hello catch up,
just from memory, a rwy is considered contaminated when more than 25% of its length is covered with:
more than 3mm (1/8 inch) of (standing) water or
slush of 1/8 inch or greater
wet snow of 1/4 inch or greater
dry snow of 1 inch or greater
to cope with these contaminants sop usually command a reduction in v1 & a reduction in max take off weight.
also max contaminant depths are defined equal to or above which take off is prohibited.
minimum equipment list (mel) relief is also more restrictive, eg: antiskid must be operative, all thrust reversers must be functional, no assumed temperature t/off thrust etc.
last remark: difference between wet & contaminated rwy is defined for following reasons: although both conditions increase the stopping distances required, first, wet rwy's are more common than contaminated rwy's & then on contaminated rwy's acceleration capabilities can be severely restricted, remember the infamous airspeed ambassador accident in the 1950ties in munich with the manchester football team aboard( "the matt busby babes"),bobby charlton was a survivor.
the probable cause of this accident was an attemted take off on a snow covered rwy & the aircraft never reaching rotation speed, so the aircraft overran the rwy end & broke up. but then, much if not everything had still to be learned concerning contaminated rwy's.
Last edited by blackmail; 19th Feb 2005 at 19:53.