Do you think it is posssible to air-layer the top off an old spruce tree?

I was thinking of using the "bark flap & bridge" style this spring.

Do you have any (non generalised) suggestions?

You can air-layer it if you want, just with that technique. But remind that it can take a while till it has enough roots!

I only have done air-layering one time, so I've no further suggestions than all the basic-things,

I wish you good luck

(Would you take some pictures of your air-layer? Thanks!)

Its certainly possible (just look at nature; it happens!) but as with all conifers; it takes time!

Good luck John!