I will be honest with you, Stewart, I have never had an olive tree and don't know anything about air-layering it. I do air-layer my "mother" fiddle leaf ficus tree three times each year. I air-layered six of her branches and just this afternoon unwrapped those branches. Anyway, this is what air-layering looks like on a fig tree.
The first photo is the (rooted) air-layered area followed by a photograph of the branch.
drdawg (Dr. Kenneth Ramsey)
The reason it's so hard to lose weight when you get up in age is because your body and your fat have become good friends.