Estimates for radiative forcing index in aviation


If you want to estimate the impact of your flying, what are the most recent estimates for the radiative forcing index (RFI) of aviation that should be used? It seems like most use IPCC:s number from 1999, which would be appr. 2.7 but with a considerable uncertainty. Other reports seem to be giving estimates between everything from 1 to 6, but most of them are quite old. Are there any newer, reliable studies available that could be useful?

Thanks in advance!