Climb Limit and Weight Clarification

>I assume the first colume is the>climb limit and the second colume is the runway weight limit.No, the reverse is true. Go to PMDG's wiki-pedia and the assumed temperature takeoff is explained there, with an example. I put all the tables there.Hi Michael,Thanks for posting these at PMDG Ops, but I have something I want to clarify with you. Are you sure the reverse it true? At the top of these charts, it says C-Limit in the first colume and Weight in the second colume next to it going from left to right. In other words, C Limit is on the left and Weight is on the right in these two columes. I think the C means Climb. I want to clarify this because it doesn't look to be the opposite way to me. Of course, I'm not saying that the very first colume is the Climb limit but the climb limit is next to the Weight colume to the left of it. Just want to be sure we're on the same track here. I could not find anything about if the airplane weighs much less than what the chart shows. So for example, if the weight of the airplane is much less, say 200,000 kilograms or 200000, and this is not shown on the performance chart, do you just use the lowest figures in that chart to calculate the take-off performance and the assumed temperature? The lowest climb limit for runway 27R at London Heathrow is 317500 and the lowest weight limit is 311400. So, if my airplane weighs 200,000 kilograms or 20000, do I use a derate or assumed temperature of 66 degrees? Thanks, Ken.