Finding row number from matrix

Okay so I have a large data set, specifically from a weather balloon, which rises in height and then falls. I'm writing a script to use only the riseing data so I want to use the data up to the row that contains the maximum height. I'm trying to use find but am getting no results:

[row] = find(max(data(:,8)))

row =

     1

Where data is the dataset, and the height is contained in column 8. How can I assign the row number to a variable?

Thanks