PPRuNe Forums - View Single Post - F100 - Overshot Runway at Newman Airport (9/1/2020)
Old 13th Jan 2020, 07:49
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73qanda
 
Join Date: Dec 2014
Location: Nz
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Once the RWY condition goes from Wet to Contaminated (above 3mm of standing water), operations are prohibited.
My opinion is that it is important to be aware of what is good ‘classroom knowledge’ and what is good ‘operational knowledge’. ( and I imagine you are, I’ll just put this out there in case it helps someone or adds value to the conversation).It’s certainly handy to know that above 3mm of standing water is considered contaminated when you’re being tested in the classroom, but it is next to useless on an eight mile final when Tower says “ABC new ATIS Foxtrot issued, only change visibility 2500 meters in rain, wind 270 five knots cleared to land”. The Tower controller doesn’t know if there is more than 3mm of standing water on the runway and neither do RFS or the bird man. So at this point the decision is completely human. No book or computer can tell you ‘land’ or ‘don’t land’ because the inputs to the equation are unknown. If you are 60T onto a 3000m runway you can probably safely decide to continue. If you are 66T onto an 1800m runway the decision is a very important one. How each pilot decides to build in a conservative element is up to them to figure out and apply. Curtain has given his example which I’m sure would work very well for many. My way of deciding is a bit different ( it involves excess landing distance available) but it works for me in the heat of the approach which is what matters to me. If you develop a method that works for you and allows for a conservative decision when you are under pressure then you can refine it over the years. ( I’m going to play with CT’s method as a kind of two-step approach and see how that goes).
Once a RWY has been assessed as Contaminated, then it's game over.
Unless there is snow on the runway, who is going to assess it as contaminated in this part of the world? Like I said before, nobody knows if there is more than 3mm of standing water on the runway and I’ve never heard ATC declare that the runway is now contaminated. You’ll get visibility and precipitation type and if you’re very lucky they’ll tell you that the rain is heavy ( in which case I’d just hold til it went through).
Anyway, I’ve learnt something so thanks for that.
If any Tower controllers read this can they report back observed precipitation rates and corresponding visibility’s? I understand that there will be variables such as humidity etc that will bring varying results but it would still be helpful to get a few examples.
Cheers
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