Contaminated runway Vs clearway

[Chris Scott]

Good!

In the contaminated case, the clearway is of much less actual value than in the dry case – in fact it may not help at all. The runway position at the wet V1 has to be earlier than for the dry V1, to ensure stop-capability despite the reduced stopping performance. So, in the "go" case, you may be able to reach the screen height before the end of the runway, in which case the clearway is merely an unnecessary luxury. AND, if the rules permit screen height to be lowered from the normal 35ft to 15ft for the wet case, that is even more likely to happen. That's why the decrement has to be higher for the clearway case.

I wish we had some real figures to illustrate the argument, though. Such is life...

Chris