That is what happens when you have a bunch of clowns running an airline.
On November 12:
A senior AI official said fog is expected in Delhi around December 22. "We hope to get the required approvals by then."
"The DGCA is not satisfied with the documentation submitted for seeking Cat III clearance. The training and ground classes started last month. Only a handful of B-787 pilots will be ready for Cat III," sources said.
Air India Dreamliners can't take wing in fog - Times Of India
Has nothing to do with the aircraft itself. Rather the airline poorly planning CATIII certification of it's pilots.