but I mean I find it strange that they haven't also lowered the dry screen height to 15' and just left it at that.
Unfortunately, I don't have the written rationale behind the wet reduction so I can only surmise. My view is that 35 ft is the standard and, for wet, 15 ft should be viewed as a concession.
The USAF, perennially underpowered reduced the screen height, wet or dry, to ZERO
I wasn't aware of that approach ... making TORR super-serious. Given that the performance numbers aren't precise, although reasonably indicative, what sort of percentage of takeoffs at critical weights throw up some dirt and grass off the runway end ?
if missing the hotel by 15' is OK on a rainy day
.. but keep in mind that we are looking at gross and net flight paths. A serious real in-close obstacle is a worry ... one at 5 miles, not so much ...
On some runways it is possible to have a higher weight on a wet runway than dry, but some operators don't allow you to do that:
..along with the regulator .. refer back to the FAA video link earlier
35' is safer than 15', perhaps,
As GF observed earlier, it's just a number, a line in the sand, albeit based on rational historical data risk assessment. What we have up our sleeves is the gross to net margin .. It really doesn't warrant endeavouring to pull out your tape measure and fret over the last millimetre.
The new definition is that its always wet unless its completely dry
While I have no problem with damp being dry, the end result doesn't appear to have a problem either which way. Have I missed something along the way ?
If you took off at TOPL weight AND ..
We need to keep in mind that the OEI figure is but one of a number of cases considered .. the worst of which defines the TO weight
The reduced runway braking action is the only reason we use wet performance, its all about stopping.
Not quite, if you have standing water, increased rolling and impingement drag (ie go considerations) are very relevant