OK guys sorry for the mess. I've rewritten my query. Hopefully its better this time.
Please refer to the following chart:
A310 Wet Runway Correction Chart
http://64.176.58.144/wetcorrection.jpg
My querry is about the flex temperature correction given in Note (point no 2) at the end of this chart. The note says:
If V1 corresponding to actual takeoff weight is lower than min V1 then keep Min V1 as V1 for takeoff.
Regarding Flex Temperature, point no 2 of the note says:
If Max TOW has a V1 equal to or above Min V1 decrease Flex Temp by 3 deg C per knot difference between both values.
First of all which Max TOW is under discussion?
Structure limited Max TOW, which is 157000
or
Performance regulated Max TOW, which can be above or below 157000
or
Max TOW for a particular takeoff which relates to the lower of structure limited, landing limited and ZFW limited RTOW.
For an example please refer to the following runway analysis chart
http://64.176.58.144/runwaychart.jpg
Lets say the TOW is 136.4t on a runway more than 3000 meters in length.
In calm wind conditions V1 will be 154
After 10 knots of reduction for wet runway it will be 144
Considering it a slats15/flaps15 takeoff, min V1 is 124
Since Corrected V1 is above min V1 there is no issue.
Now assume the TOW is 120.0t on the same runway.
In calm wind conditions V1 will be 131
After 10 knots of reduction for wet runway it will be 121
Considering slats15/flaps15 takeoff, min V1 is 124
Since the corrected V1 is now below min V1,
Our takeoff V1 will be 124 (which is min V1) but we will have to adjust the flex temperature.
Accroding to point no 2 of the note:
"If Max TOW has a V1 equal to or above Min V1 decrease Flex Temp by 3 deg C per knot difference between both values"
If max TOW is 157t then its V1 is 159 for calm wind condition.
Min V1 is 124
Then 159 - 124 = 35
Decreasing Flex Temp by 3 deg per knot difference between these values means:
35 x 3 = 105
Flex at TOW of 120.0t is 65
Thus 65-105 Means No Flex
So why at lower takeoff weights there is no Flex takeoff when runway is wet as compared to heavy weights?
Thankyou for your patience and time.