NoviceF,until recently the FAA had no info regarding the WET screen(the B777 was the only aircraft to do Demonstrated Wet perf')having said that I believe the latest writeups in their Regs refer to the 15'screen.Remember the FAA,due to lobbying of the ATA re'economic considerations refuse to require 'old' a/c to have the charts in the manual.ATA figured that the poss' required payload penalties would incurr to great a financial penalty.Whereas every non FAA a/c dept from US terminals didn't complain..(on a wet takeoff if the technique of Reverser credit ,a reduced V1,and the 15' screen is utilized-payload penalties can be avoided)..The recent JAR(easa)ruling is that the 15' is at the end of the runway..
If your A/c operates in Europe it should have the wet' info in the AFM(Boeing provide Perf'B'(JAR rules)to their offshore customers)..ergo once one has 3mm of water(shiny)on the surface one should review the WET data..
Can't answer for Ausssie,but as they are years ahead with the conservative perf'(alignement distance etc)I imagine they have adopted the WET rules..
Cheers
The 'cost' of developing the wet charts ,for olde' a/c,was argued between the FAA/Air Trans Assoc.......??
