Changing V1 on contaminated runway
I am a student in a flight school and while reading my book, discussing with my fellow students and reading on the internet (also here) I got a bit confused... here's my question
My book says the following:
In case of poor braking conditions, e.g. a wet runway, it is desirable to reduce the V1 for safety reasons, thus increasing the distance available for abandoning the take-off.
However, in a sample examn question the answers are as follows:
On a dry runway it is recommended to decrease V1 to the lowest value
On a contaminated runway it is recommended to choose the highest value for V1.
(runways are not slippy)
Now to me this seems like a contradiction. If i think about it more here's my conclusions:
On a contaminated runway it would be good to choose a low V1, so you have more stop distance in case of a stop. However the distance to VR is bigger and in case of a go this would cause problems.
If you take a high V1, then you get to VR easily but you have less runway to stop in case you stop.
So which is it? Can someone explain to me what to do, choose the highest or lowest V1 and why?