (incidentally, that includes RTOs where V1 was even higher and so it was a pre-V1 RTO). Its stated that "most incidents" occurred for these cases. let's be generous to your case, and say that half of all accidents or incidents were due to that 2%.

RTO below 120kts : 74500 events, 37 accidents or incidents. Event rate, approx 0.05%

RTO above 120kts : 1500 events, 37 adverse outcomes. Event rate : 2%

You are almost 100 times more likely to end up in an accident or incident if you reject above 120kts than if you reject before 120kts. High speed RTOs are demonstrably more hazardous.

Not sure where you get the idea that none of those >120kts RTOs resulted in death or structural damage - "incident" includes "accident" in most cases.

Nothing is certain - no-one is saying (as far as I can see) "post V1 RTOs will kill you ". It all depoends on circumstances. But what is indisputable from the data is that rejections at higher speeds, and especially rejections above V1, significantly increase the risk, and as a result are only justified in truly exceptional circumstances. The default decision, justified by many years of experience, is to GO after V1. It may not be always the perfect decision - but the odds are definitely on your side taking that choice.
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