Weight decrement for wet/contaminated runway (A320)
 

Hello, everebody. By using FCOM perfomance you can calculate MTOW. You have to use conservative table for this. If you want to know MTOW on wet/contaminated RW you need to substract weight decrement from MTOW that's determined for dry runway.

For example:
TORA = 3000 m.
Clearway = 400 m.
Temperature = 30 degrees C
Barometric altitude 1000 feet
Wind calm, slope 0%
Conf 1

For this conditions:

MTOW for dry RW = 79100 kg
MTOW for wet RW with clearway = 75200 kg
MTOW for wet RW without clearway = 78100 kg

Why MTOW with clear way less then MTOW without clearway??? It should be the opposite, isn't it?

p.s. I'm new here. I've not found the answer in search results.